Psammechinus miliaris
| Psammechinus miliaris | |
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| Psammechinus miliaris | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Echinodermata |
| Class: | Echinoidea |
| Superorder: | Echinacea |
| Order: | Camarodonta |
| Family: | Parechinidae |
| Genus: | Psammechinus |
| Species: | P. miliaris |
| Binomial name | |
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Psammechinus miliaris (P.L.S. Müller, 1771) |
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Psammechinus miliaris is a species of sea urchin in the family Parechinidae. It is sometimes known as the green sea urchin or shore sea urchin. It is found in shallow areas of the eastern Atlantic Ocean and the North Sea.
P. miliaris can reach a diameter of 5.75 cm (2.26 in). The test is globular, somewhat flattened dorso-ventrally, and up to five centimetres in diameter. It is covered in short, equi-length robust spines. The test and spines of shallow water specimens are purplish-brown but specimens from deeper water have a greenish test and pale coloured spines with purple tips. If individuals are transferred from one depth range to another, they retain their original colouration in their new location. On each ambulacral plate there are three pairs of tubercles each with a spine attached, the central one being a primary spine. On the ventral side, the orifices are relatively small and the buccal membrane is closely packed with thick plates with many pedicellariae but no spines. The globiferous pedicellariae are numerous but small and the tridentate pedicellariae are stout with broad blades.
P. miliaris occurs in the eastern Atlantic Ocean from Scandinavia south to Morocco, but not in the Mediterranean Sea. It is particularly common in the North Sea. It is mostly a littoral species but can be found from low tide mark down to a depth of one hundred metres. It is often found on or under Saccharina latissima, a large brown seaweed with which it shares its range. It occurs in a range of other habitats including under boulders and rocks, among seaweed, on rough ground such as oyster banks, in burrows in gravelly sediments and on the rhizomes of Zostera marina in seagrass meadows. The larvae often settle onto man-made structures such as ropes close to aquaculture facilities.
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Wikipedia