The Ctenostomatida are an order of
bryozoans in the class
Gymnolaemata
Gymnolaemata are a class of Bryozoans. Gymnolaemata are sessile, mostly marine organisms and grow on the surfaces of rocks, kelp, and in some cases on animals, like fish. Zooids are cylindrical or flattened. The lophophore is protruded by ac ...
. The great majority of ctenostome species are marine, although ''
Paludicella'' inhabits fresh water. They are distinguished from their close relatives, the
cheilostomes, by their lack of a calcified exoskeleton. Instead, the exoskeleton is
chitin
Chitin (carbon, C8hydrogen, H13oxygen, O5nitrogen, N)n ( ) is a long-chain polymer of N-Acetylglucosamine, ''N''-acetylglucosamine, an amide derivative of glucose. Chitin is the second most abundant polysaccharide in nature (behind only cell ...
ous, gelatinous, or composed only of a soft membrane, and always lacks an
operculum. Colonies of ctenostomes are often composed of elongated, branch-like
stolon
In biology, a stolon ( from Latin ''wikt:stolo, stolō'', genitive ''stolōnis'' – "branch"), also known as a runner, is a horizontal connection between parts of an organism. It may be part of the organism, or of its skeleton. Typically, animal ...
s, although more compact forms also exist.
References
Bryozoan orders
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