Question

Under which of the following groups is Neopilina included?
A. Amphineura
B. Monoplacophora
C. Polyplacophora
D. Scaphopoda

Answer 1

Hint: Neopilina is a very primitive mollusk that serves as a type of link between annelids and mollusks. Many fossil relatives of this genus were found in Cambrian to Devonian strata in large numbers. The genus Neopilina was discovered on Mexico's western coast. It is an example of a living fossil. Neopilina is a marine organism feeding on zooplanktons.

Complete answer:
Option: A - Amphineura is a genus of marine mollusks that dates back to the Cambrian epoch. The terminal mouth and anus of the normally extended type preserve bilateral symmetry. Neopilina does not comply with the character of Amphineurans.
Thus, Option A is not correct.
Option: B - Monoplacophora have a bilaterally symmetrical body with a mantle. At the anteromedial and posteromedial ends of the foot, the mouth and anus are located. Neopilina shows characters similar to Monoplacophora and suggested that cephalopods evolved from monoplacophorans.
Thus, Option B is correct.
Option: C - Polyplacophorans, often known as chitons, are bottom-dwelling creatures. They're shaped like a flattened, elongated oval. They can be found on algae and sand, although they prefer firmer surfaces like rocks and corals. All chitons are devoid of a true head, eyes, and tentacles surrounding the mouth. Neopilina does not show characters similar to polyplacophorans.
Thus, Option C is not correct.
Option: D – Neopilina has characters different from that of Scaphopoda.
Thus, Option D is not correct.

Therefore, Option B. Monoplacophora is the correct answer

Note:
Molluscs have a soft, unsegmented body with a muscular foot, a head, a visceral mass holding most of the organ systems, and a fleshy mantle that secretes the calcareous shell. It is the animal kingdom's second biggest phylum. A mantle with a large chamber utilised for breathing and excretion, the existence of a radula (except for bivalves), and the organisation of the nervous system are the three most common traits distinguishing contemporary molluscs.