Sometimes, there are some things in the natural world that baffle most of us (like the discovery of a desert pupfish for example), scientists included. Such a thing has been discovered recently: fish that can live in trees for months on end.

Meet the mangrove killifish (Rivulus marmoratus Poey). It's a 75mm fish that is highly... uhm, weird. It doesn't require a mate to procreate as it is hermaphroditic, and currently, mangrove killifish are the only known vertebrates with that particular quality.

Biologists have discovered another thing that sets the mangrove killifish apart from others, they can survive in trees when pools of water where they normally live dry up.

Brevard County Environmentally Endangered Lands Programme's Dr. Scott Taylor told New Scientist that the mangrove killifish "really don't meet standard behavioural criteria for fish." The fish move into rotting branches or tree trunks when water dries up - lining up neatly along grooves carved into the wood by insects.

The fish change their bodies to adapt to living above water, and they also curb their naturally territorial instincts when living end to end inside trees. When the mangrove killifish go back to the water, they revert back to their usual selves.