Question

Mention the important general characters of Urochordata.

Answer 1

Hint: Urochordata is a subphylum of Chordata which includes the Tunicates and other classes such as Larvacea, Thaliacea etc. First, we will know about Urochordata and discuss the important characteristics of Urochordata.

Complete Answer:
Tunicates or Urochordata are marine filter-feeding animals, found at all latitudes, and living mostly in shallow water. They are also known as “Sea Squirts”. Additionally, the tunicates are the only animals known to produce highly crystalline cellulose. The name “Tunicata” is derived from the tissue called the “Tunic”, which contains the cellulose microfibrils.

The important general characters of Urochordata are following:
1. Urochordata or Tunicates are a diverse group of filter-feeding marine invertebrates. The capture planktonic particles by filtering sea water through their bodies.
2. They have hard and leathery outer covering called a “tunic” which is made of cellulose and serves as a protective exoskeleton.
3. Their shape and size are variable in nature, and they can be colonial or solitary, and benthic, pelagic, sessile.
4. They have a central nervous system in the form of a dorsal tube, a pharynx provided with gill slits, a ventral gland secreting iodo proteins and muscular tail.
5. They are hermaphroditic animals, having both sexual and asexual means facilitates for reproduction.
6. They do not have coelom but their development includes a minute, free swimming tadpole larva with a tail, a notochord in tail and a dorsal nerve cord.
7. Metabolic wastes are excreted from various body parts, including the surfaces of the gills and the intestine.
8. They have an open type of circulatory system.

Note: Urochordates are exclusive to marine environments. Their chordates features can be seen in larval stages containing dorsal nerve chords and notochords. The notochord is present during the larval stage and it disappears during metamorphosis.