Phylum EchinodermataThe Easiest Review

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Phylum Echinodermata Review

1. What are some representatives of the echinoderm phylum?

Starfishes, sea cucumbers (holothurians), sea urchins and brittle stars are examples of echinoderms.

Phylum Echinodermata - Image Diversity: echinoderms starfish sea cucumber sea urchin brittle star

2. Under which environments do echinoderms live?

Echinoderms are marine animals, they live in salt water.

3. What are the basic morphological features of echinoderms?

Echinoderms, as the name indicates (echino = spiny, derma = skin), are creatures with spines originated from an endoskeleton. Their endoskeleton is made of calcareous plaques that besides spines contain pedicellaria, small pincers used to clean the body and to help the capturing of prey. They also present a hydrovascular system known as the ambulacral system. Adult echinoderms have pentaradial symmetry; the radial symmetry in these animals is secondary, present only in adults.

4. How can the endoskeleton of echinoderms be characterized in comparison to analogous structures present in vertebrates, arthropods and molluscs?

The echinoderm skeleton is internal, i.e., it is an endoskeleton. It is made of calcium carbonate (calcareous).

Vertebrates also have internal skeleton made of bones and cartilages. Arthropods have an external carapace made of chitin, a chitinous exoskeleton. Some molluscs present a calcareous shell that works as exoskeleton.