For millennia, people have wondered just how many species live on Earth. The latest study looking to answer this question suggests there are about 8.7 million species, the majority of which scientists can’t even name.
The oceans, as almost three-quarters of the Earth’s surface, are home to millions of species—and only about 1 in 10 has been officially discovered by scientists. Here are ten ocean-dwellers we think are especially fascinating:
1. The box jellyfish, which lives in the waters off North Australia and Indonesia, is one of the most venomous species in the ocean. Its 10-foot-long tentacles can kill even cautious swimmers, yet some kinds of sea turtles can eat box jellyfish without even an upset stomach.
2. The lovely hatchetfish might be redefining lovely, but its thinness when viewed head-on helps it hide from predators, as does its silver color and bioluminescence.
3. Sailor’s eyeball is the oceanic equivalent of skinless grapes at Halloween. This seaweed lives in waters around the equator, where it reproduces by disintegrating once young plants have formed inside of it.
4. The blue-ringed octopus may look pretty, but its vivid colors, which become brighter when the animal is disturbed, mark it as extremely poisonous—it is the most dangerous cephalopod and its saliva can kill a human.
5. The stonefish, the most venomous fish, can also kill a human with one sting. It takes its name from the camouflage that allows it to lie in wait for passing fish.