Question

Trochophore larva is found in
(a)Chiton
(b)Nereis
(c)Aphrodite
(d)All of the above

Answer 1

Hint: The trochophore larva is plankton-like translucent, free-swimming, ciliated structure found in organisms living in marine water bodies, especially in the aquatic worms. It is also known as the Troposphere. The larvae usually survive by feeding on planktonic masses in the sea.

Complete answer:
Trochophore larvae are a characteristic feature of Chiton, Nereis, and Aphrodite.
-The trochophore larvae is a free-swimming larva found in marine mollusks and marine annelids, echiurans, and sipunculans.
-The term ‘trochophore' is derived from the Greek word ‘trokhos’ meaning ‘wheel' and ‘phero' meaning ‘to bear or to carry'.
-The anterior part of their body is broader than the posterior part.
-It possesses bilateral symmetry.
-The body consists of mouth, alimentary canal, and anus. The mouth is located at the midventral line and it opens into the alimentary canal through the stomach. The canal ends at the anus.
-They possess a round wheel-shaped band of cilia that helps in movement and ingestion of food.
-The cilia move rapidly to produce an eddy current which stirs the food close to the larvae.
-They ciliary ring is present both above (prototroch) and below (metatroch) the mouth.
-The development of trochophore larvae into adult organisms follow various stages like early trochophore- complete trochophore- late trochophore- meta trochophore.

So, the correct answer is ‘All of the above'.

Note:
-In some trochophore larvae, an additional ring of cilia can be present which is known as the telotroch.
-Some of the trochophores bear Ocelli or eyespots that help in sensory reception
-Aphrodite is also known as the ‘sea mouse’.
-The larvae was first discovered by the Swedish naturalist Loven in 1840. So, it is sometimes also known as the ‘Loven’s larvae.