This Sea Snake Only Lives In One Place On Earth – And It's Not The Sea

The animal world is full of contradictions, from tiny mouse-deer that are neither mice nor deer, to vampire squid that aren’t vampires or squid. Now, we come to another confusingly named creature: the Garman’s sea snake is a snake, but it doesn’t live in the sea. 

Garman's sea snake (Hydrophis semperi) is one of only two species of sea snake that don't live in the sea, the other being Crocker's sea snake (Laticauda crockeri). Garman's sea snake does belong to the true sea snake family, called Elapidae, but with one key difference – it doesn't live in saltwater at all and instead inhabits the freshwater ecosystem of Taal Lake in the Philippines. 

Taal Lake is fascinating in its own right. Formed by the collapse of a volcanic chamber during an eruption in 1754, the resulting debris and ash blocked the way to the sea, and the rainwater that accumulated inside the area gradually turned the once saltwater into freshwater. The eruption also resulted in many species being trapped inside this water, which eventually led to the unusual sea snake we see today.

Taal Lake is also the only place on Earth where the Garman’s sea snake can be found. The IUCN lists the species as vulnerable, but notes that the lake "is part of an active volcano, and an area of high seismic activity. Eruption could destroy the entire habitat of this species." Other threats to the species include problems associated with tilapia fish farming, habitat loss, and damage to water quality via pollution from agriculture.

Garman's sea snake is a venomous species that feeds on creatures like gobies and eels, spending its time looking into crevices and holes for such prey. It can do this because, like other sea snakes in its genus, the species has a smaller head relative to the width of its body.

Despite its freshwater existence, Garman’s sea snake is part of a group of other fully aquatic reptiles and gives birth to live young in the water. These snakes are capable of holding their breath, but must return to the surface to breathe at regular intervals.