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See Inside August 2011

Mouth Wide Open: The Challenge of Studying Deep-Sea Creatures

An aquatic scientist describes the challenges of studying creatures that live deep under the sea



Edith Widder Ocean Research & Conservation Association, Inc.

Name: Christopher P. Kenaley
Title: Postdoctoral research associate, University of Washington
Location: Seattle

I work on deepwater fishes—species that live anywhere below 200 to 3,000 meters deep in the ocean. The ones that I study, loosejaw dragonfishes, dwell about a kilometer down, in an area called the midwater zone. They have no skin between the two bones that form their lower jaw. This is unique to vertebrates. You might look at this animal and think, “How on earth could it possibly consume anything?” Say you had a natural history museum specimen in your hand, and you put a little tiny food fish in its mouth. You would watch it fall right out.

The deep sea is the largest ecosystem on earth, but we know very little about it. Dragonfishes are the dominant predators of this ecosystem, and they have features similar to those of most predatory fishes in the deep sea: they have long jaws and huge fangs. We hope to learn how predators of the earth’s largest ecosystem feed.
The interesting question is, Why have this loosejaw morphology?

I’m working on how these jaws perform using computer models. In January I’ll begin a postdoctoral research fellowship at Harvard, where I’ll be transitioning from the theoretical to building robots of these jaws. We’ll start with micro CT data from museum specimens. The micro CT machine hits the specimen with radiation, taking x-ray images in very thin slices—smaller than the micron level—that software can stack into a 3-D computer model. We’ll send that model to a 3-D printer that works much like the software does, printing thin slices of composite material to make a plastic model of the fish’s skull. We can then add material that will act as muscles, skin and tendons.

We could study dragonfishes in a lab if we could reproduce the conditions in which these fishes live: the pressure, the temperature and the low light. But to maintain these conditions in a lab is very, very difficult.

Perhaps the most challenging proposition to an animal living in the deep sea is the scarcity of available food. I hope this work will uncover how predators cope with scarcity and what physical features and behaviors are important in capturing prey in this barren seascape.

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