`star` Introduction
`star` Characteristic features
`star` Development


● `color{Brown}"Members"`: This phylum includes animals with an endoskeleton of `color{Violet}"calcareous ossicles"` and skin of `color{Violet}"calcareous spines"` and hence, the name `color{Violet}"Echinodermata (Spiny bodied)"`.

● `color{Brown}"Habitat""`: They are all marine. Generally are bottom dwelling and slow moving.

● `color{Brown}"Basic Features"`: They have `color{Violet}"organ-system"` level of organization. The adult echinoderms are `color{Violet}"radially symmetrical"` but larvae are bilaterally symmetrical. They are `color{Violet}"triploblastic"` and `color{Violet}"coelomate"` animals.

● `color{Brown}"Examples"`: 𝘈𝘴𝘵𝘦𝘳𝘪𝘢𝘴 (Star fish), 𝘌𝘤𝘩𝘪𝘯𝘶𝘴 (Sea urchin), 𝘈𝘯𝘵𝘦𝘥𝘰𝘯 (Sea lily), 𝘊𝘶𝘤𝘶𝘮𝘢𝘳𝘪𝘢 (Sea cucumber) and 𝘖𝘱𝘩𝘪𝘶𝘳𝘢 (Brittlestar).


● `color{Brown}"Body shape"`: They are star like, cylindrical, melon like or disc like.

● `color{Brown}"Skin"`: Skin of echinoderms contains `color{Violet}"calcareous spines"`, `color{Violet}"pedicellariae"` (minute pincer like structure that clears the body of debris) and endoskeleton consists of `color{Violet}"calcareous plate"` (Ossicle).

● `color{Brown}"Digestive system"`: It is `color{Violet}"complete"` with mouth on the lower (ventral) side and anus on the upper (dorsal) side.

● `color{Brown}"Water vascular system"`:
`star` The most distinctive feature of echinoderms is the water filled `color{Violet}"ambulacral or water vascular system"` with tube feet to help in locomotion, capture and transport of food and respiration.

`star` Structures like `color{Violet}"Madreporite"`, `color{Violet}"tube feet"`, `color{Violet}"radial canals"`, `color{Violet}"tiedmann body"` and `color{Violet}"stone cana"`l are also found in water vascular system.

● `color{Brown}"Respiration"`: It takes place by body surface or `color{Violet}"gills called dermal branchiae"`.

● `color{Brown}"Circulation system"`: It is reduced and `color{Violet}"open"` type

● `color{Brown}"Excretory system"`: `color{Violet}"Absent"`; nitrogenous waste ammonia `color{Violet}"diffuses"` out through body surface.

● `color{Brown}"Nervous system"`: `color{Violet}"Simple"` and less developed. They don't have head and brain


● Sexes are `color{Violet}"separate"`.

● Reproduction is `color{Violet}"sexual."`

● Fertilisation is usually `color{Violet}"external"`.

● Development is `color{Violet}"indirect"` with free-swimming larva ( like Auricularia in sea cucumber, Doliolaria in Sea lily and Bipinnaria in star fish)

`color{Green}♣ color{Green} "Just for Curiousity"`
●Few echinoderms like star fish have great `color{Violet}"power of regeneration"`. They break off their arms for defense purpose by a process known as `color{Violet}"Autotomy"`.

● Sea cucumbers in a frightened state `color{Violet}"vomit out viscera"` (internal organ) by a process known as `color{Violet}"Evisceration"`.