Polycarpa aurata


DISTRUBITION: Western Pacific

HABITAT: All tunicates are marine. It attaches itself to rocky surfaces or exposed dead coral under ledges between 10-20 meters.  

APPEARANCE: Sessile barrel-shaped with a mature size 5 in.  It is usually bright yellow or yellow-orange, and is smooth and leather-like to the touch. Tunicate bodies are covered by a complex skin, properly called a tunic, which is the source for their name. Most tunicates have two main openings, one to “inhale” water and the other to “exhale”.

DIET:  Filter feeder on plankton and detritis. A single tunicate can filter thousands of gallons a day.

REPRODUCTION AND DEVELOPMENT: Tunicates use broadcast spawning to reproduce sexually, and most are hermaphroditic. They have a seemingly backwards maturation process as one of the few invertebrate chordates. They lose their dorsal nerve and notochord as they become adults, or zooids. Larval and zooid forms are markedly different. Larvae are free-swimming and resemble tad-poles. They have a mouth, called the incurrent siphon and an excurrent siphon and an anus. They possess internal gill structures, a muscular tail, a dorsal nerve, and a notochord. They even have a heart, a stomach, and an eye. Adult tunicates, on the other hand, are mainly sessile (attached) filter feeders. Their bodies, may even house photosynthetic bacteria called Prochloron, which helps to provide nutrition for its host. Mature sea squirts lose much of their vertebrate likenesses, by taking on a barrel-like body shape and eliminating the rudimentary spine and eye. Their siphons become much more pronounced, as does the pharynx (the filtering mechanism/stomach). Adults maintain a small nerve ganglion, grow gonads, and develop a  layer  outer tissue the tunic.

REMARKS: The tunic is strengthened by numerous structural fibers made of a unique compound called tunicin.  P. aurata is known as a “sea squirt” because most will squirt water from their openings if threatened.


WORDPRESS SHORTLINK: http://wp.me/p1DZ4b-aK