Benthic behavior of planktic foraminifera

Abstract

In culture containers with sediment on the bottom, two of six species of planktic foraminifera reveal characteristic benthic activities, such as reorientation, crawling, and burrowing. Globigerinella siphonifera creates well-organized burrows and excavated sediment on a circular pile. Globorotalia menardii and Globigerinella siphonifera have specific crawling and burrowing orientations, with crawling speeds of up to 1 mm/min and burrowing speeds of 0.5–2 mm/hr. Globigerinoides ruber, Globigerinoides sacculifer, Hastigerina pelagica, and Orbulina universa did not exhibit any benthic activity and died on sediment substrates. The ability to live in a benthic mode may be a strategy in species adapted to the deep chlorophyll maximum, or neritic environments, where they exploit floating organic aggregates (marine snow) as a pseudobenthic habitat and a source of food. Benthic and pseudobenthic behavior may have been widespread in Mesozoic planktic foraminifera and may explain their widespread occurrence in epicontinental seas.