AP BIOLOGY

Detailed explanation-1: -Echinoderm skeletons are made up of interlocking calcium carbonate plates and spines. This skeleton is enclosed by the epidermis and is thus an endoskeleton.

Detailed explanation-2: -The Phylum Echinodermata doesn’t always have spiny skin, or a spiny surface, but these animals do all share a calcium carbonate internal skeleton, or endoskeleton.

Detailed explanation-3: -Examples of echinoderms include sea stars, sea urchins, sea cucumbers, brittle stars, and feather stars (Fig. 3.83). Although they may appear very different, echinoderms all have two major defining characteristics that set them apart from all other animals: a water vascular system and five-sided radial symmetry.

Detailed explanation-4: -Mammals, reptiles, birds, fish and amphibians are vertebrates with endoskeletons (skeletons inside their bodies). Their skeletons provide support and protection and help them to move. Insects, spiders and shellfish are some of the invertebrates that have exoskeletons.