Sneaky Animal Sex—Are They or Aren’t They?

From corals to cichlids, some animals have sex you never even see.

Animal sex is dizzyingly varied, and some mating methods make us wonder if we’d be able to tell whether we’re looking at a love scene, a fight, or just a friendly “Hello!”

Check out these animals. Would you be able to tell what they were up to if you caught them in the act?

Terri Ducay photographed these millipedes in central Thailand and wondered, “[Are they] trying to kill each other or making love?”

While the gonopods are on the seventh segment, the millipede’s sperm actually originates on the second segment. To transfer the sperm from the second to the seventh segment, the male bends his body so that his gonopods touch the openings where the sperm comes out, in effect “charging” them

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