Question

Bipinnaria is the larva of
A. Pila
B. Lamellidens
C. Sepia
D. Asteroidea

Answer 1

Hint: With the auricularia larva of the Holothurians, the bipinnaria larva bears a similar resemblanceThe body of the bipinnaria larva is externally bilaterally symmetrical, but asymmetry is subsequently assumed by the internal structures.It is a free-swimming larva and as the mouth and blastopore become the anus, the anterior end of the archenteron grows.

Complete Answer:
In the larval development of most starfish, bipinnaria is the first stage and is normally accompanied by brachiolaria.Movement and feeding is done by the cilia bands. Starfish that brood their young usually lack a stage of bipinnaria, with miniature adults forming directly into the eggs.

- The Asteroidea class is characterised by this type of larva.
- It has two pre-oral and post-oral ciliate bands.
- The pre-oral ciliate band encircles the larva's pre-oral lobe.
- It is highly evolved to have the pre-oral lobe.
- The ciliated post-oral band tends to be located longitudinally and forms a full ring between the mouth and anus.
- Over a series of body prolongations, called arms, the pre-oral and post-oral ciliate bands are continued.
- The pre-oral and ventral-median arms develop from the ciliated pre-oral band and the rest of the arms develop from the ciliated post-oral band.
- The arms are supplied with muscles which in essence, are contractile.
- There are missing antero-lateral arms.
- These two ciliated bands are known to have originated from a single ciliated band that is subsequently isolated (as in auricularia).
- The entire body is covered by cilia as it initially emerges, but as it develops, these are reduced to a small band forming a number of loops across the surface of the body. On the body, with the ciliated bands extending through them a pair of small, stubby arms soon develop.

The correct Answer is option(D)Asteroidea.

Note: The cilia also capture suspended food particles and carry them to the mouth, in addition to propelling the larva through the water (more correctly called a stomodeum).Eventually, at the front end of the larva, three extra arms develop; it becomes a brachiolaria at this stage. In some species, the bipinnaria grows directly into an adult, like the common starfish Asterias.