Some sea snakes can breathe through their skin

You might think that it's just fish that have gills, but there are several species of sea snake that breathe through their skin as well. For example, the Hydrophis cyanocinctus has been found to breathe through the top of its own head. It has a small hole and collection of blood vessels at the top of its head for picking up oxygen from the seawater and sending it to the reptile's brain while it moves underwater.