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Animals & Insects
A number of animals have evolved so as to be able to travel over the ground. Terrestrial locomotion has evolved many times as animals moved onto the land from the water. more...
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Types of locomotion
There are three basic forms of locomotion found among terrestrial animals
Legged - Moving by using appendages;
Slithering - moving using the bottom suface of the body;
Rolling - rotating the body over the substrate;
Legged locomotion
Movement on appendages is the most common form of terrestrial locomotion, it is the basic form of locomotion of two major groups with many terrestrial members, the vertebrates and the arthropods. Important aspects of legged locomotion are stance - the way the body is supported by the legs, the number of legs - from two to many, and the foot shape - broad, on toes, etc. There are also many gaits - ways of moving the legs in order to locomote - such as walking, running, or hopping.
Stance
Appendages can be used for movement in a number of ways. The stance, the way the body is supported by the legs, is an important aspect. Charig 1972 identified three main ways in which vertebrates support themselves with their legs - the sprawling stance, the semi-erect stance, and the fully-erect stance. Some animals may use different stances in different circumstances, depending on the stances mechanical and energetic advantages.
The most basic is the sprawling stance. Here the legs are used to drag the body over the land. This is the earliest form of use of legs on land. Amphibious fish such as the mudskipper drag themselves across land on their sturdy fins. Many reptiles and amphibians, some or all of the time, use this method of locomotion. Among invertebrates there is anecdotal evidence that some octopus species (such as the Pinnoctopus genus), sometimes to pursue prey between rockpools, can also drag themselves across land a short distance by hauling its body along by it tentacles, see . There may be video evidence of this .
The second form of stance found among legged terrestrial animals is the semi-erect stance. Here the legs are to the side, but the body is held above the substrate. This mode of locomotion found among some reptiles and amphibians. It is also the main stance of the crocodilians. A few mammals, such as the platypus also use this stance. Among the invertebrates most arthropods, which includes the most diverse group of animals - the insects, have a stance which might best be described as semi-erect.
Finally there is there is the main form of stance of mammal and birds, the fully-erect stance. In these groups the legs are placed beneath the body. This is often linked with the evolution of endothermy (Bakker 1988). The fully-erect stance not-necessarily the 'most-evolved' stance, evidence suggest that crocodilians evolved a semi-erect stance from ancestors with fully-erect stance as a result of adapting to a mostly aquatic lifestyle (Reilly & Elias 1998). For example the mesozoic prehistoric crocodilian Erpetosuchus is believed to have had a fully erect stance and been terrestrial .
Read more at Wikipedia.org
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