Anglerfish entered the midnight zone 55 million years ago and thrived by becoming sexual parasites

Anglerfish first colonized the ocean's midnight zone 55 million years ago, during a period of extreme global warming, a new study finds.

Many anglerfish species patrol the benthic, or seafloor, zone, ranging from the near shore to depths of thousands of feet.

Living in the midnight zone means having no real home — there are no reefs, caves, seaweed or other substrate to grasp onto.

This lifestyle is not conducive to finding a mate, but the researchers suggest anglerfish adopted new breeding strategies to thrive in this featureless landscape.

But the loss of these immune functions — the generation of certain antibodies for example —enables the female to accept the male as part of her own body, feeding him with her blood supply.

The researchers believe that the degeneration of the immune system and its facilitation of sexual parasitism were advantageous during this period of radical ecosystem upheaval, allowing anglerfish to head off into the featureless depths and diversify into the array of Lovecraftian creatures that stalk the midnight zone today.