Second Paper – Krill Benthic Feeding, Individual Movement with Aggregation Density, Stuff

Schematic of krill benthic feeding behaviors. Individuals can (A) “skim” the seabed to collect food; (B) “nose dive” into the sediment and tail-flick backwards to stir up sediment; or (C) “flip” onto their sides and “flop” around on the seabed by undulating their body several times to produce a plume of sediment. (D) Aggregations of krill can work together in a “ball” to stir up sediment into the water column. Individual krill move towards the center of the “ball” at the seabed (right), then upward to feed on the suspended sediment; krill then move towards the outside of the “ball” (left) before moving back down towards the seabed.

My second paper was published in March 2021 in Current Biology. This paper, titled “Lowered cameras reveal hidden behaviors of Antarctic krill”, talks about a number of things. The main points of this paper are (1) krill use a variety of different behaviors to feed from the benthos, including working together in giant balls; (2) krill are often found solitary or in very low density aggregations; and (3) krill move more quickly when in dense aggregations than solitary.

In general, it has been known for decades that individual krill are capable of feeding on the sediment. However, krill working collectively together to stir up the benthos has not been documented before. Also, this cooperative feeding behavior is incredibly rare for invertebrates. Nevertheless, we observed krill “ball-feeding” a number of times in late autumn. It’s likely that this behavior occurs when krill need to eat, and the only food available to them is carbon in the sediment.

Additionally, the idea of individual krill movement behaviors changing with aggregation density adds to the growing body of literature and observations about organisms in groups. It is also one of the few papers which addresses how the aggregations influence individual behaviors rather than how individuals can influence aggregations.

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