Seafaring Mammals: Dolphins are toothed cetaceans, or marine mammals, and the killer whale is the largest of them. Dolphins have teeth, but they only use them to hold on to their prey, not to chew -- they swallow their dinner whole. Like all mammals, they need to stay warm, so they use a protective layer of blubber to insulate them in the water. Among the most intelligent animal species, dolphins communicate using echolocation and high-pitched clicks.
After the Spill: Because dolphins come up to the surface to breathe, they can inhale toxic oil fumes, which can cause long-term illness and even suffocation. Additionally, oil can irritate dolphins' mouths and eyes. As it contaminates the food supply, an oil spill can force dolphins closer to the shore. Between April 30 and July 4, 2010, 57 stranded dolphins were found in the Gulf, and only two of those survived.