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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 .
Sea urchin tests showing the ball parts of the ball and socket joints that articulate with the spines Iconaster longimanus, the icon seastar, showing plate ossicles Ossicles have a variety of forms including flat plates, spines, rods and crosses, and specialised compound structures including pedicellariae and paxillae .
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 ...
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 ...
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 ...
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 ...
Close-up of Asthenosoma varium, showing distinctive spines. Asthenosoma varium is a large sea urchin, hemispherical in shape, and growing to a diameter of 25 cm (10 in). ). The plates from which the test is formed are not joined rigidly together, as is the case in most sea urchin