The amphibious fish that mates with itself
Species: Kryptolebias marmoratus
Habitat: Mangrove swamps on the east coast of North and South America
Faced with the inevitability of death, some people draw up a "bucket list": a checklist of things they plan to do, like learning a musical instrument or visiting the Grand Canyon. The Bucketlist website collates these ideas, including such gems as "play chicken with a train and lose". Yet nowhere on the site has anyone expressed a desire to have sex with themselves while living in a tree.
This shows a deplorable lack of initiative, because it wouldn’t even be a world first. The mangrove killifish is way ahead of us. It lives in pools that are prone to drying up, so it can also live on land for months at a time – often inside hollowed-out logs – where it survives by breathing through its skin. It’s also one of only two vertebrates – the other being the closely-related ocellated rivulus – that can self-fertilise.
These abilities give rise to a peculiar society made up of groups of clones that compete with each other for survival.
Send in the clones (Image: Jean-Paul Ciceron)