Echinoderms characterization

Question

According to illustrations of representing beings, how are echinoderms characterized, fundamental morphology, kind of symmetry, germ layers and coelom, respiratory system, digestive system, excretory system, circulatory system, nervous system and kinds of reproduction?

Answer 1

Illustrations of representing beings: sea urchin, sea cucumber and starfishes. Fundamental morphology: calcareous endoskeleton with spines and ambulacral system. Kind of symmetry: secondary radial. Germ layers and coelom: triploblastics and coelomates. Digestive system: complete and deuterostomes. Respiratory system: non-existent. Circulatory system: non-existent. Excretory system: non-existent. Nervous system: simple, nerve network with no ganglia or cephalization. Kinds of reproduction: sexual with the larval stage.