galleryWildlife Drowning in Oil05.03.10galleryWildlife Drowning in OilCrews are trying to keep much of the Gulf oil spill below the ocean's surface—where it threatens to harm a teeming dolphin population. Eli Kintisch on a menacing scientific mystery.05.03.10 4:57 PM ETGetty ImagesDolphinWhile there have been reports of dolphins being able to identify oil and mindfully avoid it, they are still apt to inhale oil and oil vapor when they surface to breathe, which leads to damaged airways. This time of year is birthing season for about 5,000 dolphins that frequent the Gulf Coast area. Consumption of oily prey can also transfer contaminants to younger dolphins via the mothers’ milk. Mark Ralston, AFP / Getty ImagesAlligatorThe alligator, already in danger of extinction, will likely see steep declines in fish and seabird populations it feeds on.Joe Raedle / Getty ImagesCrabCoastal habitats around the Mississippi River delta are vital for crab survival and reproduction, but are quickly becoming overrun by the oil, potentially devastating populations for years to come.Dave Martin / AP PhotoTernLeast terns, whose population has dropped to 2,000 from 12,000 in recent years, might find their entire population wiped out. In less than 40 days, tern chicks will be hatching and leaving the nest to explore what might be an oil-filled landscape.Joe Raedle / Getty ImagesFishWhile the floating oil is already the suspected cause of death for numerous fish washing ashore along the Gulf Coast, dispersants used by BP to break up the oil also have been reported to contaminate the water with toxins able to kill fish over vast distances.Alex Brandon / AP PhotoNorthern Gannet birdThe first avian casualty of the oil spill to be captured and treated was a northern gannet: a native, fish-eating, diving bird that could be affected not only by diving through the oil slick, but also by contaminated fish.Alex Brandon / AP PhotoMan-O-WarAn unusual number of jellyfish have washed ashore since the oil-rig explosion, and researchers are investigating whether the incidents are linked.Joe Raedle / Getty ImagesWhite IbisThe white ibis nesting area in the Delta National Wildlife Refuge is being threatened by the approaching oil slick. As a wading bird, the ibis also frequents shallow waters in search of food that may become contaminated.Chris Graythen / Getty ImagesOysterOyster beds in the Breton Sound along the eastern bank of the Mississippi River could be affected by the expanding spill, damaging an entire generation of the shellfish. Even if the spill is contained, however, oil residue may still be sucked through the oysters.Eric Gay / AP PhotoShrimpShrimp coming in to the Gulf region won’t find their usual prime spawning grounds—instead, the plankton they eat could be smothered by the oil.Joe Raedle / Getty ImagesTurtleAt least 30 sea turtles were found dead over the weekend, including some from the world’s most endangered species of turtles, the Kemp’s Ridley turtle, which is entering its primary nesting season along the Gulf.