Dolioletta is a genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of tunicate

Tunicate

Tunicates, also known as urochordates, are members of the subphylum Tunicata, previously known as Urochordata, a group of underwater saclike filter feeders with incurrent and excurrent siphons that is classified within the phylum Chordata. While most tunicates live on the ocean floor, others such...

s in the family Doliolidae

Doliolidae

Doliolidae is a family of tunicates in the order Doliolida. Members of the family are pelagic and often found far away from coastlines.Members of the family are transparent, gelatinous, barrel-shaped or cylindrical marine organisms. They are mostly small and inconspicuous...

.

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 circular bands of muscle in their body wall sharply.

Biology

They have the complex life cycle typical of the doliolids

Doliolida

Doliolida are small marine animals of the Tunicata phylum, related to salps and pyrosomas. The Doliolid body is small, typically 1–2 cm long, and barrel-shaped; it features two wide siphons, one at the front and the other at the back end, and eight or nine circular muscle strands reminiscent...

, with alternating sexual and asexual phases. They use a net of mucus strands to efficiently trap phytoplankton

Phytoplankton

Phytoplankton are the autotrophic component of the plankton community. The name comes from the Greek words φυτόν , meaning "plant", and πλαγκτός , meaning "wanderer" or "drifter". Most phytoplankton are too small to be individually seen with the unaided eye...

 floating past. They both grow fast and multiply rapidly and a single animal is capable of forming thousands of new individuals in a few days. They sometimes form dense swarm

Swarm

Swarm behaviour, or swarming, is a collective behaviour exhibited by animals of similar size which aggregate together, perhaps milling about the same spot or perhaps moving en masse or migrating in some direction. As a term, swarming is applied particularly to insects, but can also be applied to...

s with up to 500 individuals per square metre.

Species

The World Register of Marine Species lists the following species:

• Dolioletta chuni (Neumann, 1906)
• Dolioletta gegenbauri
  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:...
  
  (Uljanin, 1884)
• Dolioletta mirabilis Korotneff, 1891
• Dolioletta tritonis Herdman, 1888
• Dolioletta valdiviae (Neumann, 1906)