Question

Nauplius larva is characteristic of class?
(a) Insecta
(b) Myriapoda
(c) Crustacea
(d) Arachnida

Answer 1

 
Hint: The name ‘Nauplius’ was given by Otto Friedrich Müller posthumously in the year 1785 for animals which are now known to be larvae of a certain group of animals. It is found in the subphylum of Arthropods which include animals such as lobsters, crabs, prawns, krill, woodlice, etc.

Complete Step by Step Answer:
Crustaceans change through many immature and larval stages from the hatching of their eggs to reaching the adult form and each of the stages is separated by a moulting process.
Nauplius larva is free-swimming, planktonic larvae seen in most of the marine and some freshwater crustaceans. There is no evident segmentation seen in these organisms. There are only three pairs of appendages, two antennae, and the mandibles.
The nauplius stage is characterized by the use of the pairs of appendages on the head i.e. the first and the second antennae for swimming. There is a single median, nauplius eye seen in the front of the head. It is known as the nauplius eye for the reason that the "naupliar eye", and is often not seen in the later stages of development. However, it may be retained into the adult stages in some groups, such as the Notostraca.
So, the correct answer is, “Crustacea”.

Note:
- The crustaceans exhibit many different larval forms, nauplius being one of them.
- Nauplius is the earliest and the most characteristic larval form of the crustaceans.
- It is followed by the zoea larva that swims using the thoracic appendages instead of the antennae as in the nauplius larva.
- This stage is followed by a post-larval stage, which is different for different crustaceans.