Spatangoida

Purple Heart Hedgehog ( Spatangus purpureus )

Heart Hedgehog ( Spatangoida ), and heart urchins belong to the sea-urchins, but are rarely seen because they live buried in the sand at the sea bottom. Only one of them created, tube-like opening at the top allows water exchange. The Heart Hedgehogs are covered with fine hair- like, curved spines, which increase the cavity in the sediment and thus these can fill with water.

Features

Heart Hedgehogs are bilaterally symmetrical and have a mostly heart-shaped, but at least oval outline. Some species are also elongated. Your top is but, in contrast to the sand dollar, always arched high. The shell is thin, the spines hair -like and bent. The mouth is located at the front edge of the anus mostly on the oral side. The masticatory apparatus with jaws and teeth is applied only in adolescence and later regressed. The gonads are sometimes three or two to four reduced. Heart Hedgehogs have different types of feet.

Way of life

As the sand dollar live the heart hedgehog in the ground dug, but penetrate deep into the soil (up to 20 cm). Deep living species maintained by a formed by mucus when burying breathing tube connection to the sand surface.

System

Heart Hedgehogs belong to the class of sea urchins ( Echinoidea ) on. There are over 100 species. As irregular sea urchins ( Irregularia ) heart urchin of the superorder Atelostomata are allocated.

• Subordination Asterostomatina Family Asterostomatidae

• Family Aeropsidae
• Family Hemiasteridae Clark, 1876
• Family Palaeostomatidae
• Family Pericosmidae
• Family Schizasteridae Lambert, 1905

• Family Calymnidae
• Family Holasteridae
• Family Pourtalesiidae
• Family Urechinidae

• Family Brissidae Gray, 1855
• Family Loveniidae Lambert, 1905
• Family Spatangidae Gray, 1825

• Family Neolampadidae

• Family Toxasteridae