Meet Hydrophis cyanocinctus, a snake that can breathe through the top of its own head. The three meter (9.8ft) species, which is native to Australian and Asian coastal waters, ...

The re-elaboration of Hydrophis cyanocinctus' visual function was in response to its bright underwater environment—which differed from the low-light habitats of some of its ancestors.

The re-elaboration of Hydrophis cyanocinctus’ visual function was in response to its bright underwater environment – which differed from the low-light habitats of some of its ancestors.

Hydrophis cyanocinctus is the only sea snake species known to breathe through the top of its head, using a special arrangement of blood vessels in much the same way as fish gills.

One of these is the venomous, blue-banded sea snake (Hydrophis cyanocinctus), ... they found that H. cyanocinctus snakes have evolved to bring back four copies of this ancestral SWS1 gene.

During submersion, the blue-banded sea snake (Hydrophis cyanocinctus) is now thought to use an extensive vascular network across the top of its head to absorb oxygen from the surrounding water.

The re-elaboration of Hydrophis cyanocinctus' visual function was in response to its bright underwater environment—which differed from the low-light habitats of some of its ancestors.