Doliolida

Doliolida
Unidentified species of Doliolum about 1.4 mm long
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Subphylum: Tunicata
Class: Thaliacea
Order: Doliolida
Delage & Hérouard, 1898
Suborders
Sexual generation, from the left side: m1-m8: muscle bands; at) atrial apertures; br) branchial apertures; br s) branchial sac; sg) stigmata; st) stomach; ng) nerve ganglion; so) sense organs

The Doliolida are an order of small marine chordates of the subphylum Tunicata. They are in the class Thaliacea, which also includes the salps and pyrosomes.[1][2] The doliolid body is small, typically 1–2 mm 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 of barrel bands.

Like all tunicates, except for the predatory tunicate, they are filter feeders. Unlike the related class Ascidiacea, which are sessile, but like the class Appendicularia, they are free-swimming plankton; cilia pump water through the body which drives them forward. As the water passes through, small particles and plankton on which the animal feeds are strained from the water by the gill slits. Doliolids can also move by contracting the muscular bands around the body creating a temporary water jet that thrusts them forward or backward quite quickly.

The Doliolida have a complicated life cycle that includes sexual and asexual generations. They are nearly exclusively tropical animals, although a few species do occur as far to the north as northern California.

  1. ^ Doliolida World Register of Marine Species. Retrieved 2011-11-17.
  2. ^ Gordon, D.P. (2009). New Zealand inventory of biodiversity: 1. Kingdom Animalia: Radiata, Lophotrochozoa, Deuterostomia. Christchurch: Canterbury University Press. p. 422. ISBN 978-1-877257-72-8.