What are the two main bryozoan forms?
Within the ectoproct bryozoans are two major classes: Phylactolaemata, an exclusively freshwater group, and Gymnolaemata, a vastly larger, polyphyletic collection of species, mostly marine except for a few species in the subclass Ctenostomata that occur in fresh or brackish water.
Are bryozoans harmful to humans?
Each colony, sometimes growing to the size of a soccer ball, is made of many individual creatures called “zooids” which are microscopic creatures with a mouth, digestive tract, muscles, and nerve centers. Freshwater bryozoans are harmless, though they occasionally clog water pipes and sewage treatment equipment.
What animals prey upon bryozoans?
Predators of marine bryozoans include sea slugs (nudibranchs), fish, sea urchins, pycnogonids, crustaceans, mites and starfish. Freshwater bryozoans are preyed on by snails, insects, and fish. In Thailand, many populations of one freshwater species have been wiped out by an introduced species of snail.
What is the anatomy of a bryozoan?
Anatomy & physiology. Bryozoan skeletons grow in a variety of shapes and patterns: mound-shaped, lacy fans, branching twigs, and even corkscrew-shaped. Their skeletons have many tiny openings. Each opening is the home of zooid. They have a body with a U-shaped gut, opening at the mouth and at the anus.
Is a bryozoan a colonial animal?
All bryozoans are colonial except for one genus, Monobryozoon. Individual members of a bryozoan colony are about 0.5 millimetres (0.020 in) long and are known as zooids, since they are not fully independent animals.
Were the first bryozoans soft-bodied or hard-bodied?
It is likely that the first bryozoans appeared much earlier and were entirely soft-bodied, and the Ordovician fossils record the appearance of mineralized skeletons in this phylum.
Are bryozoans unmineralized?
This has led researchers to suspect that bryozoans arose earlier but were initially unmineralized, and may have differed significantly from fossilized and modern forms. Early fossils are mainly of erect forms, but encrusting forms gradually became dominant. It is uncertain whether the phylum is monophyletic.