Images Dated 25th October 1990

LM of the diatom Pinnularia nobilis

Light micrograph of the diatom Pinnularia nobilis (centre), surrounded by other assorted diatoms. The diatoms are a distinctive group of single- celled algae containing about 10, 000 species. They form an important part of the plankton at the base of the marine and freshwater food chains. The characteristic feature of diatoms is their intricately patterned, glass-like cell wall, or frustule. The frustule consists of 2 halves which fit together like the lid & bottom of a box. It is often decorated with rows of tiny holes, known as striae, which are arranged either radially or on the 2 sides of a central axis. Magnification: x400 at 35mm size

© POWER AND SYRED/SCIENCE PHOTO LIBRARY