Predation on forandnifera by the dentaliid deep-sea scaphopod Fissidentalium megathyris

The dentaliid scaphopod Fissidentalium megathyris, collected from Pacific deep-sea sites off central California, was dissected and examined for prey items. Gut contents revealed that it takes almost exclusively benthic foraminifera, thus indicating that foraminiferal cytoplasm is an important component in the diet. Individual scaphopods contained up to 188 and averaged 33 foraminiferal specimens. On average 73.6% of ingested foraminifera tests had mechanical and/or chemical test damage. Mechanical damage was inflicted chiefly on the last three or so chambers. The mechanical manipulation of the tests by the radula alone could result in damage to the last chambers. Test destruction may result from selective chamber destruction, weaker construction of the last chambers than of the rest of the test, mechanically more vulnerable last chambers, or a combination of all three of these. The high number of ingested tests indicates that deep-sea scaphopods may exert significant predation pressure on benthic foraminifera, which may also lead to preferential destruction during taphonomic and diagenetic processes.