| P number: | P550276 |
|---|---|
| Caption: | Hemicidaris intermedia, a fossil echinoid. |
| Description: | Hemicidaris first evolved in the early Jurassic, and ranged through to the mid-Cretaceous times (the Cenomanian, about 93-99 million years ago). Hemicidaris intermedia is a species that lived during the Jurassic. Hemicidaris intermedia has a medium-sized, almost spherical test. It is covered with many large tubercles, to which club-like spines were attached during life. The ambulacral plates have much smaller tubercles. It is a regular echinoid with the anus at the centre of the apex of the test and the mouth is in the centre of the underside. Gill notches occur round the mouth. Echinoids (sea urchins) have lived in marine habitats since the Ordovician times, about 450 million years ago. They still live today, inhabiting many shallow, near shore seas around the world. As fossil echinoids resemble living species, we have an idea how they must have lived. They had spines which are used for protection. Some species protected themselves from carnivores by having poison-tipped spines while others had large, unpalatable solid spines. Echinoids burrowed into the sand or crawled over the sea floor on their tubed feet, which extended from the paired pores on the star-like or petal-like areas (the ambulacra). They grazed and scavenging algae and plants or ate small particles in the sandy substrate. |
| Photographer: | Unknown |
| Copyright statement: | Unknown |
| Orientation: | Landscape |
| Size: | 474.03 KB; 1000 x 961 pixels; 85 x 81 mm (print at 300 DPI); 265 x 254 mm (screen at 96 DPI); |
| Average Rating: | Not yet rated |
| Categories: | Best of BGS Images/ Fossils |
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