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Radolarians are unicellular protozoa that form glass skeletons and live exclusively in the ocean. They absorb silica from ocean water to construct tiny glass skeletons 0.1 to 2 mm in diameter. Radiolarian skeletons tend to have arm-like extensions that increase surface area for buoyancy and assist in the capture of small prey. Radiolarians occur in large populations to comprise a significant part of the ocean's plankton. When they die, their hard skeletons sink and settle on the sea floor. Thick deposits of radiolarian skeletons make up sedimentary rock that formed over millions of years. Stones quarried for the Egyptian pyramids are largely made up of radiolarian and foraminiferan skeletons. Radiolarian fossils are known from the Cambrian period (540 million years ago).
Image and text copyright © Dennis Kunkel. All rights reserved. |
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