The Greek and Latin words for leg and foot have given English the combining form -pod.
Some words formed with -pod entered English earlier, but a great many were coined in the nineteenth century as the study of entomology and paleontology expanded. Here are a few, with their literal meanings and the date of their earliest citation in the OED.
arthropod 1861 (arthro=joint)
Insects, spiders, and crustaceans are arthropods.
cephalopod 1826 (cephal=head)
Cephalopods are creatures like octopus and squid whose “legs” are attached directly to their heads.
diplopod 1864 (diplo=double)
Diplopods have numerous legs, attached in pairs on each segment of the body. Thousand-leggers (millipedes) are diplopods.
gastropod 1826 (gastro=stomach)
A snail is a gastropod. It moves along with a single muscular “foot” attached to its abdomen.
hexapod 1668 (hex=six)
Insects are hexapods.
isopod 1835 (iso=equal)
An isopod has seven pairs of equal and similarly placed thoracic legs. A familiar isopod is the roly-poly (aka woodlouse/pillbug).
myriapod (myria=10,000) Some of these pod words overlap. A myriapod, like a diplopod, has a lot of legs attached in pairs to the segments of their bodies.
octopod 1817 (octo=eight)
Literally “eight-legged,” an octopod is a cephalopod with eight tentacles.
ornithopod 1886 (ornith=bird)
This name attaches to plant-eating dinosaurs with bird-shaped hips, three- or four-toed feet, powerful teeth and jaws and lack of such features as armor plating.
polypod 1612 (poly=many)
Any animal with several feet is a polypod.
pseudopod 1874 (pseudo=false)
The one-celled amoeba moves by extending bits of its central blob and using them as feet.
pteropod 1833 (ptero=wing)
These are sea mollusks whose “feet” have side projections that look like wings. Some pteropods have the lovely common names of “sea butterflies” and “sea angels.”
sauropod 1884 (sauro=lizard)
Literally “lizard-footed,” the sauropods were the really big dinosaurs, like Brachiosaurus, Diplodocus, and Brontosaurus.
Note: The Diplodocus got its name from a peculiarity of its tail bones. The word combines diplo, “double”+ dokos, “beam.”
theropod 1891 (ther=beast)
Theropods are the carnivorous dinosaurs whose feet resembled those of quadrupeds rather than birds.
Other English words contain the element pod as a prefix or suffix, but this post focuses on animals.