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Sand dollars diverged from the other irregular echinoids, namely the cassiduloids, during the early Jurassic, [5] with the first true sand dollar genus, Togocyamus, arising during the Paleocene. Soon after Togocyamus, more modern-looking groups emerged during the Eocene. [1] Sand dollars are small in size, averaging from 80 to 100 mm (3 to 4 ...
Clypeasteridae is a family of sea urchins in the order Clypeasteroida.This family was first scientifically described in 1835 by the Swiss-American biologist Louis Agassiz.. The clypeasteridae also known as the sand dollar, are round and semi-flat organisms with spines lining the underside of the body and elongated genital papillae aiding its survival and reproduction.
Clypeaster australasiae, the Australasian sand dollar, is a species of sea urchins of the family Clypeasteridae. Their armour is covered with spines. Their armour is covered with spines. Clypeaster australasiae was first scientifically described in 1851 by Gray.
The tests (shells) of these sand dollars are round, flat and disc-like, typically measuring 3 inches (7.6 cm) in diameter. The growth rate for this animal is between 3.5 to 6 mm/yr in the latter 5 years of their lifespan, and the lifespan is typically around 8 years. [2]
Dendraster excentricus, also known as the eccentric sand dollar, sea-cake, biscuit-urchin, western sand dollar, or Pacific sand dollar, is a species of sand dollar in the family Dendrasteridae. It is a flattened, burrowing sea urchin found in the north-eastern Pacific Ocean from Alaska to Baja California .
Mellita quinquiesperforata (Leske, 1778) is a tropical species of sand dollar, a flat, round marine animal related to sea urchins, starfish, and other echinoderms. They can be found along the eastern coast of the United States and the coast of Brazil. [1] Live M. quinquiesperforata (underside)
In the June 15, 1833, issue of the Baltimore Saturday Visiter, its publishers Charles F. Cloud and William L. Pouder announced prizes of "50 dollars for the best Tale and 25 dollars for the best poem, not exceeding one hundred lines", submitted by October 1, 1833. Poe submitted "MS. Found in a Bottle" along with five others.
Some burrowing sand dollars have an elongated papilla that enables the liberation of gametes above the surface of the sediment. [2] The gonads are lined with muscles underneath the peritoneum, and these allow the animal to squeeze its gametes through the duct and into the surrounding sea water, where fertilization takes place.