Velvet worms are ecdysozoan invertebrate animals of the phylum Onychophora (from Greek, onyches, "claws"; and pherein, "to carry") with approximately 200 species, the only phylum within animalia that is wholly endemic to terrestrial environments. These elongate, obscurely segmented organisms have tiny eyes, antennae, many pairs of legs, and slime glands. In appearance they have variously been compared to worms with legs, caterpillars, and slugs. Most common in tropical regions of the Southern Hemisphere, they prey on smaller animals such as insects, which they catch by squirting an adhesive mucus. The two extant families of velvet worms are Peripatidae and Peripatopsidae. They show a peculiar distribution, with the peripatids being predominantly equatorial and tropical, while the peripatop