Sand Dollar (fossil)

Object/Artifact

-

Crater Rock Museum

Name/Title

Sand Dollar (fossil)

Entry/Object ID

78.57.128

Description

Description: Kingdom: Animalia Phylum: Echinodermata Class: Echinoidea Subclass: Euechinoidea Superorder: Gnathostomata Order: Clypeasteroida Genus: Clypeus Species: Ploti Common Name: Sand Dollar Age: Unknown Location: Found in Inferior Odite: Cheltenham, Gloustershire, England Description: One irregular echinoid with a petaloid ambulacral area and bilateral symmetry, showing the characteristic five-star pattern on shell with an oblong indentation in the shell. Color is light orange to beige. Physical Characteristics: Echinoderms (Phylum Echinodermata) are a phylum of marine animals. Echinoderms are found at every ocean depth, from the intertidal zone to the abyssal zone. Aside from the problematic Arkarua, the first definitive members of the phylum appeared near the start of the Cambrian period. The phylum contains about 7,000 living species, making it the second-largest grouping of deuterostomes, after the chordates. Echinoderms are also the largest phylum that has no freshwater or terrestrial representatives. The echinoderms are important both biologically and geologically: biologically because few other groupings are so abundant in the biotic desert of the deep sea, as well as the shallower oceans, and geologically as their ossified skeletons are major contributors to many limestone formations, and can provide valuable clues as to the geological environment. Further, it is held by some that the radiation of echinoderms was responsible for the Mesozoic revolution of marine life. Sand Dollar Temporal range: 56 –0 Ma The term sand dollar (or sea cookie or snapper biscuit in New Zealand, or pansy shell in South Africa) refers to species of extremely flattened, burrowing echinoids belonging to the order Clypeasteroida. Some species within the order, not quite as flat, are known as sea biscuits. Related animals include the sea urchins, sea cucumbers and starfish. Anatomy: Sand dollars, like all members of the order Clypeasteroida, possess a rigid skeleton known as a test. The test consists of calcium carbonate plates arranged in a fivefold radial pattern. In living individuals the test is covered by a skin of velvet-textured spines; these spines are in turn covered with very small hairs (cilia). Coordinated movements of the spines enable sand dollars to move across the seabed. The velvety spines of live sand dollars appear in a variety of colours—green, blue, violet, purple—depending on the species. The tests of dead individuals are often found on beaches, the textured skin missing and the skeleton bleached white by sunlight. The bodies of adult sand dollars, like those of other echinoids, display radial symmetry. The petal-like pattern in sand dollars consists of five paired rows of pores. The pores are perforations in the endoskeleton through which podia for gas exchange project from the body. The mouth of the sand dollar is located on the bottom of its body at the center of the petal-like pattern. Unlike other urchins, the bodies of sand dollars also display secondary front-to-back bilateral symmetry. The anus of sand dollars is located at the back rather than at the top as in most urchins, with many more bilateral features appearing in some species. These result from the adaptation of sand dollars, in the course of their evolution, from creatures that originally lived their lives on top of the seabed (epibenthos) to creatures that burrow beneath it (hyperbenthos). The Common Sand Dollar, Echinarachnius parma, is widespread in ocean waters of the Northern Hemisphere, from the intertidal zone to considerable depths. It can be found in temperate and tropical zones. The Keyhole Sand Dollar (three species, genus Mellita) is found on a wide range of coasts in and around the Caribbean Sea. Genus: Clypeus Kingdom: Animalia (Animals) Class: Echinoidea Order: Clypeaseroida Phylum: Echinodermata

Collection

Fossil Collection

Acquisition

Accession

78.57

Source or Donor

Delmar Smith Fossil Collection

Acquisition Method

Donation

Dimensions

Width

3-13/16 in

Depth

1-1/2 in

Length

3-13/16 in

Location

Location

Container

Left

Drawer

3rd Shelf

Shelf

Right

Cabinet

Case # 50

Wall

North

Room

Delmar Smith Hall

Building

Crater Rock Museum

Category

Permanent