Florida Representative Fossil
Sea Urchin (common name)
Echinoidea (scientific name)
Sea urchins are a diverse class of small, round, spiny creatures that have lived in oceans all over the world for millions of years. Sea urchins occur as black, brown, purple, red, and shades of green. They belong to the phylum Echinodermata. Sand dollars, sea lilies, and sea cucumbers are also echinoderms. However, unlike these organisms, sea urchins have calcium carbonate shells called tests covering their organs. This rigid test is made of plates and fossilizes rather easily in comparison to the delicate skeletons of other echinoderms.
This test is normally the only part of the organism that is preserved as a fossil, but the spines may also fossilize. The oldest sea urchin fossils ever discovered date from the late Ordovician period of the Paleozoic era, approximately 450 million years ago. Other sea urchin fossils reported from present-day China are said to be over 530 million years old from the Cambrian period of the early Paleozoic era.
Echinoid fossils occur in several formations of peninsular, northwest, and southern Florida. These fossils date from the Pliocene to Eocene epochs, ranging from 10,000 to 55 million years old. Florida has not named an official state fossil. The nearly statewide occurrence of sea urchin fossils make this fossilized sea creature a suitable representative of Florida’s paleontology.
The word urchin comes from the Middle English word for hedgehog and refers to the echinoderm’s appearance. The class Echinoideawas named in 1778 by German geologist and natural scientist Nathaniel Gottfried Leske.
Sea urchins are normally two to five inches (five to 12 cm) in diameter, and the largest individuals can reach up to 15 inches (38 cm). Like all echinoderms, sea urchins have five-fold radial symmetry, water-vascular systems, and hundreds of tiny tubular projections used for mobility and feeding. Most sea urchins have a mouth called Aristotle’s lantern, which is made of lips, a tongue, and calcium carbonate teeth. Echinoids feed on algae, sea grass, seaweed, and waste particles. Sea otters and lobsters in turn feed on sea urchins. Sea urchins also have movable spines used for protection and shade.
Only six species of echinoids are known to have survived the Permian–Triassic extinction event, which wiped out nearly 96 percent of all marine species and 70 percent of all terrestrial vertebrates living at the time. This mass extinction took place approximately 251 million years ago at the transition from the Paleozoic era to the Mesozoic era.
Humans eat sea urchin roe as sashimi or sushi; in Japanese this is known as uni. In the United States, red, purple, and green sea urchins are harvested for their roe and exported to Japan. Sea urchin roe and some species of sea urchin are served as delicacies or used in flavoring rich sauces such as Hollandaise and Béchamel, and in egg dishes such as omelets and soufflés.
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|Author: World Trade Press|