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The name urchin is an old word for hedgehog, which sea urchins resemble; they have archaically been called sea hedgehogs. [ 6 ] [ 7 ] The name is derived from the Old French herichun , from Latin ericius ('hedgehog').
The Diadematidae are a family of sea urchins. Their tests are either rigid or flexible and their spines are long and hollow. [2] Astropyga Gray, 1825 Astropyga radiata (Leske, 1778), extant; Astropyga pulvinata (Lamarck, 1816), extant; Astropyga magnifica (Clark, 1934), extant; Centrostephanus Peters, 1855 Centrostephanus asteriscus (Agassiz ...
Eucidaris tribuloides, the slate pencil urchin (named after slate pencil), is a species of cidaroid sea urchins that inhabits littoral regions of the Atlantic Ocean. As a member of the basal echinoid order Cidaroida , its morphological, developmental and molecular genetic characteristics make it a phylogenetically interesting species.
The primaries are pale grey, tipped with green and the secondaries are pale green. The test has a diameter of 7 cm (2.8 in) to 8 cm (3.1 in) and the spines are twice as long as this. [2] The sea urchin often has bits of algae, sponge or other organisms adhering to the spines. [2]
The Echinothurioida are an order of sea urchins in the class Echinoidea. Echinothurioids are distinguished from other sea urchins by the combination of a flexible test and hollow spines. The membrane around the mouth contains only simple plates, in contrast to the more complex mouth parts of their close relatives, the Diadematoida. They are ...
Its range extends from the Mediterranean Sea and North African coast to the Caribbean Sea and the Gulf of Mexico. [1] The depth range is between 40 and 210 metres (130 and 690 ft). Off Florida this urchin is usually found on algae or on broken coral substrates , particularly the rubble remains of dead ivory bush coral ( Oculina varicosa ).
One of the most notorious sea urchin mass deaths took place in the Caribbean Sea in 1983, affecting a black-spined urchin species called Diadema antillarum. At the time, scientists were unable to ...
Skeletogenesis begins in the early sea urchin blastula (9–10 hours post fertilization) when the primary mesenchyme cells (PMCs), the sole descendants of the large micromere daughter cells, [2] undergo an epithelial–mesenchymal transition (EMT) and break away from the apical layer, thus entering the blastocoel, [3] forming a cell cluster at the vegetal pole. [1]