Elapidae
Black-headed Sea Snake
Hydrophis atriceps
A dangerously venomous marine snake confirmed in Australian waters around Darwin.
Dangerously venomous.
Identification and appearance
The narrow front of the body is dark olive to black, interrupted by yellowish oval side markings that can extend across the back. The rear is greyer. Young snakes have more complete dark rings, which can break into side markings as they grow.
Other names
Banded Sea Snake
Typical length
AROD reports a species average of about 100 cm; an independently verified total maximum and typical adult interval were not established.
Head appearance
small head
Key identification features
- Small head and narrow front of body
- Yellowish side markings on a dark front
- Greyer rear; more complete rings in young
Where it is found
An Australian specimen is documented from around Darwin in the NT. Western Australian occurrence is questioned in the Reptile Database, so the wider range remains uncertain.
Diet
Feeds mainly on long, eel-like fish.
Reproduction
Live-bearing.
Medical significance
Treat any suspected snakebite as an emergency: call 000 and follow snakebite first aid. Do not wait for identification.
What to do if you encounter one
Keep clear and do not handle, net or disentangle a sea snake. Contact qualified wildlife help if a stranded animal or fishing-gear entanglement needs attention.
Taxonomy notes
The Reptile Database questions Western Australian occurrence; the confirmed Australian record retained here is around Darwin in the Northern Territory.
Sources checked
- Australian Reptile Online Database — Black-headed Sea Snake (2026-09-25)
- The Reptile Database — Hydrophis atriceps (2026-09-25)
- Rasmussen et al. 2014 — Sea snakes in Australian waters (2026-09-26)
- FAO — Hydrophis atriceps species account (2026-09-26)
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A profile is a guide, not a reason to approach or handle a snake.