There's a reason marine biologists don't like to talk about it: Sex is one aspect of a shark's life that cannot be sugarcoated.

These terrors of the deep have vicious and brutal sex lives that pale in comparison to most mammalian sexual behaviors. The scientific truth of shark sex is not pretty and even harder to stomach — yet oddly fascinating.

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In honor of Shark Week, brush up on the strangely dark sexual side of these finned creatures. We dug deep into shark expert Juliet Epstein's book Demon Fish to find out the truth behind these amazing creature's sex lives.

As if you needed more reasons to find sharks scary.