The Skeletal system of Echinodermata
Most, if not all, Echinodermata live in the bottom of the ocean. Approximately 13,000 different species make up the Echinodermata Phylum, some even dating all the way back to the mesozoic period. What makes this phylum different from all the others is that it has a mesodermal Skeleton, which is stiffened by calcification. Unlike with exoskeletons, Echinodermata's skeletons grow with the body.
Star Fish (Asteroidea)
Star fish have an endoskeleton (internal) that is mainly composed of calcium carbonate plates and other proteins. These plates are called ossicles. These ossicles can take the form of many different things, such as spines and granules. In between the ossicles are holes, called tube feet, that can help the starfish eat, move, and defend itself from predators.
Star fish have an endoskeleton (internal) that is mainly composed of calcium carbonate plates and other proteins. These plates are called ossicles. These ossicles can take the form of many different things, such as spines and granules. In between the ossicles are holes, called tube feet, that can help the starfish eat, move, and defend itself from predators.
Sea Urchin (Echinoidea)
Also posses calcium carbonate, but it is either embedded or protrudes from the body wall giving it a spiky appearance. Like in the Star fish it has tube feet so it can eat, move, and defend itself. Have a hemispherical shape from mostly leading a sedentary lifestyle. The test of a Sea Urchin is made up of ten parts. Five of them have tube feet and the others do not. It can move itself by pushing against the ground with its spines and tube feet.
Also posses calcium carbonate, but it is either embedded or protrudes from the body wall giving it a spiky appearance. Like in the Star fish it has tube feet so it can eat, move, and defend itself. Have a hemispherical shape from mostly leading a sedentary lifestyle. The test of a Sea Urchin is made up of ten parts. Five of them have tube feet and the others do not. It can move itself by pushing against the ground with its spines and tube feet.
Sea Cucumber (Holothuroidea)
Sea cucumbers are pentaradial symmetrical, but since they don't move often it causes on side to become flat and the other rounded. This have caused them to develop bilateral symmetry. They posses five ambulacral strips running along their body, from mouth to anus. Their tube feed are extended and withdrawn from these strips.
Sea cucumbers are pentaradial symmetrical, but since they don't move often it causes on side to become flat and the other rounded. This have caused them to develop bilateral symmetry. They posses five ambulacral strips running along their body, from mouth to anus. Their tube feed are extended and withdrawn from these strips.