Spatangoida
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The order Spatangoida contains the sea urchins known as heart urchins. Their bodies are shaped like elongated ovals, and they are set apart by having the mouth at one end and the anus at the other. This arrangement gives them bilateral symmetry and a clear front side, unlike most other sea urchins.
The placement of the mouth and anus is what creates the characteristic heart-like outline that inspired their common name. Heart urchins lack a feeding lantern, and their petaloids are often set into grooves. This order is fairly diverse, containing many different species.
Scientific classification
- KingdomAnimalia
- PhylumEchinodermata
- ClassEchinoidea
- OrderSpatangoida
Named by L. Agassiz, 1840
Sources: Wikipedia taxobox: Spatangoida (CC BY-SA 4.0)
Quick Facts
- Common name
- heart urchins
- Body form
- elongated ovals
- Symmetry
- bilateral
- Distinctive features
- mouth at one end, anus at the other
- no feeding lantern
- petaloids sunk into grooves
- Diversity
- relatively diverse order with a number of varying species
Facts from the source article.
Background
The heart urchins are members of the order Spatangoida of sea urchins. Their body are somewhat elongated ovals in form, and are distinguished by the mouth being placed towards one end of the animal, and the anus towards the other. As a result, unlike most other sea urchins, heart urchins are bilaterally symmetrical, and have a distinct anterior surface.
The presence and position of the mouth and anus typically give members of this group the distinct 'heart' shape from which they get their common name. Heart urchins have no feeding lantern, and often have petaloids sunk into grooves. They are a relatively diverse order, with a number of varying species.
More in Sea Urchins
Sources
Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.
- Wikipedia: Spatangoida (CC BY-SA 4.0).
- Word definitions: the Codexery glossary, each quoted from its Wikipedia article.
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