Sea snake discovered to have strange ability to breathe through its head

4 Sep 2019

Image: © Richard Carey/

The blue-banded sea snake has been found to have a rather unique way of breathing when descending into the murky deep.

The idea that a sea creature might breathe through its head might not sound so strange at first, given that fish have gills. However, an international team of researchers has found that the blue-banded sea snake (Hydrophis cyanocinctus) breathes rather differently to many other marine species.

In a paper published to the Royal Society Open Science journal, the researchers discovered that the creature breathes through its head using a complex system of blood vessels that draw in oxygen when swimming.

“For the first time, we describe this modified cephalic vascular network (MCVN) that provides this sea snake with a complementary supply of oxygen to the brain during submersion,” said lead researcher Dr Alessandro Palci, of Flinders University, Australia, who is also a visiting researcher at the University of Alberta, Canada.

“Basically we found that this sea snake uses the top of its head as a gill to breathe underwater.”

Images of the blue-banded sea snake head on the left and microCT scans of the head on the right.

Left: Two different angles of the blue-banded sea snake head. Right: MicroCT scans of the sea snake showing its modified cephalic vascular network. Image: Dr Alessandro Palci/Flinders University

Stay underwater for a long time

The sea snake is highly venomous and is known to live in the tropical waters of south-east Asia around coral reefs and warm coastal waters. Sea snakes must surface regularly to breathe but are among the most completely aquatic of all air-breathing vertebrates.

The recently discovered vascular network in the blue-banded sea snake is located just under the skin of its snout and forehead, surprising the team.

“While the MCVN is structurally very different from the gills of fish and amphibians, its function is nonetheless quite similar, in that it provides a large surface area packed with oxygen-depleted blood vessels that can efficiently take in oxygen from the surrounding water,” Palci added.

Dr Kate Sanders from the University of Adelaide School of Biological Sciences said that sea snakes have been extremely successful at adapting to a fully marine lifestyle.

“This feature probably allows these sea snakes to stay submerged for longer periods of time, which further research can test,” she said.

Colm Gorey was a senior journalist with Silicon Republic