Comment of Echinus
Distribution:
Echinus is a genus of sea urchins, a group of marine animals with a spiny outer skeleton. Echinus is widely distributed in the Atlantic, Mediterranean and pacific oceans.
Habit and Habitat:
Echinus is marine, found in the sea in rocky places.
General character:
- Echinus is commonly known as sea urchin.
- Body is globular in shape, somewhat Flattened at the two poles Forming distinct oral and aboral pales.
- Body is enclosed in a rigid globular shell or corona Formed of closely Fitted calcareous plates.
- Entire surface of the animal except the peristome and periproct is covered with spines articulated to the shell.
- At the aboral pole is a much smaller, aperture, the annus surrounded by periproducts.
- Numerous podia or tube Feet protect from the surface among the spines.
- Sexes are separate. Gonads are five large masses.
Economic Importance:
Echinus:- Edible (gonads of both the male and female sea urchins) are eaten. Sea urchin species with orange gonads are preferred.
Diagram of Echinus
Comment of Cucumaria:
Distribution:
Cucumaria is cosmopolitan in distribution. This is commonly found in Europe, U.S.A and India.
Habit and Habitat:
Cucumaria is marine. They are found at all depth from shallow to vary deep water and are primarily of benthic and sluggish habit. Some live in rocky crevices and crannies and among corals and seaweeds, but the majority are found on sandy bottoms, either fully exposed or wholly or partially in mud.
General characters:
1) Cucumaria is commonly known as sea cucumber.
2) Body is elongated, cylindrical with the mouth and anus at opposite ends.
3) Mouth bears ten highly dendritic or branched tentacles.
4) The smooth, thin and collar-like region of the base of tentacles is known as introvert.
5) Anus is terminal placed on the aboral end.
6) Respiratory trees are present .
7) Sexes are separate ,gonads are arranged in two tufts.
Economic Importance:
Cucumaria:- Serve a useful role in the marine ecosystem as they help recycle nutrients, breaking down detriful and other organic matter after which bacteria can continue the degradation process.
Diagram of Cucumaria:
