Entoprocta characteristics

Goblet-shaped and bilaterally symmetrical
A ring of 6 - 36 tentacles around mouth and anus (some authorities say this cannot be described as a lophophore as the tentacles surround the anus, see below)
Tentacles cannot be retracted into body area, but fold over mouth area
Body attached to the substratum by a contractile stalk
U-shaped gut with anus
Colonial and solitary
Sexual and asexual (budding) reproduction possible
Indirect development with planktonic larva
Mainly marine
Layers of muscle
Circulatory or gaseous exchange systems

Greek: entos = inside; proktos = anus

Entoprocts are sometimes called Kamptozoa. They range in height from 0.5 - 5 mm, and 150 species have been described; all are aquatic and mostly marine.

It is thought that they are sequentially hermaphrodite, and that fertilisation may be internal. It is speculated by some authorities that they may be related to the Bryozoans, and that they are not truly pseudocoelomate. Superficially they resemble the hydroid form of Cnidarians.

There are both solitary and colonial species.


Above is Lexosomella sp. a solitary species.

The marine species grow on shells and algae, and are commensal with polychaete annelids. The few freshwater species (see Urnatella gracilis below) are found on the undersides of rocks in running water.

Urnatella gracilis, freshwater entoproct

The body is an oval structure containing the internal organs and an attachment disc or stalk with adhesive glands.

They are filter-feeders with cilia on the tentacles which keep water moving in a steady current, capturing food particles and moving them down to the mouth. The body surface has sensory bristles and pits. Gaseous exchange occurs over the body surface.