Morchellium argus

Morchellium argus, the red-flake ascidian, is a species of colonial sea squirt, a tunicate in the family Polyclinidae. It is native to shallow water in the northeastern Atlantic Ocean, especially round the coasts of Britain.

Morchellium argus
Morchellium argus, illustrations at top
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Subphylum:
Tunicata
Class:
Ascidiacea
Order:
Aplousobranchia
Family:
Polyclinidae
Genus:
Morchellium
Species:
M. argus
Binomial name
Morchellium argus
Synonyms
  • Amaroucium argus'' Milne-Edwards, 1841
  • Aplidium argus (Milne-Edwards, 1841)

Description

A colony of Morchellium argus consists of a clump of vase-shaped zooids up to 4 cm (1.6 in) long, each supported by a conical stalk about 1 cm (0.4 in) wide, to which sand adheres. Each zooid has a buccal siphon with eight flaps and a tongue-like process underneath. This siphon opens into a large pharynx through which water is drawn into the interior, but the colony has a single exit siphon through which the water from several zooids is expelled. The zooids are translucent white, pale pink or red and there are four small red spots at the entrance to the pharynx, which distinguishes this tunicate from similar species.[2][3]

Distribution and habitat

Morchellium argus is native to the northeastern Atlantic Ocean. It is common round the coasts of Britain, as far north as the Shetland Isles. It is also known from the west of France including Arcachon Bay. It is found at depths down to about 10 m (33 ft) mainly in caves, under overhangs and on vertical surfaces, often among foliose algae.[2][4]

Biology

Morchellium argus draws in water through its buccal siphon, filters out zooplankton and other food particles and then expels the water. Gas exchange takes place at the same time.[2]

Morchellium argus is a hermaphrodite. The gonads are in the body cavity and sperm passes out with the exhalent water. When this sperm is drawn into another individual zooid, internal fertilisation can occur. The early developmental stages take place inside the zooid and the larvae are later liberated into the sea. After a short free-living stage, these attach themselves to a surface, undergo metamorphosis, and start a new colony. Further development is by budding of new zooids. The function of the red spots in the pharynx is unclear.[2]

References
  1. Gittenberger, Arjan (2014). "Morchellium argus (Milne-Edwards, 1841)". WoRMS. World Register of Marine Species. Retrieved 2015-02-04.
  2. Sohier, Sandra; André, Frédéric (2014-10-08). "Morchellium argus (Milne-Edwards, 1841)" (in French). DORIS. Retrieved 2015-02-04.
  3. Hiscock, Keith (2006). "A colonial sea squirt - Morchellium argus: Taxonomy and identification". MarLIN. Retrieved 2015-02-04.
  4. Hiscock, Keith (2006). "A colonial sea squirt - Morchellium argus: General information". MarLIN. Retrieved 2015-02-04.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.