NEET BIOLOGY

Detailed explanation-1: -Starfish, like their close relatives sand dollars and sea lilies, are invertebrates, animals without backbones. It’s no wonder scientists prefer to call them “sea stars."

Detailed explanation-2: -Sea stars, like sea urchins and sand dollars, do not have backbones, which makes them part of a group called invertebrates. Fish have backbones, which makes them vertebrates. Got it? Most sea stars sport spiny skin and five arms, although some can grow as many as 50 arms.

Detailed explanation-3: -sea star, also called starfish, any marine invertebrate of the class Asteroidea (phylum Echinodermata) having rays, or arms, surrounding an indistinct central disk.

Detailed explanation-4: -Sea stars are invertebrates so they don’t have a backbone, but they do have a skeleton beneath their skin. This endoskeleton is made up of a complex network of hard bony plates made of calcium carbonate and held together by strong flexible tissues.

Detailed explanation-5: -Soft-bodied animals called mollusks are the second largest group of invertebrates. Octopuses, jellyfish, sponges, and starfish are a few of the many mollusks that live in or near the water. Some mollusks, such as snails, clams, and oysters, do not have an exoskeleton.