Dense dwarfs versus gelatinous giants

Thursday 13 Jun 19
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Thomas Kiørboe
Professor
DTU Aqua
+45 35 88 34 01

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Anders Peter Andersen
Associate Professor
DTU Physics
+45 45 25 33 12

A new theoretical model describes the trade-offs and physiological limits determining the body plan of planktonic filter feeders and explains why gelatinous plankton are gelatinous.

Gelatinous plankton form a special group of marine organisms due to their distinctly watery bodies with low carbon content. We find the gelatinous body plan mainly in large, centimeter-sized plankton. Some gelatinous plankton feed by filtering their micron-sized prey out of the water instead of perceiving it at a distance. Why do such planktonic giants tend to be gelatinous while microbes (dwarfs) that filter feed on the same prey stay dense?

By modelling the energy budget of filter feeders, we show that the interplay between gain and cost of energy results in the key implication that a minimum filter area is necessary to collect enough food to sustain a living. Through comparison of the model predictions and existing data on filter feeders, we conclude that filter feeders need to be either small or, if they are large, they need to increase the filter area by being gelatinous to survive in dilute oceanic environments. Large plankton that are non-gelatinous also exist, but they either live in prey-rich environments or compensate by sensing their prey at a distance. Such understanding of planktonic survival strategies is essential to model and predict the global distributions of plankton.

Contact: Julia Dölger, Postdoctoral Associate, Massachusetts Institute of Technology, jdoelger@mit.edu 

Read the paper here: Julia Dölger, Thomas Kiørboe, and Anders Andersen, Dense Dwarfs versus Gelatinous Giants: The Trade-Offs and Physiological Limits Determining the Body Plan of Planktonic Filter Feeders, The American Naturalist (2019).

Image credits: Lasse Tor Nielsen and Kelly R. Sutherland
https://www.mecano-plankton.dk/news/Nyhed?id=%7B8C288AF5-FA38-47A5-9C4F-A23CA488C0A0%7D
9 DECEMBER 2019