''Arbacia lixula'', the black sea urchin, is a species of
sea urchin
Sea urchins () are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to . The spherical, hard shells (tests) of ...
from Europe.
Description
It is a medium-sized sea urchin, characterized by its deep black color and its hemispherical shape. All of its spines are roughly the same size (no "secondary spines"), and worn erected (never dishevelled when in the water). The anus on the top is surrounded by four plates forming an anal valve. The oral face is nearly naked, the mouth being surrounded by soft, dark-greenish skin.
[ZIEMSKI Frédéric, André Frédéric, in: DORIS, 15/5/2014]
Arbacia lixula (Linnaeus, 1758)
Image:Arbacia lixula 03.JPG, Profile
Image:Black Sea Urchin (Arbacia lixula) in Croatia.jpg , Sticking on a rock
Image:Sea urchin upside down.JPG, Oral face
Image:Arbacia lixula.JPG, ''In situ''
This species can be confused with the purple sea urchin ''
Paracentrotus lividus
''Paracentrotus lividus'' is a species of sea urchin in the family Parechinidae commonly known as the purple sea urchin. It is the type species of the genus and occurs in the Mediterranean Sea and eastern Atlantic Ocean.
Description
''Paracentr ...
'', but the latter is never really black (though often very dark), has more dishevelled spines of many lengths, covers itself with debris, has spines around the mouth and no anal valve, and does not live exposed on the cliffs.
Habitat and geographical range
This species can be found on the coast of the
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the ea ...
and Macaronesian Islands (
Azores
)
, motto =( en, "Rather die free than subjected in peace")
, anthem= ( en, "Anthem of the Azores")
, image_map=Locator_map_of_Azores_in_EU.svg
, map_alt=Location of the Azores within the European Union
, map_caption=Location of the Azores wi ...
,
Madeira
)
, anthem = ( en, "Anthem of the Autonomous Region of Madeira")
, song_type = Regional anthem
, image_map=EU-Portugal_with_Madeira_circled.svg
, map_alt=Location of Madeira
, map_caption=Location of Madeira
, subdivision_type=Sovereign st ...
,
Canary Islands
The Canary Islands (; es, Canarias, ), also known informally as the Canaries, are a Spanish autonomous community and archipelago in the Atlantic Ocean, in Macaronesia. At their closest point to the African mainland, they are west of Morocc ...
), and less commonly, on the Atlantic coast of Western Africa and the Brazilian coast.
It is found typically at shallow waters, at depths from 0 to 30 m, in rocky shores. It has a good resistance to hydrodynamism due to a good attachment strength to rocks.
Biology
This species feeds mainly on crustose
red algae
Red algae, or Rhodophyta (, ; ), are one of the oldest groups of eukaryotic algae. The Rhodophyta also comprises one of the largest phyla of algae, containing over 7,000 currently recognized species with taxonomic revisions ongoing. The majority ...
and small
filamentous algae
Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular micr ...
. In a marine reserve in the Mediterranean, its population increased by a factor over 10 between 1983 and 1992, from eight to 100 individuals per meter
2. High seawater temperatures are thought to favour this species. When it was excluded from an area of the reserve, the density of filamentous algae increased.
See also
* ''
Arbacia spatuligera''
References
External links
EchinoidsExcellent photo of the test the same site.
*
Animals described in 1758
Arbacioida
Taxa named by Carl Linnaeus
{{echinoidea-stub