Trophic activity of planktonic foraminifera

Abstract

Few studies have been reported on the predatory habits of planktonic foraminifera or on their position in marine food webs. Planktonic foraminifera are large marine Sarcodina possessing a calcium carbonate shell (usually < 1 mm diam.) surrounded by a dense halo of rhizopodia that in some species may increase the cell diameter to 20 mm. Food organisms are snared by the sticky rhizopodia which entangle the prey and draw it into a dense layer of cytoplasm near the shell where digestion occurs (Anderson & Bé, 1976). Clearly species survival, their abundance, and their distribution in a region are deter-mined by the availability of food organisms, so that species that prey on a wide variety of organisms have greater survival advantage than those with a more restricted range of prey. Hence, many of the traditionally studied topics in foraminiferal research such as species abundance, survival time, geographical distribution and contribution to calcium carbonate sediments may be significantly determined by foraminiferal trophic activity. A clearer understanding of foraminiferal predation may help to explain ancient and modern assemblages of species and thus contribute to a more systematic interpretation of foraminiferal ecology.