Invertebrate

Blue-ringed octopus

Hapalochlaena sp.

IUCN status: UnknownWidely sought

A small octopus that flashes iridescent blue rings when threatened; its bite carries tetrodotoxin and can be fatal. A prized macro find on sand and rubble, often on night dives — observed only, never handled.

Max size
~10–20cm including arms
Habitat
Sand, rubble and reef; frequently found on night dives

Best places to dive with Blue-ringed octopus

rareoccasionalcommonly seenpeak season
Alor
Sighting likelihood by month
MonthLikelihood
Januaryoccasional
Februaryoccasional
Marchoccasional
Apriloccasional
Mayoccasional
Juneoccasional
Julyoccasional
Augustoccasional
Septemberoccasional
Octoberoccasional
Novemberoccasional
Decemberoccasional

One of several rare cephalopods on the muck sites alongside mimic octopus and wonderpus; a prized but unpredictable find.

Anilao, Batangas
Sighting likelihood by month
MonthLikelihood
Januaryoccasional
Februaryoccasional
Marchoccasional
Apriloccasional
Mayoccasional
Juneoccasional
Julyoccasional
Augustoccasional
Septemberoccasional
Octoberoccasional
Novemberoccasional
Decemberoccasional

Regularly found on muck sites and night dives, emerging after dark; small and easily missed without a spotter.

Dauin
Sighting likelihood by month
MonthLikelihood
Januaryoccasional
Februaryoccasional
Marchoccasional
Apriloccasional
Mayoccasional
Juneoccasional
Julyoccasional
Augustoccasional
Septemberoccasional
Octoberoccasional
Novemberoccasional
Decemberoccasional

Found on the sandy muck sites such as Secret Corner; a prized find but small and cryptic, so encounters are occasional rather than reliable.

Lembeh Strait
Sighting likelihood by month
MonthLikelihood
Januaryoccasional
Februaryoccasional
Marchoccasional
Apriloccasional
Mayoccasional
Juneoccasional
Julyoccasional
Augustoccasional
Septemberoccasional
Octoberoccasional
Novemberoccasional
Decemberoccasional

Present year-round but small and cryptic; sightings depend on a sharp-eyed guide and are never guaranteed.

Mabul & Kapalai
Sighting likelihood by month
MonthLikelihood
Januaryoccasional
Februaryoccasional
Marchoccasional
Apriloccasional
Mayoccasional
Juneoccasional
Julyoccasional
Augustoccasional
Septemberoccasional
Octoberoccasional
Novemberoccasional
Decemberoccasional

Reported on the sand and rubble sites at Mabul and Si Amil throughout the year. Usually spotted by guides in shells or rubble holes; no seasonality reported.

Malapascua
Sighting likelihood by month
MonthLikelihood
Januaryoccasional
Februaryoccasional
Marchoccasional
Apriloccasional
Mayoccasional
Juneoccasional
Julyoccasional
Augustoccasional
Septemberoccasional
Octoberoccasional
Novemberoccasional
Decemberoccasional

A macro and night-dive find on the sand and rubble sites; venomous, observed only.

Puerto Galera
Sighting likelihood by month
MonthLikelihood
Januaryoccasional
Februaryoccasional
Marchoccasional
Apriloccasional
Mayoccasional
Juneoccasional
Julyoccasional
Augustoccasional
Septemberoccasional
Octoberoccasional
Novemberoccasional
Decemberoccasional

Found on shallow muck and around the Sabang wrecks, most often on night dives. Small and venomous; not seen every dive.

Fleurieu Peninsula
Sighting likelihood by month
MonthLikelihood
Januaryrare
Februaryrare
Marchrare
Aprilrare
Mayrare
Junerare
Julyrare
Augustrare
Septemberrare
Octoberrare
Novemberrare
Decemberrare

Possible year-round; no unsupported peak is applied.

Nha Trang
Sighting likelihood by month
MonthLikelihood
Januaryrare
Februaryrare
Marchrare
Aprilrare
Mayrare
Junerare
Julyrare
Augustrare
Septemberrare
Octoberrare
Novemberrare
Decemberrare

Reported from the rocky bottom and seagrass patches, but genuinely rare and not something to plan a dive around. Never handle one.

Romblon
Sighting likelihood by month
MonthLikelihood
Januaryrare
Februaryrare
Marchrare
Aprilrare
Mayrare
Junerare
Julyrare
Augustrare
Septemberrare
Octoberrare
Novemberrare
Decemberrare

Reported from shallow macro habitat, but cryptic behavior makes encounters unpredictable. Divers should never handle or provoke one.

Sogod Bay
Sighting likelihood by month
MonthLikelihood
Januaryrare
Februaryrare
Marchrare
Aprilrare
Mayrare
Junerare
Julyrare
Augustrare
Septemberrare
Octoberrare
Novemberrare
Decemberrare

Reported on the muck and rubble sites between Bunga and Malitbog, usually at night. Small, cryptic and venomous — look, do not touch.

Sumbawa, Moyo & Sangeang
Sighting likelihood by month
MonthLikelihood
Januaryrare
Februaryrare
Marchrare
Aprilrare
Mayrare
Junerare
Julyrare
Augustrare
Septemberrare
Octoberrare
Novemberrare
Decemberrare

Possible in suitable habitat; no unsupported monthly peak is applied.

Sydney
Sighting likelihood by month
MonthLikelihood
Januaryrare
Februaryrare
Marchrare
Aprilrare
Mayrare
Junerare
Julyrare
Augustrare
Septemberrare
Octoberrare
Novemberrare
Decemberrare

Possible year-round; no unsupported peak is applied.

Tasmania — East & Southeast
Sighting likelihood by month
MonthLikelihood
Januaryrare
Februaryrare
Marchrare
Aprilrare
Mayrare
Junerare
Julyrare
Augustrare
Septemberrare
Octoberrare
Novemberrare
Decemberrare

Possible year-round; no unsupported peak is applied.

Wakatobi
Sighting likelihood by month
MonthLikelihood
Januaryrare
Februaryrare
Marchrare
Aprilrare
Mayrare
Junerare
Julyrare
Augustrare
Septemberrare
Octoberrare
Novemberrare
Decemberrare

Present but a lucky find, usually on sand and rubble patches; venomous, so it is observed, not handled.

Whyalla & Cuttlefish Coast
Sighting likelihood by month
MonthLikelihood
Januaryrare
Februaryrare
Marchrare
Aprilrare
Mayrare
Junerare
Julyrare
Augustrare
Septemberrare
Octoberrare
Novemberrare
Decemberrare

Possible in the region; no unsupported monthly peak is applied.

Sources & last checked

Checked July 2026

Research is source-backed, but conditions and fees should still be confirmed locally.

View 1 source and checking notes

Note on the data: The genus is not assessed on the IUCN Red List, so conservationStatus is recorded as unknown rather than invented.