Images Dated 21st September 2004

Coloured SEM of foraminiferan, Spirolina sp

Foraminiferan shell. Coloured scanning electron micrograph (SEM) of the test (shell) of the Mediterranean foraminiferan, Spirolina areitinus. Foraminifera are single-celled protozoa which construct and inhabit shells composed of several chambers. These are usually penetrated by pores through which the cellular contents is extruded. The organisms live in the sea or salt- water lakes. The shells form an important component of chalk. In previous geological ages foraminifera occurred in such large numbers that their shells, largely of calcium carbonate, have formed fossil deposits seen today as limestone. Magnification: x72 at 6x7cm size. x180 at 6.25x4.75ins

© POWER AND SYRED/SCIENCE PHOTO LIBRARY

Colemans shrimp on a sea urchin

Coleman's shrimp (Periclimenes colemani) on the body of a venomous sea urchin (Asthenosoma varium). This shrimp is found exclusively on this sea urchin, whose poison provides them both with protection from predators. The host urchin is not harmed by the shrimp, nor does it derive any benefit from carrying it. This type of relationship is called commensalism, a type of symbiosis. Photographed in Sulawesi, Indonesia

© GEORGETTE DOUWMA/SCIENCE PHOTO LIBRARY

Graceful pearlfish

Graceful pearlfish (Encheliophis gracilis) peering from the anus of the sea cucumber Bohadschia argus. The pearlfish is parasitic on the sea cucumber, living inside its gut and feeding on its internal tissues. In this way it hides itself from predators and ensures a permanent food supply. Photographed in Irian Jaya, Indonesia

© GEORGETTE DOUWMA/SCIENCE PHOTO LIBRARY