INVERTEBRATE ZOOLOGY - H. I. Shcherbak - 2008

KINGDOM MULTICELLULAR ANIMALS (METAZOA)

SUBKINGDOM TRUE METAZOA (EUMETAZOA)

SECTION TRIPLOBLASTIC (TRIPLOBLASTICA) OR BILATERAL (BILATERIA) ANIMALS

SUBSECTION LOPHOPHORATA (OR TENTACULATA)

PHYLUM PHORONIDA

A small group of marine benthic invertebrates (about 20 described species) with a worm-like body living in tubes. Most phoronids inhabit the bottom of the coastal zone in tropical and temperate regions of all oceans and seas, at depths of up to 50 m. In the Black Sea, one species, Phoronis euxinicola, and the actinotroch larva of another species have been found so far.

Phoronids possess a horseshoe-shaped lophophore. The cutaneous-muscular sac is well developed. The coelom consists of two sections: trunk and lophophoral. The gut is loop-shaped, with the Mouth and anus located close to each other; the anus is positioned outside the tentacle crown. There is a pair of coelomducts opening into the coelom.

The Circulatory system is nearly closed. Respiratory Organs are absent. The Nervous system is represented by a dermal plexus with condensations; special Sense Organs are lacking. Reproduction is both asexual (by transverse fission) and sexual. Phoronids are predominantly hermaphroditic. Development proceeds with metamorphosis.

The phylum Phoronida includes a single Class of the same name.



Last update: 13/08/2026

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