Sunday, April 29, 2012

Ephemeral Swarms of Zooplankton

Precise description is a fundamental requirement for doing science. This can lead to mind-numbing noun phrases such as “7-transmembrane domain G-protein-coupled receptor,” but also to “quorum sensing bacteria” and “Pleistocene megafauna.” The former is intriguing, the latter is totally awesome. (Imagine a ground sloth the size of a rhino eating palm nuts like they were Pez.)

This week I came across another precise, yet evocative, bit of descriptive biology: ephemeral swarms of zooplankton. Think of an ocean acre teeming with plankton, surrounded by miles of empty water. Sounds like a tasty morsel if you’re a baleen whale. Pump the flukes a few times to achieve dining velocity, open the jaws, and swim right through dinner. (Sort of like spraying Reddi-Wip directly into your mouth . . . )

The problem is that these nutritious plankton Woodstocks are few and far between, and they materialize unpredictably. So what’s a hungry humpback to do?

Julie Hagelin has been giving the question some thought and that’s why she was conjuring up Ephemeral Swarms of Zooplankton this past Friday at the AChemS conference. She drew an analogy with tubenose seabirds such as storm petrels, which use the scent of dimethyl sulfide (DMS) to locate areas rich in the tiny planktonic crustaceans on which they prey. What if a baleen whale sampled the air when it breeched, and headed upwind if it smelled DMS?

Hagelin suggests that this is exactly what they do. She and her colleagues presented data showing that humpback whales orient into the wind, which leaves them “well positioned to perceive volatile chemical stimuli.” In addition, baleen whales that specialize on zooplankton “have more notable olfactory systems than toothed whales.”

Hagelin et al. plan experimental tests of DMS to confirm their hypothesis. Talk about eating habits of your megafauna. This could be interesting.

The abstract discussed here, “Baleen whales and tubenose seabirds—A colossal chemosensory convergence?” by Julie C. Hagelin, Janice M. Straley, Lindsey B. Nielson, and Andy Szabo, was presented at the Association for Chemoreception Sciences annual meeting in Huntington Beach, California on April 27, 2012. The abstract can be found here.

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