Just off the coast of Pascagoula, Miss., the waters are still teeming with 10 species of sharks 15 days after an offshore rig blew up, killing 11 workers gushing oil out of an undersea well.
"We haven't had any indication that there's oil in this area," said Eric Hoffmayer, a marine biologist at the Gulf Coast Research Laboratory.
Marine biologists are rushing to establish a baseline sample of the shark population by documenting their size and overall health before the oil hits, CBS News Special Contributor Jeff Corwin reports. The oil is a threat to more than 600 animal species.
The biologists are especially worried because waters near Pascagoula are a fragile nursery for young sharks. This is a critical time for these sharks.
"We don't know what the implications are going to be with exposure to this oil, but in theory it could have a tremendous impact on the pups that are born this year and the populations that we have here in the north are critical to the Gulf of Mexico," Hoffmayer said.
Even if the oil doesn't get to the sharks, the sharks may get to the oil.
"These things could probably swim between 10, maybe 15, 20 miles a day," Hoffmayer said.
If a shark is capable of swimming 20 miles a day, it's capable of swimming where the slick is, so it could be in healthy waters one day and poison waters the next.
If sharks come in contact with oil, two things can happen. They can suffocate to death because they breathe water through their gills. Also, if the fish they hunt is contaminated by oil, they can be poisoned by eating the toxic chemicals in the crude.
Dolphins, on the other hand, are mammals and like human beings breathe air into their lungs to survive. If they come up to the surface of that water and there's oil floating on top, they can breathe in that oil into their lungs through their blow hole and can suffocate as well.
Also like the sharks, they're targeting fish that could be contaminated.
All species in the Gulf, either creatures living along the coastline like the birds or the animals in the water, are vulnerable to this very toxic oil spill.
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