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 action ...
. The great majority of ctenostome species are marine, although ''
Paludicella
''Paludicella'' is a genus of freshwater bryozoa
Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic invertebrate animals, nearly all living in sedentary colonies. Typically about ...
'' inhabits freshwater. They are distinguished from their close relatives, the
cheilostomes, by their lack of a calcified exoskeleton. Instead, the exoskeleton is
chitin
Chitin ( C8 H13 O5 N)n ( ) is a long-chain polymer of ''N''-acetylglucosamine, an amide derivative of glucose. Chitin is probably the second most abundant polysaccharide in nature (behind only cellulose); an estimated 1 billion tons of chit ...
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, stolons (from Latin '' stolō'', genitive ''stolōnis'' – "branch"), also known as runners, are horizontal connections between organisms. They may be part of the organism, or of its skeleton; typically, animal stolons are external s ...
s, although more compact forms also exist.
References
Protostome orders
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