Echinoderms belong to the phylum Echinodermata having 5 classes namely Crinoidea (Sea lilies and Feather stars), Ophiuroidea (Brittle stars and basket stars), Asteroidea (Sea stars), Echinoidea (Sea urchins) and Holothuoidea (Sea cucumbers) (Fig. 8.11).
Q. What makes a echinoderm?
An echinoderm is an organism (all marine) that has a spiny skin. Most echinoderms have pentamerous radial symmetry, meaning they can be divided externally into five equal parts along a central oral/aboral axis. Echinoderms also have a water vascular system.
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Q. How would you know if an animal was an echinoderm?
Echinoderms (scientific name Echinodermata) are a major group of only marine animals. The name comes from the Greek word for “spiny skin”. Echinoderms have radial symmetry, many having five or multiples of five arms. They have a shell, made mainly of calcium carbonate, which is covered by skin.
Q. Is echinoderm a family?
Starfish, brittle stars, sea urchins, and sea cucumbers all belong to the family of echinoderms. These slow-moving, headless invertebrates are the only animals with bodies based on a five-pointed structure.
Q. How many stomachs does a sea star have?
two stomachs
Q. Do sea stars float?
But starfish don’t float – which isn’t the only difference…. When we say “Float like a starfish” we mean extend arms and legs to look like a starfish because that makes floating easier. And knowing how to float is a critical survival skill. But there would be all sorts of problems in being like a starfish.
Q. Why do sea stars have 2 stomachs?
The starfish has two stomachs. The cardiac stomach eats the food outside the starfish’s body. When the cardiac stomach comes back into the body, the food in it is transferred to the pyloric stomach. After the tube feet open the shell of its prey, the cardiac stomach is extended into the shell to pull the food inside.
