The living organism in these animal groups which is entirely aquatic is: C) Echinodermata.
An aquatic animal can be defined as an organism that typically lives and breed inside water bodies such as:
An echinoderm can be defined as any organism that belongs to phylum Echinodermata of aquatic (marine) animals and live entirely there.
Basically, phylum Echinodermata comprises five main classes:
- Echinoidea (sea urchins and sand dollars).
- Holothuroidea (sea cucumbers).
- Ophiuroidea (brittle stars).
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