INVERTEBRATE ZOOLOGY - H. I. Shcherbak - 2008

KINGDOM MULTICELLULAR ANIMALS (METAZOA)

SUBKINGDOM TRUE METAZOANS (EUMETAZOA)

SECTION TRIPLOBLASTIC (TRIPLOBLASTICA) OR BILATERAL (BILATERIA) ANIMALS

SUBSECTION MOLTING ANIMALS (ECDYSOZOA)

PHYLUM VELVET WORMS (ONYCHOPHORA)

Onychophorans are a small group of terrestrial predatory invertebrates that inhabit exclusively humid environments in the tropical and temperate Zones of the Southern Hemisphere. In the Northern Hemisphere, they occur only in Mexico and Southeast Asia. A little over 70 species are currently known.

The body of Onychophora is divided into an indistinctly differentiated HEAD bearing three pairs of appendages and a trunk with paired unsegmented limbs. The body is covered by a thin elastic cuticle, and a well-developed Skin-muscular sac is present. The body cavity is a mixocoel. The Digestive System is poorly differentiated. The Circulatory system is open, and The Heart features metameric ostia. The excretory Organs are numerous metameric

coelomoducts. Onychophorans breathe via tracheae. The Nervous system is ladder-like, lacking distinct ganglia. They are dioecious organisms. Development proceeds without metamorphosis.

The phylum Onychophora includes a single Class.



Last update: 13/08/2026

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