Echinoidea

See also: Sea urchin

The Echinidea (called sea urchins , hedgehog of sea or sweet chestnut of sea ) are creatures of thorny Mer living in all the Océan S of the world. The adult intermediate size is between 3 and 14 centimetres. Certain species have poisonous prickles.

They are Invertébré S sailors of the junction of the Echinodermata (Échinodermes), of the Greek ekhinos , “spine” and derma “derm”. They are close relatives of the cucumbers of sea and starfishes.

Description

Their spherical body is protected by a shell hard or entirely covered with sharp-edged spine S. The spines fall after death from the animal. The naked shell is called a test.

They move slowly by using their mobile spines and their Podia S or Pseudopode S (small tubes located between the spines, filled with water and which makes suction cup at their end). These podias constitutes the apparatus ambulacraire sea urchin.

These animals scrape and shred the plants which paper the sea-bed using their mouth provided with jaws special, located under their lower face. This apparatus masticator bears the name of “ lantern of Aristote ”; it is composed of five teeth able to dig a tender rock.

The giant red sea urchin ( Strongylocentrotus franciscanus ), whose size can exceed 18 cm in diameter, is one of the largest species of sea urchins in the world. It is armed with spines being able to reach 8 cm; its color varies dark red in Burgundy

The sea urchin (sweet chestnut of the seas) common of the European littoral names Paracentrotus lividus .

Systematic

Place des sea urchins in the animal world

List subclasses

According to ITIS:
  • subclass Euechinoidea Bronn, 1860
    • superorder Atelostomata Zittel, 1879
      • order Cassiduloida Claus, 1880
      • order Spatangoida Claus, 1876
    • superorder Diadematacea Duncan, 1889
      • order Diadematoida Duncan, 1889
      • order Echinothurioida Claus, 1880
      • order Pedinoida
    • superorder Echinacea Claus, 1876
      • order Arbacioida Gregory, 1900
      • order Echinoida Claus, 1876
      • order Phymosomatoida
      • order Salenioida
      • order Temnopleuroida Mortensen, 1942
    • superorder Gnathostomata Zittel, 1879
      • order Clypeasteroida A. Agassiz, 1872
      • order Holectypoida Ducan, 1889
  • subclass Perischoechinoidea Me coy, 1849
    • order Cidaroida Claus, 1880

Sea urchin and the Man

Consumption of sea urchin

See also: Oursinade

All the sea urchins are not consumable. With diamond-pointed punches, one cuts out with middle height the carapace, on the basis of the soft zone deprived of prickles around the mouth. One consumes the five sexual glands i.e. the coral and the liquid which surround them. To be access, there is necessary to remove the mouth and the digestive system (the lantern of Aristote). The believed coral is eaten. According to the season, the coral is more or less agglomerated and its color goes from greenish to dark red.

They are consumed in many countries of the world. Fishing and the sale are prohibited from May to September in France

The sea urchin and research

The sea urchin is a model very much used for research. To carry out a fecundation in laboratory is relatively simple.

  • In ecotoxicology: the Larves of sea urchins (called pluteus, in form of Eiffel Tower) have deformities if the concentrations of pollutants in water exceed a certain threshold. In the same way, the percentage of fertilized Ovocytes decreases with the increase in the pollutants in the medium. One can thus use the sea urchins as indicators of Pollution of the medium. The prickles of the sea urchins can also be analyzed in order to analyze the Biomécanique of it the most polluted places.

  • In cellular Biology fundamental and applied. Once the fertilized ovocyte, divisions of the Cell-egg are easy to observe under the microscope and are synchronized. The cell-egg of sea urchin is thus an ideal tool for the study of the mechanisms of cellular division and beyond, of the disordered states which can lead to the development of Cancers.

See too

External references

External bonds

  • Course on Echinodermata
  • Research laboratory on the mechanisms of cellular division
  • Pages on the lantern of Aristote
  • Site on Echinodermata (which treats sea urchins) MNHN and LILY

Simple: Sea urchin

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