The hemichordates are also known as the half notochord organism. They were also considered a part of chordate. They were placed in chordates by Bateson. They are known as independent invertebrate by Hyman, Van der Horst, and Dawydoof. They are mainly marine and occur ...

The antedon is also known as the feather star. It occurs in the bottom half of shallow part of sea. It feeds on plankton and debris and has great power of the regeneration and autotomy. Their body has a disc which is cup shaped. It ...

The holothuria is also known as the sea cucumber. It occurs in the shallow part of sea. It respires through cloacae. It feeds on plankton and debris. It has a couple of respiratory trees which open into rectum. The cloacae contracts which leads to the ...

The ophiothrix is also known as brittle star. It occurs in the shallow part of sea. They kill the animals with the help of their arms. Their target animals are mollusca and crustaceans. Their swimming action resembles that of snake. They do take debris and ...

The asterias is also known as star fish. They are carnivorous and reside in the rocky areas. They have a higher power of regeneration and autotomy. There body is divided into two parts. The upper surface is known as aboral surface while the lower surface ...

The phylum echinodermata is divided into many classes. It includes asteroidea, ophiuroidea, echinoidea, holothuroidea and crinoidea. The asteroidea are also known as the star form organisms. There body is flat and have short spines. Their arms are marked with the absence of pedicellariae. The oral ...

The echinodermata are known as the spiny skinned animal. They bear spines which play an important role in protection. The name echinodermata was introduced by Jacob Klein. Leuchart put these organisms into separate phyla. They arise from the three germ layers such as ectoderm, mesoderm ...

The phylum mollusca are divided into different classes which are known as monoplacophora, amphineura, scaphopoda, gastropoda, pelecypoda and cephalopoda. The monoplacophora are known as single plate bearing animals. Their shell is spoon shape with tentacles on the head. They are the connecting link between phylum ...