Question

Commonest type of larva found in the majority of a crustacean is
A. Tornaria
B. Bipinnaria
C. Nauplius
D. Megalopa

Answer 1

Hint: Crustaceans are a large group of arthropod animals that include prawns, shrimps, crabs, lobsters, etc. They undergo larval stages in the initial developmental period. This larva stage is characterized by three appendages joined to the head. The other characteristic feature is the presence of an unpaired eye.

Step by step answer:Crustaceans form a large group of marine arthropods. Most of the marine animals develop through various differential stages. One of the initial stages that occur after egg ruptures is called the larval stage. The larval stage is of various types differentiated by the shape and size of the body. The larva stage is just the beginning of the life cycle of an organism. The larva undergoes many changes or stages to finally form an adult organism. In crustaceans, two initial stages exist. These are larva sage and immature. The larva stage is represented by Nauplius. It is a very unique and distinct type of larval stage represented by the presence of three main appendages of the head. The larva uses these appendages to swim. Also, the Nauplius larva has unpaired eyes due to its simple organization.
Tornaria is also a larval stage present in Hemichordates like acorn worms. It is a type of planktonic larva. Bipinnaria is a free-living larva belonging to zooplankton. It is characterized by the presence of cilia on all of its body in the initial stages. Megalopa is also a crustacean larva stage. But is rarely found as compared to Nauplius.

Therefore, the correct answer is Nauplius or option C.

Note: The crustaceans undergo different types of larva stage. Each has its own characteristic features. The various larva stage types of crustaceans are Branchiopoda, Cephalocardia, Remipedia, Krill, etc. Each of the developmental stages of crustaceans involves shedding of the hard exoskeleton to grow in size. Thus, crustaceans undergo molting.