Heart hedgehog
| Heart hedgehog | ||||||||||||
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Violet Heart Hedgehog ( Spatangus purpureus ) |
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| Scientific name | ||||||||||||
| Spatangoida | ||||||||||||
| Claus , 1876 |
Heart urchins (Spatangoida), also heart sea urchins , belong to the sea urchins , but are rarely seen because they live buried in the sand in the sea floor. Only a tube-like opening created by them at the top enables water to be exchanged. The heart urchins are covered like hair with fine, curved spines, which create a cavity in the sediment that can be filled with water.
features
Heart hedgehogs are bilaterally symmetrical and usually have a heart-shaped, but at least oval outline. Some species are also elongated. In contrast to the sand dollars , their top is always arched high. The shell is thin, the spines hair-like and curved. The mouth is on the front edge, the anus either on the rear edge or on the oral side. The chewing apparatus with jaws and teeth is only put on in youth and later regressed. The gonads are also reduced to four, sometimes three or two. Heart hedgehogs have different types of ambulacral feet .
Way of life
Like the sand dollars, the hedgehogs live buried in the ground, but penetrate deeper into the ground (up to 20 centimeters). Deep-living species maintain a connection to the sand surface through a breathing tube formed by mucus when they are buried.
Systematics
Heart urchins belong to the class of sea urchins (Echinoidea). There are over 100 types. As irregular sea urchins (Irregularia), heart sea urchins are assigned to the superorder Atelostomata .
- Suborder Asterostomatina
- Family Asterostomatidae
- Subordination Hemiasterina AG Fischer, 1966
- Family Aeropsidae
- Family Hemiasteridae Clark, 1876
- Family Palaeostomatidae
- Family Pericosmidae
- Schizasteridae Lambert family , 1905
- Subordination Micrasterina AG Fischer, 1966
- Family Brissidae Gray, 1855
- Loveniidae Lambert family , 1905
- Family Spatangidae Gray, 1825
- Suborder Toxasterina
- Family Toxasteridae
literature
- Volker Storch, Ulrich Welsch: Systematic Zoology . G. Fischer, Stuttgart 1997, ISBN 3-437-25160-0 .
- H. Füller, H.-E. Gruner, G. Hartwich, R. Kilias, M. Moritz: Urania Tierreich, Invertebrates 2 (Annelida to Chaetognatha) . Urania-Verlag, Leipzig 1994, ISBN 3-332-00502-2
Web links
- Integrated Taxonomic Information System Spatangoida Claus, 1876
- The Echinoid Directory (Natural History Museum London): http://www.nhm.ac.uk/our-science/data/echinoid-directory/