Rectilinear locomotion is used by the giant snakes and almost exclusively by fossorial vertebrates when burrowing.
In those fossorial species that dig burrows as nests but forage above the ground many rodents, such as prairie-dogs, ground squirrels, and groundhogs the digging movements tend to be dorsoventral with alternating limb movement.
Although some fishes and birds dig or bore shallow burrows, they can hardly be considered truly fossorial, as are moles or earthworms.
Locomotion of fossorial amphibians and reptiles tends to be axial; it is appendicular only in mammals.
Although little is known about the habits of the Barbados threadsnake, some scientists hypothesize that its small size combined with its fossorial (burrowing) lifestyle probably compels it to feed on insect larvae, especially those of ants and termites, found in the soil.
All are fossorial (that is, subterranean or burrowing) and are regularly associated with termite and ant nests.
This pattern produces the very jerky and slow forward progression typical of most fossorial locomotion.
Invertebrates crawl either by peristaltic locomotion or by contract anchor extend locomotion, both of which have been described previously (see above Fossorial locomotion).
Although these swimming movements can be considered a form of fossorial locomotion, the following discussion considers only locomotor patterns in which most of the activity of the animals involved is confined to tunnels that they leave behind.
The fossorial vertebrates are found in three classes: amphibians, reptiles, and mammals.
Burrowing (fossorial) snakes are seldom large, and the true burrowers, the Typhlopidae and Leptotyphlopidae, living all their lives like earthworms, are the tiniest snakes of all.
