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1. Second largest phylum in the animal kingdom
2. Terrestrial or aquatic, triploblastic with organ level organization, bilaterally symmetrical and coelomate animals
3. Body is covered with calcareous shell. Anterior head region has sensory organs called the tentacles
4. The body of the animal is unsegmented with a distinct head, foot and visceral hump
5. A mantle is formed by the soft and spongy layer of the skin over visceral hump. The space between mantle and hump is called as mantle cavity which contains feather-like gills for respiration purposes.
6. The mouth of the animal contains a file-like rasping organ called radula which serves the purpose for feeding.
7. Organisms are dioecious and oviparous. Fertilization is external with indirect development.
8. Organisms belonging to the phylum mollusca – Pila (Apple snail), Pinctada (Pearl oyster), Octopus, squid
A. Pila B. Octopus
1. Marine habitats, triploblastic with organ level organization, coelomate, body shape of adults is radially symmetrical while the larvals are bilaterally symmetrical.
2. Presence of endoskeleton calcareous ossicles, hence the name echinodermata (Echino – spiny bodied)
3. Presence of complete digestive system with mouth and anus
4. Absence of excretory system
5. Characteristic feature of echinoderms is the presence of water vascular system which serves for multiple purposes like locomotion, respiration, capture and transport of food.
6. Animals are dioecious and fertilization is external with indirect development
7. Organisms belonging to phylum Echinodermata – Asterias (Star fish), Echinus (Sea Urchin), Cucumaria (Sea cucumber)
A. Asterias (Star fish)
1. Marine habitat, small-worm like animals, triploblastic with organ level organization, coelomate and bilaterally symmetrical animals
2. Body of the animal is circular consisting of anterior proboscis, a color and a long trunk.
3. Presence of open circulatory system
4. Gills serve the purpose of respiration and proboscis gland for excretion
5. Animals are dioecious, fertilization is external with indirect development
6. Organisms belonging to the phylum Hemichordata – Balanoglossus, Saccoglossus