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Adult sea urchins are usually well protected against most predators by their strong and sharp spines, which can be venomous in some species. [32] The small urchin clingfish lives among the spines of urchins such as Diadema ; juveniles feed on the pedicellariae and sphaeridia, adult males choose the tube feet and adult females move away to feed ...
Fossil of Acrocidaris, an extinct sea urchin Echinoid fossils are the fossilised remains of sea urchins , spiny marine invertebrates that live on the seabed. Humans have been interested in these fossils for millennia, have considered them lucky, have imbued them with magical powers and linked them to their deities .
Download as PDF; Printable version; In other projects ... The subclass Euechinoidea includes almost all living species of sea urchin, with fossil forms going back as ...
Cidaris cidaris has a small central test from which project a number of long, blunt, widely separated primary spines and a dense covering of short secondary spines. 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 ...
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 ...
These tubercles hold massive spines, thick, strong and often very long, and showing sometimes odd shapes (thorny spines, fans, clubs, Christmas trees [1]...). [ 2 ] [ 3 ] The order Cidaroida is the basalmost of current sea urchins, and most of the species included in this family are abyssal, even if a handful of species remain quite common in ...
These days, long-spined sea urchins are known as the gardeners of the sea. They tend the algae on the coral reefs they call home, making sure it never overwhelms their hosts. Spotting one on the ...
Diadema paucispinum is a small sea urchin with very long, moveable spines which are slender and sharply pointed. They can be up to 25 cm (10 in) long and about four times the diameter of the test. The primary spines are bluish-black in colour, often with pale bands in younger individuals.