INVERTEBRATE ZOOLOGY - H. I. Shcherbak - 2008

KINGDOM MULTICELLULAR ANIMALS (METAZOA)

SUBKINGDOM TRUE METAZOA (EUMETAZOA)

SECTION TRIPLOBLASTIC (TRIPLOBLASTICA) OR BILATERAL (BILATERIA) ANIMALS

SUBSECTION MOLTING ANIMALS (ECDYSOZOA)

PHYLUM CEPHALORHYNCHA

A small group of marine worm-like organisms. Sizes range from 225 µm to 15 cm. About 200 species are known.

The body of cephalorhynchs consists of a proboscis and a trunk. The proboscis comprises an oral cone, a middle region with hooks (scalids), and a neck region. The body is covered with a cuticle. There is a cutaneous-muscular sac. The body cavity is a schizocoel. The gut is complete. The excretory system is protonephridial. The Nervous system consists of a circumoesophageal ring and an unpaired ventral nerve cord. Cephalorhynchs are dioecious. Egg Cleavage is radial and nearly equal. Development proceeds with metamorphosis.

The phylum Cephalorhyncha includes three classes.



Last update: 13/08/2026

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