ALT: a picture of a whale in the ocean with the words bbc america rica on the bottom

Despite the filthy waters they often reside in, saltwater crocodiles don’t get sick that often. Perhaps we could one day harness the special proteins that help them.

ALT: a shark 's fin is visible in a national geographic advertisement

ALT: a killer whale is swimming in the ocean

ALT: whales are swimming in the ocean with a national geographic logo

Alt: a group of children are sitting at a table with the number 900 written on it .

ALT: a man is standing in front of a chalkboard with math equations on it .

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