Attachment to suspended particles may improve foraging and reduce predation risk for tintinnid ciliates

Abstract

We describe a new behavior of planktonic ciliates. The field-collected tintinnid Eutintinnus inquilinus attached with its lorica to a range of surfaces, including particulate aggregates. Most tintinnids remained attached with the aboral end of their lorica when well fed. On starvation, many tintinnids detached and resumed a free-swimming life. We hypothesize that the adhesive property of the lorica has evolved as an adaptation to attach to suspended aggregates or other seston particles. Attached E. inquilinus have a feeding rate that is 80% higher than freeswimming individuals because of the change in the fluid dynamics of the feeding current for attached E. inquilinus, which leads to steeper velocity gradients and higher flow rates close to the lorica. This mechanism will also operate for swimming suspension feeders attached to smaller particles that significantly increase the hydrodynamic drag. Selection for traits that enhance the velocity gradients in feeding currents of small plankton may be common and may partly shape behavioral patterns and functional morphology. When exposed to the calanoid copepod Acartia clausi, populations of E. inquilinus were less susceptible to predation than another Eutintinnus species of similar morphology but that were entirely free swimming.

Protistan Grazing on Marine Bacterioplankton

“…It has been calculated that the hydrodynamic flow field of attached suspension feeders makes possible higher feeding flow rates and thus higher clearance rates (Lighthill 1976). This has also been confirmed experimentally for HNF (Christensen-Dalsgaard and Fenchel 2003) and tintinnid ciliates (Jonsson et al 2004). Cultured flagellates tend to attach to surfaces (Boenigk and Arndt 2000;Fenchel 1986a), and a high potential for colonization of marine snow particles by HNF has been demonstrated (Kiørboe et al 2003).…”

Epibiotic ciliates Scyphidia sp. and diatoms on Tigriopus fulvus (Copepoda: Harpacticoida) exoskeleton

“…10,16,17 Some ciliates may attach and detach randomly without the intervention of specialized structures, 18 but others produce stalks that allow them to better adhere to the surfaces. 19 Copepods and cladocerans, being dominant in the zooplankton, are one of the main living supports providing attachment sites for a wide range of microorganisms that find abundant available binding surfaces on their exoskeleton.…”

Ciliate Epibionts Associated with Crustacean Zooplankton in German Lakes: Distribution, Motility, and Bacterivory

“…While some ciliates may attach and detach in a haphazard manner that requires no special adhesive mechanism (Jonsson et al, 2004), others use distinct and elaborate structures, such as the stalks in peritrich ciliate epibionts, to more firmly attach to surfaces (Randall and Hopkins, 1962). The production of stalks and the subsequent loss of these structures during detachment represent a considerable energy investment by the ciliates, and must be compensated by substantial benefits of attachment.…”