Elapidae

Mosaic Sea Snake

Aipysurus mosaicus

Mosaic Sea Snake is a northern Australian marine snake with irregular staggered cross-bands, recorded from offshore waters, estuaries and tidal rivers.

Venomous

Identification and appearance

The species description records a dark-brown head, a cream, salmon or yellowish body with brown to olive-green irregular cross-bands, often incomplete or staggered. Species-level separation from Aipysurus eydouxii uses specialist characters and should not be attempted by handling a sea snake.

Other names

Mosaic Seasnake

Typical length

The largest specimens in the revision were a male measuring 68 cm snout-to-vent plus a 14 cm tail, and a female measuring 95 cm snout-to-vent plus a 15 cm tail. These are observed specimens, not a typical adult size range.

Key identification features

Cream, salmon or yellowish body
Irregular brown to olive-green cross-bands
Marine, estuarine and tidal-river occurrence

Where it is found

Northern Australian coasts, including Coburg Peninsula, the Gulf of Carpentaria, Thursday Island, Townsville, Swain Reefs and Shoal Water Bay; also recorded from southern New Guinea.

Activity

Records are mainly from 2–22 m, with no checked records deeper than 50 m; females were reported gravid from May to August in northern Australia.

Diet

Benthic fish eggs.

Reproduction

Live-bearing.

Medical significance

Treat any suspected bite as an emergency. Call 000 and follow Australian snakebite first aid; do not wait for identification.

What to do if you encounter one

Keep well clear in water or on shore. Do not catch, touch or approach for a closer photograph.

Similar-looking snakes

Formerly treated as an allopatric population of Aipysurus eydouxii. The published distinction uses scale, band-count, internal-anatomy and skeletal characters, not a safe casual field check.

Taxonomy notes

Described as a species distinct from Aipysurus eydouxii in 2012; the revision notes that additional sampling is needed around New Guinea.

Sources checked

Sanders et al. 2012, Zootaxa — Aipysurus mosaicus revision (2026-09-26)
Sanders et al. 2012 — open article PDF (2026-09-26)
AROD — Mosaic sea snake (2026-09-26)
ANZCOR — Australian snake bite first aid (2026-09-26)

For any suspected snakebite, call 000 and follow snakebite first aid.

Snake bite first aid

Call 000 for an ambulance for any suspected snakebite, even if the person feels well.

If they are unresponsive and not breathing normally, start CPR immediately. CPR takes priority over bandaging.

If the person is unresponsive but breathing normally, gently place them on their side, keep their airway open and keep checking their breathing. Follow the emergency operator’s instructions.

Keep them lying still and reassured. For an arm or leg bite, apply a firm pressure bandage over the bite and along the whole limb, then splint it. Leave the bandage and splint in place for hospital staff. Stay with the person and monitor breathing.

Do not wash, cut or suck the bite, apply a tourniquet, or try to catch or kill the snake.

Based on ANZCOR snakebite guidance and pressure immobilisation guidance. Sources checked 25–26 September 2026.

Read the full first-aid guide →

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