Carefully try to pick up the sea star and observe the tube feet in motion. They are characterized by a unique water vascular system connected to tube feet which are used for locomotion, gas exchange and feeding. Echinodermata are exclusively marine organisms. They have a very simple nervous system and no circulatory system. Echinodermata are so named owing to their spiny skin (from the Greek echinos meaning spiny and dermos meaning skin), and this phylum is a collection of about 7,000 described living species. Describe the blastula, gastrula and larval stages: Echinoderms are the closest relatives of the chordates (which includes us) but are very different in many ways. Observe sea star developmental stages with the compound microscope. Many adult echinoderms have pentaradial symmetry (5 arms on a sea star, 5 rows of tube feet on a sea cucumber), but their larval forms show bilateral symmetry. As such, they have been known to become a bit of a pest on mussel and oyster beds Starfish feed on shellfish by pulling the shells open with their arms. They are active predators, feasting on bivalves such as mussels and clams. Look closely at the live sea star under the dissecting scope to observe this. The common starfish is highly common in UK seas, found in rockpools and out at sea to depths of at least 600m. Their name refers to their spiny skin, which is actually an endoskeleton composed of internal plates with living tissue on the outside. Phylum Echinodermata (sea stars, sea urchins, sea cucumbers): observe live sea star Echinoderms are very strange animals, found exclusively in the marine environment.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |