Sphaerechinus granularis

Sphaerechinus granularis is a species of sea urchin in the family Toxopneustidae, commonly known as the violet sea urchin,[2] or sometimes the purple sea urchin (though the latter is also a common name for a Pacific sea urchin Strongylocentrotus purpuratus). Its range includes the Mediterranean Sea and eastern Atlantic Ocean.[1]

Sphaerechinus granularis
Sphaerechinus granularis on Madeira
Scientific classification
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S. granularis
Binomial name
Sphaerechinus granularis
(Lamarck, 1816) [1]
Synonyms[1]
  • Echinus (Toxopneustes) albidus (L. Agassiz, 1841)
  • Echinus (Toxopneustes) brevispinosus (Blainville, 1825)
  • Echinus (Toxopneustes) granularis (Lamarck, 1816)
  • Echinus albidus L. Agassiz, 1841
  • Echinus brevispinosus Blainville, 1825
  • Echinus dubius Blainville, 1825
  • Echinus granularis de Lamarck, 1816
  • Echinus subglobiformis Blainville, 1825
  • Sphærechinus brevispinosus (Blainville, 1825)
  • Sphærechinus ovarius Lambert & Thiéry, 1914
  • Sphaerechinus roseus Russo, 1893
  • Strongylocentrotus granularis (Lamarck, 1816)
  • Toxopneustes brevispinosus (L. Agassiz, 1841)

Description

S. granularis is a large sea urchin, somewhat flattened dorsally and growing to fifteen centimetres in diameter. There are two distinct colour forms. The test is purple in both but one has purple spines and the other white. The spines are short and blunt, all the same length, and arranged neatly in rows.[3]

Distribution and habitat

S. granularis is found in the Mediterranean Sea and the eastern Atlantic Ocean, from the Channel Islands south to Cape Verde and the Gulf of Guinea. It favours sheltered locations and lives on rocks covered with seaweed or gravelly substrates. It is usually found in the neritic zone down to about 30 metres (100 ft),[3] but it is occasionally as 130 metres (430 ft).[4] It is also found in meadows of the seagrass Posidonia oceanica.[5]

Biology

S. granularis often covers itself with morsels of algae and shell fragments, which are held in place by the tube feet and by the claw-like structures known as pedicellaria.[6] It grazes on algae, especially encrusting coralline algae, seagrass blades and their epiphytic organisms and detritus.[7]

Spawning takes place at any time of year but the peak period is spring and early summer. Eggs and sperm are liberated into the water column, where egg fertilisation takes place. The larvae are planktonic. After several moults, the echinopluteus larva settles and undergoes metamorphosis before developing into a juvenile.

Ecology

In Tunisia, S. granularis is found living in association with two other species of sea urchins, Centrostephanus longispinus and Paracentrotus lividus. It is preyed upon by the starfish Marthasterias glacialis and Luidia ciliaris.[7]

Violet sea urchins in different colors near the island of Ugljan, Croatia

Use as food

The gonads of S. granularis are considered a delicacy in Italy, Provence[8] and Catalonia.[9]

References

  1. Sphaerechinus granularis (Lamarck, 1816) World Register of Marine Species. Retrieved 2011-08-26.
  2. Wood, Lawson (2011). Sea Fishes Of The Mediterranean Sea. London: Bloomsbury Natural History. p. 83.
  3. Picton, B.E. & Morrow, C.C. (2010) Sphaerechinus granularis (Lamarck, 1816). Encyclopedia of Marine Life of Britain and Ireland. Retrieved 2011-08-27.
  4. Vafidis, Dimitrios; Antoniadou, Chryssanthi; Ioannidi, Vassiliki (26 August 2020). "Population Density, Size Structure, and Reproductive Cycle of the Comestible Sea Urchin Sphaerechinus granularis (Echinodermata: Echinoidea) in the Pagasitikos Gulf (Aegean Sea)". Animals. 10 (9): 1506. doi:10.3390/ani10091506. PMC 7552135. PMID 32858926.
  5. Verlaque, M. (1981). "Preliminary data on some Posidonia feeders". Rapp. P.v. Ciesm Monaco. 2 (27): 201–02.
  6. Sphaerechinus granularis. European Marine Life. Retrieved 2011-08-27.
  7. "Purple Sea Urchin (Sphaerechinus granularis)]". Archipelagos Wildlife Library. Archived from the original on 30 March 2012. Retrieved 27 August 2011.
  8. "Sphærechinus granularis (Lamarck 1816)" (in French). Le Monde des Echinodermes. Retrieved 2011-08-27.
  9. Eckhardt, Robyn (2 March 2016). "On the Costa Brava of Spain, a Sea Urchin Quest". The New York Times. Retrieved 1 November 2022.
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