Onychophora

Onychophora, commonly called velvet worms, are a phylum of soft-bodied, legged invertebrates comprising about 180–200 described species. They inhabit moist environments in tropical and subtropical forests, leaf litter, and rotting wood, with a distribution centered in the tropics (Peripatidae) and the southern hemisphere (Peripatopsidae). They are part of Panarthropoda, sharing ancestry with arthropods and tardigrades.

Anatomy: Velvet worms have a long, wormlike body with numerous paired lobopods, typically 13–43 leg pairs, each terminating in a claw. They possess a pair of antennae, simple eyes in some species, a soft cuticle, and a flexible trunk. They have two oral slime glands that eject adhesive slime through oral papillae, which they use to ensnare prey.

Ecology: They are nocturnal predators that feed on small invertebrates; they move slowly and require moist environments to prevent desiccation.

Reproduction: Most species reproduce sexually. Males transfer sperm via a spermatophore that the female takes up; some species lay eggs (oviparous), whereas others give birth to live young (viviparous), sometimes with maternal nourishment.

Classification and evolution: Onychophora comprises two families, Peripatidae (tropics) and Peripatopsidae (southern temperate). The fossil record is sparse, but onychophorans are among the closest living relatives of arthropods and are informative for early panarthropod evolution. Conservation concerns include habitat loss and fragmentation, with many species restricted to small ranges.