Echinoderms are animals with spiny skin
. Echinoderms are also Eukaryotic,
Deuterostomes with a coelom
This phylum includes starfish, brittle
stars, sea cucumbers, sea lilies, sea urchins, sand dollars, feather stars and sea daisies.
All of these animals are bilaterally symmetrical with radial symmetry as a
In the development of echinoderms the larva stage has bilateral
The bilateral larva develops into a radial adult.
All echinoderms body
structure includes a hard internal skeleton made of calcium and a water vascular
system which includes their tube feet.
Tube feet are involved in locomotion, feeding
and gas exchange.
Echinoderms are usually gonochoric with external fertilization. They
inhabit marine environments. This phylum is divided into six classes, Asteroidea (Sea
stars), Ophiuroidea (Brittlestars), Echinoidea (Sea urchins and Sand dollars), Crinoidea
(Sea Lilies and Feather stars), Holothuroidea (Sea cucmbers) and Concentricycloidea
We will observe animals from Classes Asteroidea, Ophiuroidea,
Crinoidea, Echinoidea and Holothuroidea.
, are sea stars or starfish.
Sea star external body structure
usually consist of five arms,
a central disc, hard skeleton, spiny skin, tube feet, a
madreporite on the aboral surface and the mouth on the oral surface.
The arms extend
from the central disc and are composed of connected calcareous ossicles which are a part
of the internal skeleton.
Sea stars are carnivores or scavengers.
They consume Bivalves,
gastropods, crustaceans, polychaetas as well as echinoderms.
These animals are able to
regenerate damaged body parts.