GENERAL HISTOLOGY

Detailed explanation-1: -Echinoderms have a delicate epidermis that stretches over an endoskeleton composed of calcium carbonate (calcite) plates called ossicles.

Detailed explanation-2: -The endoskeleton of echinoderms is composed of plates, known as ossicles, that are formed from networks of calcium carbonate crystals called the stereom.

Detailed explanation-3: -The vertebrate endoskeleton is basically made up of two types of tissues (bone and cartilage). During early embryonic development the endoskeleton is composed of notochord and cartilage. The notochord in most vertebrates is replaced by the vertebral column and cartilage is replaced by bone in most adults.

Detailed explanation-4: -Their bodies look like pin cushions. The sea star’s skeleton, like the sea urchin’s, is an endoskeleton consisting of small plates of calcium carbonate embedded in the epidermis. These plates, called ossicles, are much smaller than those of sea urchins.

Detailed explanation-5: -Endoskeleton is an internal skeleton present in the bony or cartilaginous fishes. The cartilaginous fish’s endoskeleton is composed of cartilage. The bony fish’s endoskeleton is mainly of bones. Cartilaginous fish come under the class Chondrichthyes and all bony fish under the class Osteichthyes.