Climate Change Science Program

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Climate_Change_Science_Program 

The Climate Change Science Program (CCSP) was the program responsible for coordinating and integrating research on global warming by U.S. government agencies from February 2002 to June 2009. Toward the end of that period, CCSP issued 21 separate climate assessment reports that addressed climate observations, changes in the atmosphere, expected climate change, impacts and adaptation, and risk management issues. Shortly after President Obama took office, the program's name was changed to U.S. Global Change Research Program (USGCRP) which was also the program's name before 2002. Nevertheless, the Obama Administration generally embraced the CCSP products as sound science providing a basis for climate policy. Because those reports were mostly issued after the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), and in some cases focused specifically on the United States, they were generally viewed within the United States as having an importance and scientific credibility comparable to the IPCC assessments for the first few years of the Obama Administration.

The products

The primary outputs from the CCSP were its strategic plan and 21 Synthesis and Assessment Products (SAP), five of which were released on January 16, 2009, the last business day of the Bush Administration. The CCSP Strategic Plan of 2003 defined five goals:

1. Extend knowledge of the Earth’s past and present climate and environment, including its natural variability, and improve understanding of the causes of observed changes (see Observations and causes of climate change),
2. Improve understanding of the forces bringing about changes in the Earth’s climate and related systems (see Changes in the atmosphere)
3. Reduce uncertainty in projections of how the Earth’s climate and environmental systems may change in the future (see Climate projections)
4. Understand the sensitivity and adaptability of different natural and managed systems to climate and associated global changes (see Impacts and adaptation)
5. Explore the uses and identify the limits of evolving knowledge to manage risks and opportunities related to climate variability and change (see Using information to manage risks)

The plan also proposed 21 SAP's, each of which were designed to support one of these five goals. The plan was updated in 2008. The following sections discuss the SAP's, grouped according to the five topic areas.

Observations and causes of climate change

Three SAP's evaluated observations of climate change and our ability to definitively attribute the causes of these changes.

Temperature trends in the lower atmosphere (SAP 1.1)

NOAA released the first of 21 CCSP Synthesis and Assessment reports in May 2006, entitled Temperature Trends in the Lower Atmosphere: Steps for Understanding and Reconciling Differences. The report identified and corrected errors in satellite temperature measurements and other temperature observations, which increased scientific confidence in the conclusion that lower atmosphere is warming on a global scale: "There is no longer a discrepancy in the rate of global average temperature increase for the surface compared with higher levels in the atmosphere," said the report, "the observed patterns of change over the past 50 years cannot be explained by natural processes alone". The report also said that "all current atmospheric data sets now show global-average warming that is similar to the surface warming. While these data are consistent with the results from climate models at the global scale, discrepancies in the tropics remain to be resolved."

The Arctic and other high latitude areas (SAP 1.2)

On January 16, 2009 (the last business day of the Bush Administration), USGS released Past Climate Variability and Change in the Arctic and at High Latitudes. According to the USGS press release, the report shows that:

• The Arctic has recently been warming about as rapidly as it has ever warned throughout the entire record of past Arctic climate.
• The loss of sea ice during summers over the last few decades is highly unusual compared to the last few thousand years. Changes in Earth's orbit alone would have increased summer sea ice.
• Sustained warming of at least 2 to 7 °C would be likely to eventually melt the entire Greenland ice sheet, which would raise sea level by several meters.
• The past tells us that when thresholds in the climate system are crossed, climate change can be very large and very fast. No one knows whether human activities will trigger such events in the coming decades and centuries.

Attribution of the causes of observed climate change (SAP 1.3)

NOAA released Re-Analyses of Historical Climate Data for Key Atmospheric Features: Implications for attribution of causes of observed change in December 2008. According to the report, from 1951 to 2006 the yearly average temperature for North America increased by 1.6° Fahrenheit, with virtually all of the warmingsince 1970. During this period, the average temperature has warmed approximately 3.6 °F over Alaska, the Yukon Territories, Alberta, and Saskatchewan, but no significant warming occurred in the southern United States or eastern Canada. More than half of the warming of North America is likely (more than 66 percent chance) to have resulted from human activity.

There is less evidence that precipitation is changing. The report found no significant trend in North American precipitation since 1951, although there have been substantial changes from year to year and even decade to decade. Moreover, it is unlikely that a fundamental change has occurred in either how often or where severe droughts have occurred over the continental United States during the past half-century. Nevertheless, drought impacts have likely become more severe in recent decades. It is likely that the impacts have been more severe because the recent droughts have lasted a few years, and because warmer temperatures have created stresses in plants, which make them more vulnerable.

Changes in the atmosphere

Scenarios of greenhouse gas emissions and atmospheric concentrations (SAP 2.1)

The US Department of Energy released the second SAP in July 2007, entitled Scenarios of Greenhouse Gas Emissions and Atmospheric Concentrations and Review of Integrated Scenario Development and Application. This two-volume report explored emission scenarios that could stabilize the net effect of greenhouse gases at four different levels. It also outlined key principles and approaches for developing global change scenarios. The two reports were each written by a subset of the members of the Climate Change Science Program Product Development Advisory Committee, a panel organized under the Federal Advisory Committee Act.

The report's executive summary stated that the emission reductions necessary to stabilize radiative climate forcing would "require a transformation of the global energy system, including reductions in the demand for energy... and changes in the mix of energy technologies and fuels." But the authors found great uncertainty in the price that would be necessary to stabilize climate forcing—as well as the resulting economic cost: " These differences are illustrative of some of the unavoidable uncertainties in long-term scenarios."

Other synthesis and assessment products

In addition to SAP 2.1, CCSP produced three other reports to further the goal of improving quantification of climate forcing:

• NOAA released "North American Carbon Budget and Implications for the Global Carbon Cycle" (SAP 2.2) in November 2007.
• NASA released "Atmospheric Aerosol Properties and Climate Impacts" (SAP 2.3) on January 16, 2009.
• NOAA released "Trends in Emissions of Ozone-Depleting Substances, Ozone Layer Recovery, and Implications for Ultraviolet Radiation Exposure" (SAP 2.4) in November 2008.

Climate projections

As provided in the CCSP strategic plan, four SAP's examined issues under CCSP's Goal 3:

• DOE released "Climate Models: An Assessment of Strengths and Limitations." (SAP 3.1) in July 2008.
• NOAA released "Climate Projections Based on Emissions Scenarios for Long-Lived and Short-Lived Radiatively Active Gases and Aerosols." (SAP 3.2) in September 2008.
• NOAA released "Weather and Climate Extremes in a Changing Climate Regions of Focus: North America, Hawaii, Caribbean, and U.S. Pacific Islands." (SAP 3.3) in June 2008.
• USGS released "Abrupt Climate Change." (SAP 3.4) in December 2008.

Impacts and adaptation

Seven SAP's examined the effects of climate change, impacts on people and natural systems, and opportunities and capacity to adapt. Those assessments provided the backbone to the Congressionally mandated Global Climate Change Impacts in the United States which was released in June 2009.

Coastal sensitivity to sea level rise (SAP 4.1)

The U.S. Environmental Protection Agency released Coastal Sensitivity to Sea-Level Rise: A Focus on the Mid-Atlantic Region (SAP 4.1) on January 16, 2009. According to the report's abstract, rising sea level can inundate low areas and increase flooding, coastal erosion, wetland loss, and saltwater intrusion into estuaries and freshwater aquifers. Much of the United States consists of coastal environments and landforms such as barrier islands and wetlands that will respond to sea-level rise by changing shape, size, or position. The combined effects of sea-level rise and other climate change factors such as storms may cause rapid and irreversible coastal change. Coastal communities and property owners have responded to coastal hazards by erecting shore protection structures, elevating land and buildings, or relocating inland. Accelerated sea-level rise would increase the costs and environmental impacts of these responses.

Preparing for sea-level rise can be justified in many cases, because the cost of preparing now is small compared to the cost of reacting later. Examples include wetland protection, flood insurance, long-lived infrastructure, and coastal land-use planning. Nevertheless, preparing for sea-level rise has been the exception rather than the rule. Most coastal institutions were based on the implicit assumption that sea level and shorelines are stable. Efforts to plan for sea-level rise can be thwarted by several institutional biases, including government policies that encourage coastal development, flood insurance maps that do not consider sea-level rise, federal policies that prefer shoreline armoring over soft shore protection, and lack of plans delineating which areas would be protected or not as sea level rises.

A committee set up under the Federal Advisory Committee Act monitored the progress of SAP 4.1, and questioned several aspects of the final report. The original plan included maps and estimates of wetland loss from a then-ongoing EPA mapping study conducted by James G. Titus, who was also a lead author of SAP 4.1. Early drafts included the maps and results, but the final draft did not. Experts and environmental organizations objected to the deletions. The federal advisory committee also took issue with the maps' removal from SAP 4.1 and recommended that EPA publish the mapping study. EPA later confirmed that EPA management had altered the report and suppressed the mapping study, although it declined to explain why.

Thresholds in ecosystems (SAP 4.2)

USGS released Thresholds of Climate Change in Ecosystems (SAP 4.2) on January 16, 2009.

A key premise of the report was that an ecological threshold is the point at which there is an abrupt change in an ecosystem that produces large, persistent and potentially irreversible changes. The report concluded that slight changes in climate may trigger major abrupt ecosystem responses that are not easily reversible. Some of these responses, including insect outbreaks, wildfire, and forest dieback, may adversely affect people as well as ecosystems and their plants and animals. One of the greatest concerns is that once an ecological threshold is crossed, the ecosystem in question will most likely not return to its previous state. The report also emphasized that human actions may increase an ecosystem's potential for crossing ecological thresholds. For example, additional human use of water in a watershed experiencing drought could trigger basic changes in aquatic life that may not be reversible. Ecosystems that already face stressors other than climate change, will almost certainly reach their threshold for abrupt change sooner.

Effects on agriculture, land resources, water resources, and biodiversity (SAP 4.3)

The United States Department of Agriculture released The Effects of Climate Change on Agriculture, Land Resources, Water Resources, and Biodiversity^[26] (SAP 4.3) in May 2008. The executive summary includes the following findings.

Agriculture

• Life cycle of grain and oilseed crops will likely progress more rapidly; but with rising temperatures and variable rainfall, crops will begin to experience failure, especially if precipitation lessens or becomes more variable.
• Climate change is leading to a northward migration of cropland weeds, and range and pasture plant species, which affects crops, grazing land, and livestock operations.
• Higher temperatures will very likely reduce livestock production during the summer season.

Land resources

• Climate change has likely increased the size and number of forest fires, insect outbreaks and tree mortality in the Interior West (Colorado, the Great Basin), Southwest and Alaska
• In arid lands, changes in temperature and precipitation will very likely decrease the vegetation cover that protects the ground surface from wind and erosion.
• Rising CO₂ will very likely increase photosynthesis for forests, but this increase will likely only enhance wood production in young forests on fertile soils.

Water resources

• Runoff may increase in eastern regions, gradually transitioning to little change in the Missouri and lower Mississippi, to substantial decreases in the interior of the west (Colorado and Great Basin).
• Stream temperatures are likely to increase, which will harm aquatic ecosystems.
• Mountain snowpack is declining and melting earlier in the spring across much of the western United States.

Biodiversity

• The rapid rate of warming in the Arctic is dramatically reducing snow and ice cover that provide denning and forage habitat for polar bears.
• Corals in many tropical regions are experiencing substantial mortality from increasing water temperatures, increasing storm intensity, and a reduction in pH.

Adaptation options for climate-sensitive ecosystems and resources (SAP 4.4)

EPA released Preliminary Review of Adaptation Options for Climate-Sensitive Ecosystems and Resources (SAP 4.3) in May 2008. The study focuses on national parks, national forests, national wildlife refuges, wild and scenic rivers, national estuaries, and marine protected areas, all of which are protected by the federal government. The report analyzed how to meet existing management goals set for each protected area to understand what strategies will increase the resilience of each ecosystem.

EPA concluded that climate change can increase the impact of traditional stressors (such as pollution or habitat destruction) on ecosystems, and that many existing best management practices to reduce these stressors can also be applied to reduce the impacts of climate change. For example, current efforts to reverse habitat destruction by restoring vegetation along streams also increase ecosystem resilience to climate change impacts, such as greater amounts of pollutants and sediments from more intense rainfall. EPA also concluded that the nation's ability to adapt to climate change will depend on a variety of factors including recognizing the barriers to implementing new strategies, expanding collaboration among ecosystem managers, creatively re-examining program goals and authorities, and being flexible in setting priorities and managing for change.

Effects of Climate Change on Energy Production and Use (SAP 4.5)

DOE released Effects of Climate Change on Energy Production and Use in the United States (SAP 4.5) in October 2007. The report concludes that the possible impacts of climate change on energy production are important enough to start considering how to adapt. The report's executive summary summarized the report with three questions and answers:

• How might climate change affect energy consumption in the United States? The research evidence is relatively clear that climate warming will mean reductions in total U.S. heating requirements and increases in total cooling requirements for buildings. These changes will vary by region and by season, but they will affect household and business energy costs and their demands on energy supply institutions. In general, the changes imply increased demands for electricity, which supplies virtually all cooling energy services but only some heating services. Other effects on energy consumption are less clear.
• How might climate change affect energy production and supply in the United States? The research evidence about effects is not as strong as for energy consumption, but climate change could affect energy production and supply (a) if extreme weather events become more intense, (b) where regions dependent on water supplies for hydropower and/or thermal power plant cooling face reductions in water supplies, (c) where temperature increases decrease overall thermoelectric power generation efficiencies, and (d) where changed conditions affect facility siting decisions. Most effects are likely to be modest except for possible regional effects of extreme weather events and water shortages.
• How might climate change have other effects that indirectly shape energy production and consumption in the United States? The research evidence about indirect effects ranges from abundant information about possible effects of climate change policies on energy technology choices to extremely limited information about such issues as effects on energy security. Based on this mixed evidence, it appears that climate change is likely to affect risk management in the investment behavior of some energy institutions, and it is very likely to have some effects on energy technology R&D investments and energy resource and technology choices. In addition, climate change can be expected to affect other countries in ways that in turn affect U.S. energy conditions through their participation in global and hemispheric energy markets, and climate change concerns could interact with some driving forces behind policies focused on U.S. energy security.

Effects on Human Health and Welfare and Human Systems (SAP 4.6)

EPA released Analyses of the Effects of Global Change on Human Health and Welfare and Human Systems. (SAP 4.6) in July 2008. The report was directed by Janet L. Gamble of EPA and written by 28 authors. According to EPA, some of the key conclusions of this report are:

• It is very likely that heat-related illnesses and deaths will increase over coming decades.
• An increase in ozone could cause or exacerbate heart and lung diseases.
• Several food and water-borne diseases are likely to be transmitted among susceptible populations, although climate will seldom be the only factor.
• The very young and old, the poor, those with health problems and disabilities, and certain occupational groups are at greater risk.
• The U.S. is better prepared than most developing countries to respond to public health impacts from climate change.
• The most vulnerable areas in the United States are likely to be in Alaska, coastal and river basins susceptible to flooding, and arid areas where water scarcity is a pressing issue, and areas where economic bases are climate-sensitive.
• Populations are moving toward those areas that are more likely to be vulnerable to the effects of climate change.
• The U.S. has a well-developed public health infrastructure and environmental regulatory program to protect our air and water. If these are maintained, the U.S. can respond to many of the effects of climate change, moderating their impact.

The report was formally reviewed by an independent panel set up in compliance with the Federal Advisory Committee Act. This FACA panel's report gave a generally favorable review while providing many specific areas where improvements were needed. The advisory committee's greatest concern was that the report tried so hard to be evenhanded and not overstate what we know, that it came close to leaving the impression that we know little in cases where a lot is known. EPA revised the report to satisfy those concerns and published a response to each of the comments. While not taking issue with the report's findings, the Government Accountability Project complained that EPA delayed releasing the report three months so that its results could be excluded from a regulatory finding about whether greenhouse gases threaten public health.

Impacts on transport and infrastructure (SAP 4.7)

The United States Department of Transportation released Impacts of Climate Variability and Change on Transportation Systems and Infrastructure—Gulf Coast Study (SAP 4.7) in March 2008. The report was prepared by Michael Savonis of the Federal Highway Administration, Joanne Potter (a consultant to DOT), and Virginia Burkett of USGS.

The premise of SAP 4.7 was that climate is changing. Sea levels in the Gulf of Mexico are likely to rise by two to four feet over the next 50 to 100 years from the combination of climate-induced warming and land subsidence. Tropical storms are anticipated to increase in intensity and the number of heavy precipitation events is expected to increase, raising prospects of flooding and structural damage. And the number of very hot days (i.e., >90 °F) could rise by 50%.

The report concluded that the expected impacts of these climate effects on transportation are striking. A significant portion of the region's road, rail, and port network is at risk of permanent flooding if sea levels rise by four feet. This includes more than 2,400 miles (27%) of the major roads, 9% of the rail lines, and 72% of the ports. More than half (64% of interstates; 57% of arterials) of the area's major highways, almost half of the rail miles, 29 airports, and virtually all of the ports are subject to temporary flooding and damage due to increased storm intensity. The increase in daily high temperatures could increase wear on asphalt and the potential for rail buckling. Construction costs are likely to increase because of restrictions on workers on days above 90 degrees Fahrenheit.

Transportation planners can employ climate data to draw meaningful conclusions about the future. In fact, the Gulf Coast Study recommends that transportation decision makers in the Gulf Coast should begin immediately to assess climate impacts in the development of transportation investment strategies. The study also found, however, that transportation planners need new methodological tools to address the longer time frames, complexities and uncertainties that are inherent in projections of climate phenomena. Such methods are likely to be based on probability and statistics (i.e., risk assessment techniques) as much as on engineering and material science.

Using information to manage risks

Three SAP's were prepared to further CCSP's Goal 5

• NASA released "Uses and Limitations of Observations, Data, Forecasts, and Other Projections in Decision Support for Selected Sectors and Regions." (SAP 5.1) in September 2008.
• NOAA released "Best Practice Approaches for Characterizing, Communicating, and Incorporating Scientific Uncertainty in Decisionmaking." (SAP 5.2) on January 16, 2009.
• NOAA released "Decision Support Experiments and Evaluations using Seasonal to Interannual Forecasts and Observational Data." (SAP 5.3) in November 2008.

Global Climate Change Impacts in the United States

To fulfill a statutory requirement for a national assessment, the CCSP released Scientific Assessment of the Impacts of Global Change in the United States in May 2008. Shortly thereafter, a team of authors synthesized key findings from the SAP's. In June 2009, CCSP changed its name to United States Global Change Research Program and released the unified synthesis report, entitled Global Climate Change Impacts in the United States. The report had ten key findings which became the bedrock of the Obama Administration's view of the impacts of climate change.

1. Global warming is unequivocal and primarily human-induced. Global temperature has increased over the past 50 years. This observed increase is due primarily to human-induced emissions of heat-trapping gases.
2. Climate changes are underway in the United States and are projected to grow. Climate-related changes are already observed in the United States and its coastal waters. These include increases in heavy downpours, rising temperature and sea level, rapidly retreating glaciers, thawing permafrost, lengthening growing seasons, lengthening ice-free seasons in the ocean and on lakes and rivers, earlier snowmelt, and alterations in river flows. These changes are projected to grow.
3. Widespread climate-related impacts are occurring now and are expected to increase. Climate changes are already affecting water, energy, transportation, agriculture, ecosystems, and health. These impacts are different from region to region and will grow under projected climate change.
4. Climate change will stress water resources. Water is an issue in every region, but the nature of the potential impacts varies. Drought, related to reduced precipitation, increased evaporation, and increased water loss from plants, is an important issue in many regions, especially in the West. Floods and water quality problems are likely to be amplified by climate change in most regions. Declines in mountain snowpack are important in the West and Alaska where snowpack provides vital natural water storage.
5. Crop and livestock production will be increasingly challenged. Many crops show positive responses to elevated responses to carbon dioxide. However, increased heat, pests, water stress, diseases, and weather extremes will pose adaptation challenges for crop and livestock production.
6. Coastal areas are at increasing risk from sea-level rise and storm surge. Sea-level rise and storm surge place many U.S. coastal areas at increasing risk of erosion and flooding, especially along the Atlantic and Gulf Coasts, Pacific Islands, and parts of Alaska. Energy and transportation infrastructure and other property in coastal areas are very likely to be adversely affected.
7. Risks to human health will increase. Health impacts of climate change are related to heat stress, waterborne diseases, poor air quality, extreme weather events, and diseases transmitted by insects and rodents. Robust public health infrastructure can reduce the potential for negative impacts.
8. Climate change will interact with many social and environmental stresses. Climate change will combine with pollution, population growth, overuse of resources, urbanization, and other social, economic, and environmental stresses to create larger impacts than from any of these factors alone.
9. Thresholds will be crossed, leading to large changes in climate and ecosystems. There are a variety of thresholds in the climate system and ecosystems. These thresholds determine, for example, the presence of sea ice and permafrost, and the survival of species, from fish to insect pests, with implications for society. With further climate change, the crossing of additional thresholds is expected.
10. Future climate change and its impacts depend on choices made today. The amount and rate of future climate change depend primarily on current and future human-caused emissions of heat-trapping gases and airborne particles. Responses involve reducing emissions to limit future warming, and adapting to the changes that are unavoidable.

The organization

The CCSP was known as US Global Change Research Program until 2002, as authorized by the Global Change Research Act of 1990. The Bush Administration changed its name to Climate Change Science Program as part of its U.S. Climate Change Research Initiative. The Administration envisioned "a nation and the global community empowered with the science-based knowledge to manage the risks and opportunities of change in the climate and related environmental systems." President Bush reestablished priorities for climate change research to focus on scientific information that can be developed within 2 to 5 years to assist evaluation of strategies to address global change risks. One the CCSP's cornerstones was the creation of 21 Synthesis and Assessment Products (SAPs) to provide information to help policymakers and the public make better decisions.

Participants

The following is a list of participating agencies.

• Agency for International Development
• United States Department of Agriculture
• Department of Commerce: National Oceanic and Atmospheric Administration and National Institute of Standards and Technology
• United States Department of Defense
• United States Department of Energy
• Department of Health and Human Services, National Institutes of Health
• United States Department of State
• Dept. of Transportation
• United States Department of the Interior, U.S. Geological Survey
• U.S. Environmental Protection Agency
• National Aeronautics & Space Administration
• National Science Foundation
• Smithsonian Institution

The CCSP was guided by a committee of senior representatives from each of these departments and agencies, known as the CCSP Principals. The CCSP was also overseen by the Interagency Working Group on Climate Change Science and Technology. (The committee of CCSP Principals was essentially synonymous with the Subcommittee on Global Change Research of the Committee on Environment and Natural Resources under the National Science and Technology Council in the White House Office of Science and Technology Policy.) Specific program activities were coordinated through Interagency Working Groups. A coordination office facilitated the activities of the Principals and IWGs. That office as well as the IWG's continued to operate when the CCSP became the USGCRP.

Directors

• James R. Mahoney served as the first director of the CCSP and Assistant Secretary of Commerce for Oceans and Atmosphere from April 2002 to March 2006.
• William J. Brennan became Acting Director of CCSP in June 2006. Brennan remained as the acting director until June 2008 when he was confirmed as Assistant Secretary of Commerce for Oceans and Atmosphere and thereby became the director. (Jane C. Luxton of Virginia had been nominated by President Bush in September 2006 for the position, but her nomination was later withdrawn.)
• Jack A. Kaye became Acting Director of CCSP upon Brennan's retirement from NOAA in January 2009.

Reviews and criticism

The Climate Change Science Program operated during an administration that believed that continued scientific investigation was necessary before policies should be implemented. The CCSP faced the challenge of navigating the narrow path between administration officials who were sceptical of the general scientific consensus about greenhouse gases, and scientific critics who were skeptical about almost everything that the administration did related to climate change. As a result, the CCSP was under more scrutiny than most federal scientific coordination programs.

The National Research Council (NRC) reviewed CCSP several times. The NRC's 2004 review concluded that "the Strategic Plan for the U.S. Climate Change Science Program articulates a guiding vision, is appropriately ambitious, and is broad in scope" and "the CCSP should implement the activities described in the strategic plan with urgency." The NRC also recommended that CCSP should expand its traditional focus on atmospheric sciences to better understand the impacts, adaptation, and the human dimension of climate change. More focus on helping decision makers was necessary, it concluded.

A 2007 NRC review was more critical. "Discovery science and understanding of the climate system are proceeding well, but use of that knowledge to support decision making and to manage risks and opportunities of climate change is proceeding slowly." The NRC was particularly critical of the program's failure to engage stakeholders or advance scientific understanding of the impacts of climate change on human well-being. Looking to the future of the program, a 2008 NRC report put forward a set of research recommendations very similar to that embodied in the CCSP Strategic Plan revision of 2008.

The Climate Change Scientific Program was occasionally criticized for the alleged suppression of scientific information. In March 2005, Rick S. Piltz resigned from CCSP charging political interference with scientific reports: "I believe ...that the administration … has acted to impede forthright communication of the state of climate science and its implications for society." Piltz charged that the Bush Administration had suppressed the previous National Assessment on Climate Change, by systematically deleting references to the report from government scientific documents. Piltz later complained about political tinkering with the timing of SAP 4.6, and suppression of sea level rise mapping studies associated with SAP 4.1.

Animal locomotion

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Animal_locomotion 

A beetle larva performing a rectilinear locomotion.

Animal locomotion, in ethology, is any of a variety of methods that animals use to move from one place to another. Some modes of locomotion are (initially) self-propelled, e.g., running, swimming, jumping, flying, hopping, soaring and gliding. There are also many animal species that depend on their environment for transportation, a type of mobility called passive locomotion, e.g., sailing (some jellyfish), kiting (spiders), rolling (some beetles and spiders) or riding other animals (phoresis).

Animals move for a variety of reasons, such as to find food, a mate, a suitable microhabitat, or to escape predators. For many animals, the ability to move is essential for survival and, as a result, natural selection has shaped the locomotion methods and mechanisms used by moving organisms. For example, migratory animals that travel vast distances (such as the Arctic tern) typically have a locomotion mechanism that costs very little energy per unit distance, whereas non-migratory animals that must frequently move quickly to escape predators are likely to have energetically costly, but very fast, locomotion.

The anatomical structures that animals use for movement, including cilia, legs, wings, arms, fins, or tails are sometimes referred to as locomotory organs or locomotory structures.

Etymology

The term "locomotion" is formed in English from Latin loco "from a place" (ablative of locus "place") + motio "motion, a moving".

Locomotion in different media

Animals move through, or on, four types of environment: aquatic (in or on water), terrestrial (on ground or other surface, including arboreal, or tree-dwelling), fossorial (underground), and aerial (in the air). Many animals—for example semi-aquatic animals, and diving birds—regularly move through more than one type of medium. In some cases, the surface they move on facilitates their method of locomotion.

Aquatic

Main article: Aquatic locomotion

Swimming

Dolphins surfing

 

Further information: Fish locomotion

In water, staying afloat is possible using buoyancy. If an animal's body is less dense than water, it can stay afloat. This requires little energy to maintain a vertical position, but requires more energy for locomotion in the horizontal plane compared to less buoyant animals. The drag encountered in water is much greater than in air. Morphology is therefore important for efficient locomotion, which is in most cases essential for basic functions such as catching prey. A fusiform, torpedo-like body form is seen in many aquatic animals, though the mechanisms they use for locomotion are diverse.

The primary means by which fish generate thrust is by oscillating the body from side-to-side, the resulting wave motion ending at a large tail fin. Finer control, such as for slow movements, is often achieved with thrust from pectoral fins (or front limbs in marine mammals). Some fish, e.g. the spotted ratfish (Hydrolagus colliei) and batiform fish (electric rays, sawfishes, guitarfishes, skates and stingrays) use their pectoral fins as the primary means of locomotion, sometimes termed labriform swimming. Marine mammals oscillate their body in an up-and-down (dorso-ventral) direction. Other animals, e.g. penguins, diving ducks, move underwater in a manner which has been termed "aquatic flying". Some fish propel themselves without a wave motion of the body, as in the slow-moving seahorses and Gymnotus.

Other animals, such as cephalopods, use jet propulsion to travel fast, taking in water then squirting it back out in an explosive burst. Other swimming animals may rely predominantly on their limbs, much as humans do when swimming. Though life on land originated from the seas, terrestrial animals have returned to an aquatic lifestyle on several occasions, such as the fully aquatic cetaceans, now very distinct from their terrestrial ancestors.

Dolphins sometimes ride on the bow waves created by boats or surf on naturally breaking waves.

Benthic

Scallop in jumping motion; these bivalves can also swim.

Benthic locomotion is movement by animals that live on, in, or near the bottom of aquatic environments. In the sea, many animals walk over the seabed. Echinoderms primarily use their tube feet to move about. The tube feet typically have a tip shaped like a suction pad that can create a vacuum through contraction of muscles. This, along with some stickiness from the secretion of mucus, provides adhesion. Waves of tube feet contractions and relaxations move along the adherent surface and the animal moves slowly along. Some sea urchins also use their spines for benthic locomotion.

Crabs typically walk sideways (a behaviour that gives us the word crabwise). This is because of the articulation of the legs, which makes a sidelong gait more efficient. However, some crabs walk forwards or backwards, including raninids, Libinia emarginata and Mictyris platycheles. Some crabs, notably the Portunidae and Matutidae, are also capable of swimming, the Portunidae especially so as their last pair of walking legs are flattened into swimming paddles.

A stomatopod, Nannosquilla decemspinosa, can escape by rolling itself into a self-propelled wheel and somersault backwards at a speed of 72 rpm. They can travel more than 2 m using this unusual method of locomotion.

Aquatic surface

Velella moves by sailing.

 

Main article: Animal locomotion on the water surface

Velella, the by-the-wind sailor, is a cnidarian with no means of propulsion other than sailing. A small rigid sail projects into the air and catches the wind. Velella sails always align along the direction of the wind where the sail may act as an aerofoil, so that the animals tend to sail downwind at a small angle to the wind.

While larger animals such as ducks can move on water by floating, some small animals move across it without breaking through the surface. This surface locomotion takes advantage of the surface tension of water. Animals that move in such a way include the water strider. Water striders have legs that are hydrophobic, preventing them from interfering with the structure of water. Another form of locomotion (in which the surface layer is broken) is used by the basilisk lizard.

Aerial

See also: Aeroplankton

Active flight

A pair of brimstone butterflies in flight. The female, above, is in fast forward flight with a small angle of attack; the male, below, is twisting his wings sharply upward to gain lift and fly up towards the female.

 

Main articles: Flight and Flying and gliding animals

Gravity is the primary obstacle to flight. Because it is impossible for any organism to have a density as low as that of air, flying animals must generate enough lift to ascend and remain airborne. One way to achieve this is with wings, which when moved through the air generate an upward lift force on the animal's body. Flying animals must be very light to achieve flight, the largest living flying animals being birds of around 20 kilograms. Other structural adaptations of flying animals include reduced and redistributed body weight, fusiform shape and powerful flight muscles; there may also be physiological adaptations. Active flight has independently evolved at least four times, in the insects, pterosaurs, birds, and bats. Insects were the first taxon to evolve flight, approximately 400 million years ago (mya), followed by pterosaurs approximately 220 mya, birds approximately 160 mya, then bats about 60 mya.

Gliding

Main article: Flying and gliding animals

Rather than active flight, some (semi-) arboreal animals reduce their rate of falling by gliding. Gliding is heavier-than-air flight without the use of thrust; the term "volplaning" also refers to this mode of flight in animals. Thelphis mode of flight involves flying a greater distance horizontally than vertically and therefore can be distinguished from a simple descent like a parachute. Gliding has evolved on more occasions than active flight. There are examples of gliding animals in several major taxonomic classes such as the invertebrates (e.g., gliding ants), reptiles (e.g., banded flying snake), amphibians (e.g., flying frog), mammals (e.g., sugar glider, squirrel glider).

Flying fish taking off

Some aquatic animals also regularly use gliding, for example, flying fish, octopus and squid. The flights of flying fish are typically around 50 meters (160 ft), though they can use updrafts at the leading edge of waves to cover distances of up to 400 m (1,300 ft). To glide upward out of the water, a flying fish moves its tail up to 70 times per second. Several oceanic squid, such as the Pacific flying squid, leap out of the water to escape predators, an adaptation similar to that of flying fish. Smaller squids fly in shoals, and have been observed to cover distances as long as 50 m. Small fins towards the back of the mantle help stabilize the motion of flight. They exit the water by expelling water out of their funnel, indeed some squid have been observed to continue jetting water while airborne providing thrust even after leaving the water. This may make flying squid the only animals with jet-propelled aerial locomotion. The neon flying squid has been observed to glide for distances over 30 m, at speeds of up to 11.2 m/s.

Soaring

Soaring birds can maintain flight without wing flapping, using rising air currents. Many gliding birds are able to "lock" their extended wings by means of a specialized tendon. Soaring birds may alternate glides with periods of soaring in rising air. Five principal types of lift are used: thermals, ridge lift, lee waves, convergences and dynamic soaring.

Examples of soaring flight by birds are the use of:

• Thermals and convergences by raptors such as vultures
• Ridge lift by gulls near cliffs
• Wave lift by migrating birds
• Dynamic effects near the surface of the sea by albatrosses

Ballooning

Ballooning is a method of locomotion used by spiders. Certain silk-producing arthropods, mostly small or young spiders, secrete a special light-weight gossamer silk for ballooning, sometimes traveling great distances at high altitude.

Terrestrial

Main article: Terrestrial locomotion

See also: Comparative foot morphology

 

Forms of locomotion on land include walking, running, hopping or jumping, dragging and crawling or slithering. Here friction and buoyancy are no longer an issue, but a strong skeletal and muscular framework are required in most terrestrial animals for structural support. Each step also requires much energy to overcome inertia, and animals can store elastic potential energy in their tendons to help overcome this. Balance is also required for movement on land. Human infants learn to crawl first before they are able to stand on two feet, which requires good coordination as well as physical development. Humans are bipedal animals, standing on two feet and keeping one on the ground at all times while walking. When running, only one foot is on the ground at any one time at most, and both leave the ground briefly. At higher speeds momentum helps keep the body upright, so more energy can be used in movement.

Jumping

Main article: Jumping

 

Gray squirrel (Sciurus carolinensis) in mid-leap

Jumping (saltation) can be distinguished from running, galloping, and other gaits where the entire body is temporarily airborne by the relatively long duration of the aerial phase and high angle of initial launch. Many terrestrial animals use jumping (including hopping or leaping) to escape predators or catch prey—however, relatively few animals use this as a primary mode of locomotion. Those that do include the kangaroo and other macropods, rabbit, hare, jerboa, hopping mouse, and kangaroo rat. Kangaroo rats often leap 2 m and reportedly up to 2.75 m at speeds up to almost 3 m/s (6.7 mph). They can quickly change their direction between jumps. The rapid locomotion of the banner-tailed kangaroo rat may minimize energy cost and predation risk. Its use of a "move-freeze" mode may also make it less conspicuous to nocturnal predators. Frogs are, relative to their size, the best jumpers of all vertebrates. The Australian rocket frog, Litoria nasuta, can leap over 2 metres (6 ft 7 in), more than fifty times its body length.

Leech moving by looping using its front and back suckers

Peristalsis and looping

Other animals move in terrestrial habitats without the aid of legs. Earthworms crawl by a peristalsis, the same rhythmic contractions that propel food through the digestive tract.

Leeches and geometer moth caterpillars move by looping or inching (measuring off a length with each movement), using their paired circular and longitudinal muscles (as for peristalsis) along with the ability to attach to a surface at both anterior and posterior ends. One end is attached and the other end is projected forward peristaltically until it touches down, as far as it can reach; then the first end is released, pulled forward, and reattached; and the cycle repeats. In the case of leeches, attachment is by a sucker at each end of the body.

Sliding

Due to its low coefficient of friction, ice provides the opportunity for other modes of locomotion. Penguins either waddle on their feet or slide on their bellies across the snow, a movement called tobogganing, which conserves energy while moving quickly. Some pinnipeds perform a similar behaviour called sledding.

Climbing

Some animals are specialized for moving on non-horizontal surfaces. One common habitat for such climbing animals is in trees; for example, the gibbon is specialized for arboreal movement, travelling rapidly by brachiation (see below).

Others living on rock faces such as in mountains move on steep or even near-vertical surfaces by careful balancing and leaping. Perhaps the most exceptional are the various types of mountain-dwelling caprids (e.g., Barbary sheep, yak, ibex, rocky mountain goat, etc.), whose adaptations can include a soft rubbery pad between their hooves for grip, hooves with sharp keratin rims for lodging in small footholds, and prominent dew claws. Another case is the snow leopard, which being a predator of such caprids also has spectacular balance and leaping abilities, such as ability to leap up to 17 m (50 ft).

Some light animals are able to climb up smooth sheer surfaces or hang upside down by adhesion using suckers. Many insects can do this, though much larger animals such as geckos can also perform similar feats.

Walking and running

Species have different numbers of legs resulting in large differences in locomotion.

Modern birds, though classified as tetrapods, usually have only two functional legs, which some (e.g., ostrich, emu, kiwi) use as their primary, Bipedal, mode of locomotion. A few modern mammalian species are habitual bipeds, i.e., whose normal method of locomotion is two-legged. These include the macropods, kangaroo rats and mice, springhare, hopping mice, pangolins and homininan apes. Bipedalism is rarely found outside terrestrial animals—though at least two types of octopus walk bipedally on the sea floor using two of their arms, so they can use the remaining arms to camouflage themselves as a mat of algae or floating coconut.

There are no three-legged animals—though some macropods, such as kangaroos, that alternate between resting their weight on their muscular tails and their two hind legs could be looked at as an example of tripedal locomotion in animals.

Animation of a Devonian tetrapod

Many familiar animals are quadrupedal, walking or running on four legs. A few birds use quadrupedal movement in some circumstances. For example, the shoebill sometimes uses its wings to right itself after lunging at prey. The newly hatched hoatzin bird has claws on its thumb and first finger enabling it to dexterously climb tree branches until its wings are strong enough for sustained flight. These claws are gone by the time the bird reaches adulthood.

A relatively few animals use five limbs for locomotion. Prehensile quadrupeds may use their tail to assist in locomotion and when grazing, the kangaroos and other macropods use their tail to propel themselves forward with the four legs used to maintain balance.

Insects generally walk with six legs—though some insects such as nymphalid butterflies do not use the front legs for walking.

Arachnids have eight legs. Most arachnids lack extensor muscles in the distal joints of their appendages. Spiders and whipscorpions extend their limbs hydraulically using the pressure of their hemolymph. Solifuges and some harvestmen extend their knees by the use of highly elastic thickenings in the joint cuticle. Scorpions, pseudoscorpions and some harvestmen have evolved muscles that extend two leg joints (the femur-patella and patella-tibia joints) at once.

The scorpion Hadrurus arizonensis walks by using two groups of legs (left 1, right 2, Left 3, Right 4 and Right 1, Left 2, Right 3, Left 4) in a reciprocating fashion. This alternating tetrapod coordination is used over all walking speeds.

Centipedes and millipedes have many sets of legs that move in metachronal rhythm. Some echinoderms locomote using the many tube feet on the underside of their arms. Although the tube feet resemble suction cups in appearance, the gripping action is a function of adhesive chemicals rather than suction. Other chemicals and relaxation of the ampullae allow for release from the substrate. The tube feet latch on to surfaces and move in a wave, with one arm section attaching to the surface as another releases. Some multi-armed, fast-moving starfish such as the sunflower seastar (Pycnopodia helianthoides) pull themselves along with some of their arms while letting others trail behind. Other starfish turn up the tips of their arms while moving, which exposes the sensory tube feet and eyespot to external stimuli. Most starfish cannot move quickly, a typical speed being that of the leather star (Dermasterias imbricata), which can manage just 15 cm (6 in) in a minute. Some burrowing species from the genera Astropecten and Luidia have points rather than suckers on their long tube feet and are capable of much more rapid motion, "gliding" across the ocean floor. The sand star (Luidia foliolata) can travel at a speed of 2.8 m (9 ft 2 in) per minute. Sunflower starfish are quick, efficient hunters, moving at a speed of 1 m/min (3.3 ft/min) using 15,000 tube feet.

Many animals temporarily change the number of legs they use for locomotion in different circumstances. For example, many quadrupedal animals switch to bipedalism to reach low-level browse on trees. The genus of Basiliscus are arboreal lizards that usually use quadrupedalism in the trees. When frightened, they can drop to water below and run across the surface on their hind limbs at about 1.5 m/s for a distance of approximately 4.5 m (15 ft) before they sink to all fours and swim. They can also sustain themselves on all fours while "water-walking" to increase the distance travelled above the surface by about 1.3  m. When cockroaches run rapidly, they rear up on their two hind legs like bipedal humans; this allows them to run at speeds up to 50 body lengths per second, equivalent to a "couple hundred miles per hour, if you scale up to the size of humans." When grazing, kangaroos use a form of pentapedalism (four legs plus the tail) but switch to hopping (bipedalism) when they wish to move at a greater speed.

Powered cartwheeling

The Moroccan flic-flac spider (Cebrennus rechenbergi) uses a series of rapid, acrobatic flic-flac movements of its legs similar to those used by gymnasts, to actively propel itself off the ground, allowing it to move both down and uphill, even at a 40 percent incline. This behaviour is different than other huntsman spiders, such as Carparachne aureoflava from the Namib Desert, which uses passive cartwheeling as a form of locomotion. The flic-flac spider can reach speeds of up to 2 m/s using forward or back flips to evade threats.

Subterranean

Some animals move through solids such as soil by burrowing using peristalsis, as in earthworms, or other methods. In loose solids such as sand some animals, such as the golden mole, marsupial mole, and the pink fairy armadillo, are able to move more rapidly, "swimming" through the loose substrate. Burrowing animals include moles, ground squirrels, naked mole-rats, tilefish, and mole crickets.

Arboreal locomotion

Main article: arboreal locomotion

 

A brachiating gibbon

Arboreal locomotion is the locomotion of animals in trees. Some animals may only scale trees occasionally, while others are exclusively arboreal. These habitats pose numerous mechanical challenges to animals moving through them, leading to a variety of anatomical, behavioural and ecological consequences as well as variations throughout different species. Furthermore, many of these same principles may be applied to climbing without trees, such as on rock piles or mountains. The earliest known tetrapod with specializations that adapted it for climbing trees was Suminia, a synapsid of the late Permian, about 260 million years ago. Some invertebrate animals are exclusively arboreal in habitat, for example, the tree snail.

Brachiation (from brachium, Latin for "arm") is a form of arboreal locomotion in which primates swing from tree limb to tree limb using only their arms. During brachiation, the body is alternately supported under each forelimb. This is the primary means of locomotion for the small gibbons and siamangs of southeast Asia. Some New World monkeys such as spider monkeys and muriquis are "semibrachiators" and move through the trees with a combination of leaping and brachiation. Some New World species also practice suspensory behaviors by using their prehensile tail, which acts as a fifth grasping hand.

Energetics

Animal locomotion requires energy to overcome various forces including friction, drag, inertia and gravity, although the influence of these depends on the circumstances. In terrestrial environments, gravity must be overcome whereas the drag of air has little influence. In aqueous environments, friction (or drag) becomes the major energetic challenge with gravity being less of an influence. Remaining in the aqueous environment, animals with natural buoyancy expend little energy to maintain a vertical position in a water column. Others naturally sink, and must spend energy to remain afloat. Drag is also an energetic influence in flight, and the aerodynamically efficient body shapes of flying birds indicate how they have evolved to cope with this. Limbless organisms moving on land must energetically overcome surface friction, however, they do not usually need to expend significant energy to counteract gravity.

Newton's third law of motion is widely used in the study of animal locomotion: if at rest, to move forwards an animal must push something backwards. Terrestrial animals must push the solid ground, swimming and flying animals must push against a fluid (either water or air). The effect of forces during locomotion on the design of the skeletal system is also important, as is the interaction between locomotion and muscle physiology, in determining how the structures and effectors of locomotion enable or limit animal movement. The energetics of locomotion involves the energy expenditure by animals in moving. Energy consumed in locomotion is not available for other efforts, so animals typically have evolved to use the minimum energy possible during movement. However, in the case of certain behaviors, such as locomotion to escape a predator, performance (such as speed or maneuverability) is more crucial, and such movements may be energetically expensive. Furthermore, animals may use energetically expensive methods of locomotion when environmental conditions (such as being within a burrow) preclude other modes.

The most common metric of energy use during locomotion is the net (also termed "incremental") cost of transport, defined as the amount of energy (e.g., Joules) needed above baseline metabolic rate to move a given distance. For aerobic locomotion, most animals have a nearly constant cost of transport—moving a given distance requires the same caloric expenditure, regardless of speed. This constancy is usually accomplished by changes in gait. The net cost of transport of swimming is lowest, followed by flight, with terrestrial limbed locomotion being the most expensive per unit distance. However, because of the speeds involved, flight requires the most energy per unit time. This does not mean that an animal that normally moves by running would be a more efficient swimmer; however, these comparisons assume an animal is specialized for that form of motion. Another consideration here is body mass—heavier animals, though using more total energy, require less energy per unit mass to move. Physiologists generally measure energy use by the amount of oxygen consumed, or the amount of carbon dioxide produced, in an animal's respiration. In terrestrial animals, the cost of transport is typically measured while they walk or run on a motorized treadmill, either wearing a mask to capture gas exchange or with the entire treadmill enclosed in a metabolic chamber. For small rodents, such as deer mice, the cost of transport has also been measured during voluntary wheel running.

Energetics is important for explaining the evolution of foraging economic decisions in organisms; for example, a study of the African honey bee, A. m. scutellata, has shown that honey bees may trade the high sucrose content of viscous nectar off for the energetic benefits of warmer, less concentrated nectar, which also reduces their consumption and flight time.

Passive locomotion

Passive locomotion in animals is a type of mobility in which the animal depends on their environment for transportation; such animals are vagile but not motile.

Hydrozoans

Physalia physalis

The Portuguese man o' war (Physalia physalis) lives at the surface of the ocean. The gas-filled bladder, or pneumatophore (sometimes called a "sail"), remains at the surface, while the remainder is submerged. Because the Portuguese man o' war has no means of propulsion, it is moved by a combination of winds, currents, and tides. The sail is equipped with a siphon. In the event of a surface attack, the sail can be deflated, allowing the organism to briefly submerge.

Mollusca

The violet sea-snail (Janthina janthina) uses a buoyant foam raft stabilized by amphiphilic mucins to float at the sea surface.

Arachnids

The wheel spider (Carparachne aureoflava) is a huntsman spider approximately 20 mm in size and native to the Namib Desert of Southern Africa. The spider escapes parasitic pompilid wasps by flipping onto its side and cartwheeling down sand dunes at speeds of up to 44 turns per second. If the spider is on a sloped dune, its rolling speed may be 1 metre per second.

A spider (usually limited to individuals of a small species), or spiderling after hatching, climbs as high as it can, stands on raised legs with its abdomen pointed upwards ("tiptoeing"), and then releases several silk threads from its spinnerets into the air. These form a triangle-shaped parachute that carries the spider on updrafts of winds, where even the slightest breeze transports it. The Earth's static electric field may also provide lift in windless conditions.

Insects

The larva of Cicindela dorsalis, the eastern beach tiger beetle, is notable for its ability to leap into the air, loop its body into a rotating wheel and roll along the sand at a high speed using wind to propel itself. If the wind is strong enough, the larva can cover up to 60 metres (200 ft) in this manner. This remarkable ability may have evolved to help the larva escape predators such as the thynnid wasp Methocha.

Members of the largest subfamily of cuckoo wasps, Chrysidinae, are generally kleptoparasites, laying their eggs in host nests, where their larvae consume the host egg or larva while it is still young. Chrysidines are distinguished from the members of other subfamilies in that most have flattened or concave lower abdomens and can curl into a defensive ball when attacked by a potential host, a process known as conglobation. Protected by hard chitin in this position, they are expelled from the nest without injury and can search for a less hostile host.

Fleas can jump vertically up to 18 cm and horizontally up to 33 cm; however, although this form of locomotion is initiated by the flea, it has little control of the jump—they always jump in the same direction, with very little variation in the trajectory between individual jumps.

Crustaceans

Although stomatopods typically display the standard locomotion types as seen in true shrimp and lobsters, one species, Nannosquilla decemspinosa, has been observed flipping itself into a crude wheel. The species lives in shallow, sandy areas. At low tides, N. decemspinosa is often stranded by its short rear legs, which are sufficient for locomotion when the body is supported by water, but not on dry land. The mantis shrimp then performs a forward flip in an attempt to roll towards the next tide pool. N. decemspinosa has been observed to roll repeatedly for 2 m (6.6 ft), but they typically travel less than 1 m (3.3 ft). Again, the animal initiates the movement but has little control during its locomotion.

Animal transport

Main article: Phoresis

Some animals change location because they are attached to, or reside on, another animal or moving structure. This is arguably more accurately termed "animal transport".

Remoras

Some remoras, such as this Echeneis naucrates, may attach themselves to scuba divers.

Remoras are a family (Echeneidae) of ray-finned fish. They grow to 30–90 cm (0.98–2.95 ft) long, and their distinctive first dorsal fins take the form of a modified oval, sucker-like organ with slat-like structures that open and close to create suction and take a firm hold against the skin of larger marine animals. By sliding backward, the remora can increase the suction, or it can release itself by swimming forward. Remoras sometimes attach to small boats. They swim well on their own, with a sinuous, or curved, motion. When the remora reaches about 3 cm (1.2 in), the disc is fully formed and the remora can then attach to other animals. The remora's lower jaw projects beyond the upper, and the animal lacks a swim bladder. Some remoras associate primarily with specific host species. They are commonly found attached to sharks, manta rays, whales, turtles, and dugongs. Smaller remoras also fasten onto fish such as tuna and swordfish, and some small remoras travel in the mouths or gills of large manta rays, ocean sunfish, swordfish, and sailfish. The remora benefits by using the host as transport and protection, and also feeds on materials dropped by the host.

Angler fish

In some species of anglerfish, when a male finds a female, he bites into her skin, and releases an enzyme that digests the skin of his mouth and her body, fusing the pair down to the blood-vessel level. The male becomes dependent on the female host for survival by receiving nutrients via their shared circulatory system, and provides sperm to the female in return. After fusing, males increase in volume and become much larger relative to free-living males of the species. They live and remain reproductively functional as long as the female lives, and can take part in multiple spawnings. This extreme sexual dimorphism ensures, when the female is ready to spawn, she has a mate immediately available. Multiple males can be incorporated into a single individual female with up to eight males in some species, though some taxa appear to have a one male per female rule.

Parasites

Many parasites are transported by their hosts. For example, endoparasites such as tapeworms live in the alimentary tracts of other animals, and depend on the host's ability to move to distribute their eggs. Ectoparasites such as fleas can move around on the body of their host, but are transported much longer distances by the host's locomotion. Some ectoparasites such as lice can opportunistically hitch a ride on a fly (phoresis) and attempt to find a new host.

Changes between media

Some animals locomote between different media, e.g., from aquatic to aerial. This often requires different modes of locomotion in the different media and may require a distinct transitional locomotor behaviour.

There are a large number of semi-aquatic animals (animals that spend part of their life cycle in water, or generally have part of their anatomy underwater). These represent the major taxa of mammals (e.g., beaver, otter, polar bear), birds (e.g., penguins, ducks), reptiles (e.g., anaconda, bog turtle, marine iguana) and amphibians (e.g., salamanders, frogs, newts).

Fish

Some fish use multiple modes of locomotion. Walking fish may swim freely or at other times "walk" along the ocean or river floor, but not on land (e.g., the flying gurnard—which does not actually fly—and batfishes of the family Ogcocephalidae). Amphibious fish, are fish that are able to leave water for extended periods of time. These fish use a range of terrestrial locomotory modes, such as lateral undulation, tripod-like walking (using paired fins and tail), and jumping. Many of these locomotory modes incorporate multiple combinations of pectoral, pelvic and tail fin movement. Examples include eels, mudskippers and the walking catfish. Flying fish can make powerful, self-propelled leaps out of water into air, where their long, wing-like fins enable gliding flight for considerable distances above the water's surface. This uncommon ability is a natural defence mechanism to evade predators. The flights of flying fish are typically around 50 m, though they can use updrafts at the leading edge of waves to cover distances of up to 400 m (1,300 ft). They can travel at speeds of more than 70 km/h (43 mph). Maximum altitude is 6 m (20 ft) above the surface of the sea. Some accounts have them landing on ships' decks.

Marine mammals

Pacific white-sided dolphins porpoising

When swimming, several marine mammals such as dolphins, porpoises and pinnipeds, frequently leap above the water surface whilst maintaining horizontal locomotion. This is done for various reasons. When travelling, jumping can save dolphins and porpoises energy as there is less friction while in the air. This type of travel is known as "porpoising". Other reasons for dolphins and porpoises performing porpoising include orientation, social displays, fighting, non-verbal communication, entertainment and attempting to dislodge parasites. In pinnipeds, two types of porpoising have been identified. "High porpoising" is most often near (within 100 m) the shore and is often followed by minor course changes; this may help seals get their bearings on beaching or rafting sites. "Low porpoising" is typically observed relatively far (more than 100 m) from shore and often aborted in favour of anti-predator movements; this may be a way for seals to maximize sub-surface vigilance and thereby reduce their vulnerability to sharks

Some whales raise their (entire) body vertically out of the water in a behaviour known as "breaching".

Birds

Some semi-aquatic birds use terrestrial locomotion, surface swimming, underwater swimming and flying (e.g., ducks, swans). Diving birds also use diving locomotion (e.g., dippers, auks). Some birds (e.g., ratites) have lost the primary locomotion of flight. The largest of these, ostriches, when being pursued by a predator, have been known to reach speeds over 70 km/h (43 mph), and can maintain a steady speed of 50 km/h (31 mph), which makes the ostrich the world's fastest two-legged animal. Ostriches can also locomote by swimming. Penguins either waddle on their feet or slide on their bellies across the snow, a movement called tobogganing, which conserves energy while moving quickly. They also jump with both feet together if they want to move more quickly or cross steep or rocky terrain. To get onto land, penguins sometimes propel themselves upwards at a great speed to leap out the water.

Changes during the life-cycle

An animal's mode of locomotion may change considerably during its life-cycle. Barnacles are exclusively marine and tend to live in shallow and tidal waters. They have two nektonic (active swimming) larval stages, but as adults, they are sessile (non-motile) suspension feeders. Frequently, adults are found attached to moving objects such as whales and ships, and are thereby transported (passive locomotion) around the oceans.

Function

Animals locomote for a variety of reasons, such as to find food, a mate, a suitable microhabitat, or to escape predators.

Food procurement

Animals use locomotion in a wide variety of ways to procure food. Terrestrial methods include ambush predation, social predation and grazing. Aquatic methods include filterfeeding, grazing, ram feeding, suction feeding, protrusion and pivot feeding. Other methods include parasitism and parasitoidism.

Quantifying body and limb movement

Main article: Study of animal locomotion

The study of animal locomotion is a branch of biology that investigates and quantifies how animals move. It is an application of kinematics, used to understand how the movements of animal limbs relate to the motion of the whole animal, for instance when walking or flying.