Question

Aplysia belongs to the group of animals characterised by
1) Pentamerous radial symmetry
2) Body differentiated as head, thorax, abdomen
3) Chitinous exoskeleton
4) Calcareous shell Which one is the correct option,?​

Answer 1

Echinoderms include well known animals, like starfish, sea urchin etc. The larvae of echinoderms have bilateral symmetry but this is lost during metamorphosis, when their bodies are reorganized and develop the characteristic radial symmetry of the echinoderm, typically pentamerism. Hence, option C is correct.

Answer 2

Answer:

Body differentiated as head, thorax, abdomen.

Explanation:

• It has bilateral symmetry.
• The name Aplysia, which derives from the Greek words opisthen for "behind" and branchia for "gills," refers to the position of the Aplysia gill behind the heart.
• Aplysia is a gastropod mollusk belonging to the order Opisthobranchia. Because the sensory tentacles on the top of Aplysia's head, known as rhinophores, resemble rabbit ears slightly, it is frequently referred to as the "sea hare."
• Aplysia does not possess a robust exterior shell like other gastropods do.
• The lack of a strongly calcified shell gives Aplysia a somewhat slug-like appearance; it is a huge (often over 5 kilos), soft-bodied animal with a muscular foot that almost completely covers its underside and crawls along marine bottoms in an inchworm-like manner.

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