Turtle-headed Sea Snake

The Turtle-headed Sea Snake is the odd one out among sea snakes. It eats nothing but fish eggs, and over evolutionary time it has largely given up the equipment that makes its relatives dangerous.

Its fangs are tiny, its venom glands are much reduced, and it is regarded as effectively harmless to people.

That is a fact about the species, not permission to handle sea snakes. The species that will hurt you and the species that will not are not reliably distinguishable in the water by anyone without training.

About the Turtle-headed Sea Snake

Adults reach around 75 centimetres to a metre, moderately built, with the usual laterally flattened body and paddle tail.

The pattern is bold and distinctive: broad, clean bands of black or dark brown alternating with cream, white or pale orange, running the whole length of the body.

The head gives the species its name — short, blunt and rounded, quite unlike the tapered head of other sea snakes. Males carry a small spine on the tip of the snout, used during courtship.

Habitat

Where can you find a Turtle-headed Sea Snake?

It is tied closely to coral reef, because its food is:

• coral reefs and reef flats
• shallow lagoons
• rubble and hard bottom adjoining reef
• areas with abundant damselfish and blenny nests

It occurs on Australian reefs including the Great Barrier Reef, and through the western Pacific. It is a shallow-water species and is rarely found far from live coral.

Venom

Is the Turtle-headed Sea Snake dangerous?

Not in practical terms. A diet of fish eggs requires no venom and no fangs worth speaking of, and this species has correspondingly reduced both — the fangs are minute and the venom apparatus is much diminished. It is regarded as effectively harmless to humans.

It should still never be handled, for two reasons. It is protected wildlife, and identifying sea snakes at close range is exactly the mistake that gets people bitten by the species that are dangerous.

If you cannot tell a Turtle-headed Sea Snake from a Dubois' Sea Snake underwater — and most people cannot — then the safe rule is the simple one: hands off, every time.

Diet

What does the Turtle-headed Sea Snake eat?

Fish eggs, and essentially nothing else:

• damselfish eggs
• blenny and goby eggs
• other demersal fish eggs laid on coral and rubble

It scrapes egg masses off coral and rock using its blunt snout and modified jaws. The whole animal — head shape, teeth, venom, behaviour — has been reshaped around that one food source.

Behaviour

What should you know about this species?

Turtle-headed Sea Snakes are diurnal and forage over shallow reef, surfacing regularly to breathe.

They are placid and slow-moving compared with other sea snakes, which reflects a diet that does not run away.

Interestingly, populations on reefs affected by pollution and human activity often become much darker or entirely black — a pigment change linked to shedding accumulated trace metals through the skin.

What to do if you see a Turtle-headed Sea Snake

Watch it and leave it alone. It is one of the more rewarding animals to observe on a reef and it needs nothing from you.

Do not handle it, even knowing what it is. It is protected wildlife, and close-range sea snake identification is not a habit worth developing.

If you find one stranded, treat it as you would any sea snake: do not touch it, and call us with the location.