PROTOSTOMATA

SYSTEMATIC BIOLOGY					KINGDOM ANIMALIA
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PHYLUM ENTOPROCTA

INTRODUCTION TO THE ENTOPROCTA

Entoprocta (en-to-PROK-ta) is made of two Greek roots that mean anus on the inside [within -endon (ένδον); anus -proktos (πρωκτός)]. The reference is to the placement of the anus within the ring of lophophores.

The entoprocts and ectoprocts (a phylum in the Lophophorata) collectively are known as the bryozoans. These are sessile organisms that usually live in colonies of cup-shaped zoids (Figures A-C) which have ciliated tentacles (lophophores) that function to filter out food particles. The entoprocts have a ring of lophophores that enclose both the mouth and the anus (Figure D). Also, they are blastocoelic. The ectoprocts resemble entoprocts but have their anus external to the lophophore ring and are eucoelomate. Brusca and Brusca (2003) and Nicholas (2001b) consider them to occupy separate phyla, Tudge (2000) and Margulis and Schwartz (1998) do not. Valentine (2004) confirms that they occupy separate major clades of the protostomes and only superficially resemble each other.

*A. Bartensia, a common marine colonial entoproct.*	*B. Urnatella, an entoproct found in freshwater.*	C. An illustration of Pedicellina.	*D. A longitudinal section through the zoid of Pedicellina.* Note the complete digestive tract with the mouth (L) and anus (R), both opening within the tentacular ring.**
Images taken from: A&B: http://animaldiversity.ummz.umich.edu/site/accounts/pictures/Entoprocta.html C&D: http://biodidac.bio.uottawa.ca/thumbnails/catquery.htm?Kingdom=Animalia&phylum=Entoprocta

SYNOPTIC DESCRIPTION OF THE ENTOPROCTA

The following information came from Margulis and Schwartz (1998), Buchsbaum (1938), Barnes (1980), Barnes (1984), Brusca and Brusca (2003), Hickman (1973), Nicholas (2001b), Nielsen (2001), Storer and Usinger (1965), and Tudge (2000).

I. SYNONYMS: bryozoans, entoprocts, kamptozoans, goblet worms.

II. NUMBER: >150 species known.

II. PHYLUM CHARACTERISTICS:

A. Structure

Symmetry: Bilateral

Body Cavity: Pseudocoelom (some claim that it is a true coelom) often occluded by mesenchyme.

Body Covering: Outer cuticle.

Support: Hydrostatic skeleton and cuticle.

Digestive System: Food tube U-shaped. Anus discharges in center of tentacular ring.

Circulatory System: Absent.

Locomotion: Animals sessile; tentacles covered with cilia to move water.

Excretory System: Absent.

Nervous System: Anterior ganglion from which nerves emanate.

Endocrine System: None.

B. Reproduction:

Reproductive System: Most are hermaphroditic, internal fertilization (but no copulation). Budding is common.

Development: Zygote develops by determinate, spiral cleavage into a trochophore-like larva.

C. Ecology: Most are marine (one freshwater form) and sessile as adults. Larvae planktonic.

HIERARCHICAL CLASSIFICATION OF THE ENTOPROCTA

Taxonomy of the phylum follows the system of Brusca and Brusca who recognize a single order with four families. I have assigned the name Entoproctida for its apparent class.

CLASS ENTOPROCTIDA (1 ORDER)

Urnatella, Loxosoma, Loxosomella, Loxokalypus, Myosoma, Pedicellina, Bartensia, Gonypodaria.

This page is maintained by Jack R. Holt. Last modified: 01/05/08.