Species given in the picture belongs to which group of molluscs?
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The Chambered Nautilus is the classic "living fossil" of the class Cephalopoda, preserving the external chambered shell that was common in ancient ammonites.
Step 1: Understanding the Concept:
The Phylum Mollusca is divided into several highly distinct classes based on foot modification, shell structure, and nervous system development. Step 2: Detailed Explanation:
The image displays a living Chambered Nautilus (Nautilus pompilius).
The Nautilus is a famous marine mollusc characterized by a coiled, partitioned, gas-filled pearly shell used for buoyancy control, and a head surrounded by dozens of thin tentacles.
Taxonomically, the Nautilus belongs to the class Cephalopoda (subclass Nautiloidea).
Cephalopods are highly evolved molluscs where the foot is modified into arms/tentacles surrounding a central mouth, and a siphon used for jet propulsion.
While most modern cephalopods (like squids, octopuses, and cuttlefishes) have reduced or lost their shells, the Nautilus is unique as the only living cephalopod with a fully developed external chambered shell.
Gastropods possess a single, typically coiled shell but have a flat creeping foot.
Monoplacophora and Polyplacophora possess cap-like or multi-plated shells and lack the complex head-tentacle arrangement of cephalopods.
Therefore, Nautilus belongs to the Cephalopoda. Step 3: Final Answer:
The species shown in the picture belongs to the Cephalopod group of molluscs.
