Little heart hedgehog
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Little Heart Hedgehog ( Echinocardium cordatum ) |
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| Echinocardium cordatum | ||||||||||||
| ( Pennant , 1777) |
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The little heart urchin ( Echinocardium cordatum ), often simply called heart sea urchin or heart urchin , is a type of heart urchin belonging to the sea urchins and is widespread in the north-eastern Atlantic .
features
The animals grow up to 6 cm. The heart-shaped shell is white or yellowish. Living animals wear a dense, fur-like dress made of yellow to brownish-yellow spines that lie close to the body and are directed towards the end of the body. These short and thin spines are soft, furry to the touch and are easily fragile, which is why the specimens found on the beach are rarely undamaged. The species belongs to the group of irregular sea urchins and does not have the five-pointed symmetry typical of echinoderms . Instead, the animals are bilaterally symmetrical and have a recognizable front and rear end.
distribution
The species is distributed in the northeast Atlantic, including the North Sea .
The species lives on the European coasts from the Portuguese Atlantic coast to the north of the Norwegian North Cape , but is absent off Iceland or Spitsbergen . It is widespread in the North Sea and along its coasts and is also found in the Kattegat down to the Danish islands, where it just barely reaches the Baltic Sea along the Swedish coast , but is absent in the rest of the Baltic Sea.
In the past, the species was considered cosmopolitan , as species from the Echinocardium cordatum species complex were also found in seas in other parts of the world, such as in the Mediterranean , off the United States , New Zealand , Australia , Japan , Korea , the Primorye region in Russia , South Africa , Madagascar , Indonesia and others. Moderate latitudes were preferred. Analyzes of the mitochondrial DNA have shown that these E. cordatum finds from around the world are five different mitochondrial clades whose geographical distribution has been confirmed to be in the north-eastern Atlantic, off Australia and New Zealand as well as off Japan, Korea and Russia. Three of these five clades also live on the European coasts, one of which occurs only in the Mediterranean and one from the Mediterranean to the Spanish Atlantic coast. Morphological studies could also show morphological differences between the clades, which could be confirmed as different cryptospecies by analysis of the nuclear DNA.
The little heart urchin was found below the intertidal zone at depths of 0-230 m, in the littoral and especially in the Neritic zone , where it lives buried 10-20 cm deep in sandy to muddy soils. Sediment sizes of 200-300 µm with a low sludge content are preferred.
Way of life
The animals live buried in the sea floor, which is why living specimens are rarely found. However, the empty and fragile skeletons of dead animals are regularly washed free and washed up on beaches. In the ground, the animals are in slime-covered caves with an opening to the surface. A long suction thread keeps this opening open so that the animals are supplied with fresh water. The spines also help to hold air in, to prevent a lack of oxygen. The animals, which usually live in colonies (up to 20 specimens per square meter, in extreme cases up to 200) do not stay in place, but move slowly through the ground in order to absorb the sand with the nutrients adhering to it. Sinking detritus is also taken up through the opening to the surface. The small heart hedgehog and the closely related species of the species complex form large populations in their range and are among the most common heart hedgehog species.
Reproduction takes place in spring when the two sexes release their gametes into the water column. The pluteus larvae form part of the zooplankton . The metamorphosis from larva to adult sea urchin takes place around 39 days after fertilization. The lifespan of the Little Heart Hedgehog can be more than ten years.
Elongated lentil shells ( Tellimya ferruginosa ) sometimes live as commensals in the “constructions” of the hedgehog in the sand . The flea shrimp Urothoe marina was also detected here more frequently.
Taxonomy
The species was first described by Thomas Pennant in 1777 as Echinus cordatum . Further synonyms of the species are:
- Amphidetus cordatus ( Pennant , 1777)
- Amphidetus kurtzii Girard , 1852
- Amphidetus novaezelandiae Perrier , 1869
- Amphidetus zealandicus ( Gray , 1851)
- Amphidotus cordatus ( Pennant , 1777)
- Echinocardium australe Gray , 1851
- Echinocardium cordatus ( Pennant , 1777)
- Echinocardium kurtzii ( Girard , 1852)
- Echinocardium sebae Gray , 1825
- Echinocardium stimpsonii A. Agassiz , 1864
- Echinocardium zealandicum Gray , 1851
- Echinus cordatus Pennant , 1777
- Spatangus arcuarius Lamarck , 1816
- Spatangus cordatus ( Pennant , 1777)
literature
- Georg Quedens: Beach and Wadden Sea - animals and plants on the North and Baltic Seas - a biotope guide. 6th revised edition. BLV Verlagsgesellschaft, Munich 1997, ISBN 3-405-15108-2 , p. 90.
- Ursula Stichmann-Marny, Wilfried Stichmann, Erich Kretzschmar: The new cosmos animal and plant guide. With a special section: Vacation areas in Europe. 4th edition. Franckh-Kosmos Verlag, Stuttgart 2000, ISBN 3-440-08041-2 , p. 444.
Web links
- Echinocardium cordatum . In:WoRMS - World Register of Marine Species. Retrieved May 28, 2021.
Individual evidence
- ↑ E. Egea, B. David, T. Choné, B. Laurin, JP Féral, A. Chenuil: Morphological and genetic analyzes reveal a cryptic species complex in the echinoid Echinocardium cordatum and rule out a stabilizing selection explanation. In: Molecular Phylogenetics and Evolution. Vol. 94, Part A, 2016, pp. 207-220. doi: 10.1016 / j.ympev.2015.07.023 .
- ↑ Echinocardium cordatum (Pennant, 1777) in GBIF Secretariat (2021). GBIF backbone taxonomy. Checklist dataset, doi: 10.15468 / 39omei , accessed via GBIF.org on May 28, 2021.