Paracentrotus lividus Green Sea Urchin Sea Hedgehog Echinoderma Echinozoa Echinoidea Regularia Parechinidae

Paracentrotus lividus Green Sea Urchin 3.5-4.5 cm Regular Sea Hedehog Echinoderma Echinozoa Echinoidea Regularia Parechinidae.
Family: Parechinidae.
Common name: Common Sea Urchin or Rock Sea Urchin.
Syn. Echinus (Toxopneustes) complanatus, Echinus (Toxopneustes) concavus, Echinus (Toxopneustes) lividus, Echinus lithophagus, Echinus purpureus, Echinus vulgaris, Euryechinus lividus, Microcordyla asteriae, Strongylocentrotus lividus, Toxocidaris livida.

The sea urchin Paracentrotus lividus (Lamarck, 1816) is a sea urchin of the Parechinidae family.
It is very common throughout the Mediterranean Sea and in the eastern Atlantic, from Scotland to the Canary Islands. It lives on rocky seabeds and populates the meadows of Posidonia oceanica, from 0 to 30 meters deep.
The newly born sea urchin appears in the form of a small gelatinous swimming larva of a few millimeters, with bilateral symmetry, called pluteus, from whose body 4 to 6 arms branch out. This stage lasts from 4 to 6 weeks, during which the pluteus is transported by sea currents.
Like other echinoderms, the adult has pentaray symmetry with a calcareous skeleton, improperly called a shell, which can reach 7 cm in diameter, equipped with long mobile spines and, on the ventral surface, with many small protrusions with sucker-like ends, called ambulacral pedicels, which allow it to move. The color can be various shades of purple, brown and greenish. The mouthparts (lantern) are made up of 5 mobile skeletal elements, each equipped with a tooth.
To breathe, it uses small gills that continuously pump water.
It feeds on algae but also on small animals and sponges, and is among the few organisms capable of feeding directly on the leaves of Posidonia oceanica mainly during the night hours. Even if it lives in the less deep and therefore brighter areas, it needs shade and therefore covers itself with pieces of Posidonia, pebbles and shells, which are held with the suction-cup peduncles.
In nature, the sea urchin has among its main predators the white sea bream and the gilt-head bream that despite their spines, thanks to the powerful teeth that these species possess, are able to break the shells and devour their contents but curiously also the entire shell, the white sea bream in particular, no one knows why, prefers to swallow the lantern too.