family
Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
of
tunicate
A tunicate is a marine invertebrate animal, a member of the subphylum Tunicata (). It is part of the Chordata, a phylum which includes all animals with dorsal nerve cords and notochords (including vertebrates). The subphylum was at one time ca ...
s in the order
Doliolida
The Doliolida are an order of small marine animals of the subphylum Tunicata. They are in the class Thaliacea, which also includes the salps and pyrosomes. The doliolid body is small, typically 1–2 mm long, and barrel-shaped; it featu ...
. Members of the family are
pelagic
The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or wa ...
and often found far away from coastlines.Doliolidae World Register of Marine Species. Retrieved 2011-11-17.
Members of the family are transparent, gelatinous, barrel-shaped or cylindrical marine organisms. They are mostly small and inconspicuous. They have
cilia
The cilium, plural cilia (), is a membrane-bound organelle found on most types of eukaryotic cell, and certain microorganisms known as ciliates. Cilia are absent in bacteria and archaea. The cilium has the shape of a slender threadlike projecti ...
which move water through the
mucus
Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It is ...
nets which they use to trap the
phytoplankton
Phytoplankton () are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater ecosystems. The name comes from the Greek words (), meaning 'plant', and (), meaning 'wanderer' or 'drifter'.
Ph ...
on which they feed. This is in contrast to their close relations, the
salp
A salp (plural salps, also known colloquially as “sea grape”) or salpa (plural salpae or salpas) is a barrel-shaped, planktic tunicate. It moves by contracting, thereby pumping water through its gelatinous body, one of the most efficient ...
s, which use contractions of transverse muscles in the body wall for this purpose. Doliolids also have circular muscles, the sudden contraction of which cause them to move rapidly in a characteristic jerky manner.Pelagic Tunicates JelliesZone. Retrieved 2011-11-17.
They have a complex life cycle, as do other
doliolids
The Doliolida are an order of small marine animals of the subphylum Tunicata. They are in the class Thaliacea, which also includes the salps and pyrosomes. The doliolid body is small, typically 1–2 mm long, and barrel-shaped; it features ...
, with forms that alternate between generations that undergo sexual and
asexual reproduction
Asexual reproduction is a type of reproduction that does not involve the fusion of gametes or change in the number of chromosomes. The offspring that arise by asexual reproduction from either unicellular or multicellular organisms inherit the fu ...
.
Genera
The World Register of Marine Species lists the following genera and species:
*''
Dolioletta
''Dolioletta'' is a genus of tunicates in the family Doliolidae.
Characteristics
Members of the genus ''Dolioletta'' are transparent, gelatinous barrel-shaped animals, usually less than one centimetre long. They move in jerks by contracting the ...
Dolioletta gegenbauri
''Dolioletta gegenbauri'' is a species of tunicate in the family Doliolidae. It is small, exists in various forms and is sometimes found in great abundance in the Atlantic and Pacific waters where it lives.
Life cycle
''Dolioletta gegenbauri'' ...
Doliolum
''Doliolum'' is a genus of tunicates, the members of which move via jet propulsion. A detailed description can be found at .
Species
The World Register of Marine Species lists the following species:Doliolum denticulatum
''Doliolum'' is a genus of tunicates, the members of which move via jet propulsion. A detailed description can be found at .
Species
The World Register of Marine Species lists the following species:Doliolum intermedium
''Doliolum'' is a genus of tunicates, the members of which move via jet propulsion. A detailed description can be found at .
Species
The World Register of Marine Species lists the following species:Doliolum nationalis'' Borgert, 1894