Seisonidae is a family of
rotifers, found on the gills of ''
Nebalia
''Nebalia'' is a large genus of small crustaceans containing more than half of the species in the order Leptostraca, and was first described by William Elford Leach
William Elford Leach FRS (2 February 1791 – 25 August 1836) was an Engl ...
'', a marine
crustacean
Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group can ...
. Peculiar among rotifers, males and females are both present and equal in size. Males and females are similar with paired
gonads
A gonad, sex gland, or reproductive gland is a mixed gland that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. The male gonad, the testicle, produces sper ...
. It is considered to have diverged from the other rotifers early on, and in one treatment is placed in a separate
class Seisonoidea. They have a large and elongate body with reduced corona.
Their muscular system is similar to that of other rotifers: they have longitudinal muscles as well as open annular muscles.
Species
Two genera with total three species belong to Seisonidae:
[
* '' Paraseison'' Plate, 1887
** '' Paraseison annulatus'' (Claus, 1876) — ectoparasite of ''Nebalia''][
* '' Seison'' Grube, 1861
** '' Seison nebaliae'' Grube, 1861 – ]commensal
Commensalism is a long-term biological interaction (symbiosis) in which members of one species gain benefits while those of the other species neither benefit nor are harmed. This is in contrast with mutualism, in which both organisms benefit fro ...
of ''Nebalia''[
** '' Seison africanus'' Sorensen, Segers & Funch, 2005 — host is unknown.][
]
References
Pararotatoria
Rotifer families
{{Rotifer-stub