Terrestrial locomotion
Videos
Terrestrial locomotion has evolved as animals adapted from aquatic to terrestrial environments. Locomotion on land raises different problems than that in water, with reduced friction being replaced by the increased effects of gravity.
The velvet worm (Onychophora)
A jumping kangaroo.
Helix pomatia crawling over razor blades. Terrestrial gastropods crawl on a layer of mucus. This adhesive locomotion allows them to crawl over sharp objects.
The pangolin Manis temminckii in defensive position.
Amphibious fish
Videos
Amphibious fish are fish that are able to leave water for extended periods of time. About 11 distantly related genera of fish are considered amphibious. This suggests that many fish genera independently evolved amphibious traits, a process known as convergent evolution. These fish use a range of terrestrial locomotory modes, such as lateral undulation, tripod-like walking, and jumping. Many of these locomotory modes incorporate multiple combinations of pectoral-, pelvic-, and tail-fin movement.
Mudskippers (Periophthalmus gracilis shown) are among the most land adapted of fish (excepting, from a cladistic perspective, tetrapods), and are able to spend days moving about out of water.