1 of 11 Threat of extinction Photo: By Gl0ck/Shutterstock We know by now that the Deepwater Horizon oil spill has been disastrous for the entire Gulf ecosystem, and that at least 600 Gulf species are likely to experience reduced numbers and harmful effects for generations to come. For a handful of species, however, the spill may be the final nail in the coffin. The situation is so dire that one major online gambling site has begun allowing bets on which Gulf animals are most likely to be declared extinct first. Here's our list of the 10 Gulf animals that are beyond threatened — they are at risk of extinction.

2 of 11 Kemp's ridley turtle qnr /Flickr. All sea turtles species in the Gulf are at risk of possible extinction, but none are as threatened as the Kemp's ridley. This species is the smallest and the rarest sea turtle in the world. Considered critically endangered and at risk of extinction before the oil spill, the Kemp's ridley could become the first animal to disappear entirely thanks to BP. The situation has prompted the U.S. Fish and Wildlife Service to attempt the largest and riskiest sea turtle egg relocation ever attempted. About 70,000 eggs from all the Gulf's species have been moved to safer nesting grounds outside of the spill's influence.

3 of 11 North Atlantic bluefin tuna Photo: By Guido Montaldo/Shutterstock Critically endangered and overfished, North Atlantic bluefin tuna numbers have plummeted by 90 percent since the 1970s. Now the oil spill has the potential to erase the entire U.S. population because most of the fish use the Gulf of Mexico as their spawning ground. Even worse, they typically arrive in the Gulf to spawn between April and July, coinciding perfectly with the oil spill. Adult tuna are additionally threatened by the large underwater oil plumes which occupy the same ocean layers where the fish typically travel.

4 of 11 Great Lakes piping plover Steven Senne/AP. Only 71 breeding pairs remain of this critically endangered population of shorebirds. The birds typically spend the winter along the Gulf Coast. Tiny and adorable, piping plovers forage for food around the high tide wrack zone along the waters edge, making them especially vulnerable to the oil spill as it coats the coastline. Other endangered populations of the piping plover, which can be found along the East Coast and in the Midwest, are similarly threatened.

5 of 11 Elkhorn coral Scubaben /Flickr. The amount of Elkhorn coral in U.S. waters is already dangerously low. It is one of the most important reef-building corals in the Caribbean and Gulf. The species spawns each year within a few days of the August full moon, and in a normal year only 1 percent of those spawn survive their first few weeks of life. If exposed to oil, the entire year's spawn could potentially be wiped out.

6 of 11 Brown pelican Charlie Riedel/AP. Perhaps no species has received as much press coverage as the brown pelican during the oil spill cleanup. Removed from the Endangered Species List just months before the oil spill, the brown pelican may soon be added back to the list. Crude oil is particularly dangerous to birds because it coats their feathers, making it impossible for them to fly away. The oil interferes with the pelican's ability to regulate body temperature, and it forces the bird to consume copious amounts of the oil as it tries to preen its plumage.

7 of 11 Sawfish Photo: By Bonnie Taylor Barry/Shutterstock Once widespread in U.S. waters, this fish with the toothy, saw-like snout has been an icon for some Gulf communities. Now the stuffed sawfish that hang in some backcountry saloons and fisherman's pubs may become a reminder of the past. Two species of sawfish that inhabit the Gulf, the smalltooth and largetooth, are greatly threatened by encroaching oil. The largetooth sawfish may already be extinct in the region, and many of the smalltooth populations have nurseries that are confined to a region now threatened by the oil spill.

8 of 11 Sperm whales Photo: By Shane Gross/Shutterstock Although sperm whales occupy most of the world's oceans, the population that resides in the Gulf is particularly vulnerable. Dead sperm whales coated in oil have been found floating or washing ashore along the Gulf Coast. In addition, miles-long underwater oil plumes threaten the deep waters where these animals feed. If the Gulf oil spill kills a mere three individuals, the entire population could crash, according to a 2009 stock assessment report by the National Oceanic and Atmospheric Administration.

9 of 11 Manatees psyberartist /Flickr. Before the oil spill, the Florida manatee population had already experienced a 12.5 percent drop in population because of this year's unseasonably cold winter. Much of what remains of the fragile population may be swimming directly into the oil spill as the beasts migrate to their summer waters along the Gulf Coast. If the oil slick impacts the manatees' home off the coast of Florida, that could trigger a massive, never-done-before rescue effort and may imperil the species' odds of returning to their natural habitat.

10 of 11 Gulf sturgeon U.S. Fish and Wildlife Service. The Gulf sturgeon is just one of hundreds of fish species threatened by the oil spill. Already considered a species at risk, the oil slick could potentially cover what remains of this animal's remaining habitat. Even worse, sturgeon are currently preparing for their seasonal migration upstream to spawn. As oil reaches their congregation areas, the population could crash en masse.