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Uploaded on:
17/03/2009 09:55:07
Digital Asset
File Size:
369.18 KB
1000 x 760 pixels
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P number: P549494
Caption: Silurian fish.
Description: During Silurian times, about 420-430 million years ago, there were many different types of fish. They did not have bones in their bodies (just cartilage), but they had bony head shields and scales. Some were jawless and the distant relatives of modern lampreys and hagfish. They had a gaping mouth, like Loganella (bottom) and Jamoytius (middle). Other types of fish, like the 'spiny shark' Climatius (top) had a jaw. Loganella had a flat head with its mouth towards the underside and it is thought that it probably fed on small particles on the sea bed. Jamoytius had a narrow, tube-like shape, long fins along its back and sides and a powerful, down-turned tail. It had a sucker-like mouth and may have sucked the blood of other fish. Climatius had many spines running along its body, and two large dorsal fins, each supported by a bony spine. It used its large eyes to search out prey. Fish are cold-blooded vertebrates with a braincase, fins for swimming and gills to take oxygen from the water (although some also have lungs). They therefore differ from other aquatic creatures like invertebrate molluscs or crabs; amphibians and reptiles, which have lungs and limbs rather than gills and fins; and whales and dolphins which are warm-blooded mammals. Fish are the first vertebrates, having evolved during the early Cambrian over 500 million years ago.
Photographer: Unknown
Copyright statement: NERC
Orientation: Landscape
Size: 369.18 KB; 1000 x 760 pixels; 85 x 64 mm (print at 300 DPI); 265 x 201 mm (screen at 96 DPI);
Average Rating: Not yet rated
Categories: Best of BGS Images/ Artworks  


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