Question

a note about ascidia.
word limit 150-200

Answer 1

Ascidia is exclusively marine and occurs at all depths of the sea. It is sessile in adult stage, but the larva is a free-swimming form. The adults remain attached to the bottom of the sea or other substrata by its base. Ascidia is a microphagous animal, i.e., it feeds on micro­organisms. The food materials are obtained by ciliary action.

Ascidia, in adult stage, are a fixed form so locomotion in true sense is absent. The move­ment is restricted to the contraction of the body by muscle fibres and the closure of the funnels. But the tadpole larva swims actively in water. The mechanism of swimming in the tadpole is exactly similar to Branchiostoma.


Feeding :

Ascidians are suspension feeders that use a mucous net to filter plankton from the water. Ciliary action moves water into the oral siphon and to the pharynx which resembles a basket. As water is pumped through slits in the pharyngeal basket, out the atrial siphon, it passes through a layer of mucous coating the inside. When the mucous sheet is clogged with food, special structures pass it to a short esophagus and into the stomach.


Reproduction :

This species is hermaphrodite, with a simple reproductive system. Fertilization is external, and after a time in the plankton the free-swimming tadpole larvae will settle and metamorphose.

Answer 2

Hey mate here is your answer

ascidiais a paraphyletic class in the subphylum Tunicata of sac-like marine invertebrate filter feeders.Ascidians are characterized by a tough outer "tunic" made of the polysaccharide cellulose.

habbitat
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Ascidians are found all over the world, usually in shallow water with salinities over 2.5%. While members of the Thaliacea and Larvacea (Appendicularia) swim freely like plankton, sea squirts are sessile animals: they remain firmly attached to their substratum, such as rocks and shells.

There are 2,300 species of ascidians and three main types: solitary ascidians, social ascidians that form clumped communities by attaching at their bases, and compound ascidians that consist of many small individuals (each individual is called a zooid) forming colonies up to several meters in diameter.

Sea squirts feed by taking in water through a tube, the oral siphon. The water enters the mouth and pharynx, flows through mucus-covered gill slits (also called pharyngealstigmata) into a water chamber called the atrium, then exits through the atrial siphon.