Dr. Costello, Biologist
They are creatures so simple that scientists once considered them plants. But they're the critical group to study, if you want to understand motion and behavior. -- Jack Costello
Biologist John (Jack) Costello of Providence College has spent years studying jellyfish. He's found that despite the fact the jellies move almost constantly, they really don't seem to go anywhere. The jellies expend enormous amounts of energy simply pulsing. "That leaves us asking, 'Why would they spend their time swimming?'" Is it to swim, or to eat? Costello also wondered why the creatures possess a shape so seemingly inefficient for swimming. "That round disk shape is probably one of the least effective shapes for forward progress that we can imagine."
Then it occurred to him—perhaps there's more to the pulsing than pure propulsion. Adding tiny, neutrally buoyant beads into a tank of juvenile jellies, Costello tracked and videotaped the pattern of water flow around the pulsing animals. Lo and behold, he discovered that the flow created by swimming actually drew all the beads directly into the capture surfaces and mouth! "That body we think of as being bad or ineffective for forward motion is, in fact, very effective for creating the flow which enables the animal to feed."
About Jack Costello’s Career
John H. (Jack) Costello, Ph.D., is a professor of marine biology at Providence College in Rhode Island where he has been teaching since 1989. He received his Ph.D. in marine biology from the University of Southern California. Costello’s research interests include biomechanics; hydrodynamics and foraging of gelatinous predators; small-scale physical-biological interactions of zooplankton; and feeding and predator avoidance of zooplankton, in particular copepods.
Costello has collaborated on research projects to understand the relationships between form and function in medusae and to understand how this has influenced the evolution of jellyfish. His recent research has focused on how a gelatinous predator—a ctenophore— has shifted its distribution more in response to climate warming over the past 50 years than that of its major prey species, a copepod.
How did you choose your present profession?
Always, since I was a kid, I have loved swimming at the beach. So I hated arriving at the beach on a sunny morning when the seas were calm - perfect for swimming - only to find that jellyfish were teeming everywhere in the water. I dreaded swimming face-first into one. Or getting stung by them. Sometimes they were there, sometimes not. Why?
In college, I did an independent study on the causes of swarming by jellyfish. Later, after I had decided that I wanted to study marine biology, I had to choose a topic to study. Initially, I thought of studying what seemed to everyone else to be important issues: phytoplankton nutrient use, zooplankton growth, distributions etc. But then I decided that I needed to do something that would interest me particularly - not just what seemed important to other scientists. At that time, medusae weren't often studied nor were they considered too important. Fortunately, that's changed.
What would you recommend for students wanting to pursue a similar career?
Invest in yourself. Not necessarily financially. Find out what really interests you, what you can imagine yourself being fascinated in over the long term. What does it for you and challenges you? We're lucky in this country; we can pursue what interests us. Then do what it requires to follow your imagination. Sometimes it will be more education; sometimes it will be just doing exactly what interests you even if it seems alien to those around you - including your family and friends.
What do you like best about your profession?
Everything. I work outside in the environment; I work on challenging quantitative problems; I get to work with good people who are fun and value nature the way I do. I even get to teach students that want to find out about the most important world - the natural world. There is much more to know than I can ever learn; brilliant people - much more so than I can ever hope to be - have done work which I admire and hope to come close to emulating. These set goals that are almost impossible to reach. Almost. But not completely - I may be just able to reach them if I work well and am lucky. This is a great profession - I couldn't have wanted anything more - its already more than I ever imagined.
What web sites and references would you recommend for viewers interested in your work that was featured in The Shape of Life series?
None. Go outside. Forget virtual reality -- it's a poor substitute for real nature. Get away from the computer screen and get some nature next to your skin. As some scientists have said, "Study nature not books.”