Yesterday, my awesome housemate/landlady Wendy took me to work with her at the National Aquarium in Baltimore, where she generously supplied me with a desk for the day. I was lucky to be visiting on shark feeding day, which happens once per week, and Wendy invited me to come with her when she talked to the public about the shark feeding.
Shark feeding is much more interesting and complicated than I ever imagined! The sharks are located in a tank shaped like a giant “o”, with a large space in the center where the public stands. Above the tank (about 6″ from the surface of the water), and invisible to the public, is the shark catwalk, a skinny platform where aquarium staff stand as they feed the sharks. First, gates were dropped down in various parts of the “o”, dividing up the different shark species (apparently this part takes some serious effort and strategy on the part of whoever is dropping the gates) into 3 or 4 different groups.
Next, the sawfish (my favorite), were fed. Sawfish look like sharks, but they have long snouts that resemble chainsaws. Each side of their snouts has a line of sharp, pointy scales modified to look like teeth. The “teeth”, if completely broken off, never grow back. They use their dangerous snouts by waving them back and forth while swimming through schools of fish, injuring their prey. Then, they swim over the injured fish, gobbling them up with their stingray-like mouths.
Apparently The Aquarium’s sawfish are picky eaters, because I watched as a dead fish impaled onto the end of a stick chased around an uninterested sawfish. The whole scene was reminiscent of my childhood – watching a fork come toward my mouth as I heard one of my parents say “here comes the airplane….” Wendy tells me that the sawfish are very picky (spoiled!) about the fish species that they eat. Therefore, the aquarium staff often hides a more nutritious species of fish inside a tastier fish, to make sure that the sawfish get all of the nutrients that they need.
I asked Wendy where the fish that the sharks are fed come from, and got an unexpected answer. Apparently, every week, one of the shark staff goes to the local fish market, where he hand-picks fish for each shark. Every shark has a number, and each fish is prepared (with vitamins added, etc) exactly for that individual. When a shark eats a fish, both the shark and the fish that he ate are meticulously recorded.
I was surprised to notice how poor the aim of a hungry shark can be. I watched as sand tiger sharks ferociously snapped at fish on poles, and missed several times before they caught the fish. According to Wendy, they close their eyes when they get ready to eat, and rely on their other senses for aim. At the aquarium, the prongs holding the fish carry a slight electric current, which the sharks can sense and use to aim for their “prey”.