Eat or Be Eaten --Predation may not be pretty, but that's nature.
Thursday, April 30, 1998
There is a "tooth and claw" aspect of nature that isn''t (by our reckoning) pretty. Witness the recent Herald article reporting on orca (killer whale) predation on migrating gray whale calves.
It is only natural that we would put ourselves in the place of the calf and wonder what it must be like to be pursued by a pack of hungry orcas and finally, eaten alive. Most of us would prefer almost any other way of being dispatched and some very successful movies have done well with this theme >(Jurassic Park and Jaws, to name the two I''ve seen). With a species as close to us as a whale is (we''re all mammals with fairly well-developed brains), it is likely accurate to assume that a whale calf must feel about as we would in the midst of an involuntary advance up the food chain. Frankly, I''d rather be in Philadelphia.
I like whale sharks. They are big (the largest of fishes at 50--and some think 70--feet long.) And they don''t eat big things. I''ve spent a couple of hours swimming with them and photographing them in the Sea of Cortez. It was a thrilling experience. They have tiny teeth and they somehow manage to filter copepods the size of rice grains from the plankton while swimming lazily around with their mouths open. A person would have to try hard to get eaten by a whale shark and you''d probably get spat out even if you managed to lunge past the lips.
A few years ago, three orcas killed and ate a small (20-foot) whale shark. My neighbors in Bahia de los Angeles took a video of the episode. It may have been one of the sharks I''d photographed the year before. Really sad. I''d grown fond of those sharks. The orcas were throwing 100-pound chunks of shark through the air. Orcas sometimes play with their food. They''re just big dolphins, and dolphins play a lot. Sometimes with their food. I suspect their parents reprimand them if it goes on too long.
All animals in nature are subject to the possibility of predation. Whales are born large, grow fast and are the largest animals ever to swim the ocean planet. Yet as we see during the gray whale migration, even a 20-foot long calf is not free of predation "pressure" from orcas. And adult whales are sometimes drowned by a pack of orcas.
It is difficult for us human not to attach motives and make value judgments about these natural events. Orcas are called "killer whales." Why? Hawks eat lizards, snakes, rodents, bunnies, salmon and other birds. Do we call them "killer birds?" Guppies eat each other. I have a tank full of "killer guppies" at home. They''re all just doing what evolution has sculpted them to be doing. They don''t think in terms of good or bad. Just hungry or satiated.
Humans have played the role of predator throughout most of our species'' history, and yet many of us have a problem with that role today. The animal rights movement would remove humans entirely from a role as predator. We let nature take its course and sea lion pups starve to death during an El Ni¤o year. But shooting sea lions to "cull the herd" is not acceptable. Some cultures consider whales and dolphins as seafood. Americans tend to find that approach repulsive. Very complex issues, these.
Let''s remember that the other predators are not attaching value judgments. Most animals in nature are either eaten alive or they die of starvation. That''s just the way it is. And will forever be.
Steven Webster is senior marine biologist at the Monterey Bay Aquarium.