Article: Blue-ringed octopuses are found across most Australian coastlines and they spend most of their time hiding. Look for small, 12–20 cm (4.7–7.9 in) brown octopuses around rocks and shells, and leave the water immediately if you spot one.  When these creatures feel threatened, they develop bright blue lines and rings, making them much easier to spot. Blue-ringed octopuses aren’t aggressive and are actually quite shy, but they will bite if touched. Most blue-ringed octopus bites are accidental, as it’s easy to touch or stand on one without noticing. Box jellyfish have a bell (body) that looks like a box with 4 corners. Each corner has up to 15, 3 m (9.8 ft) long tentacles. Irukandji are only the size of a fingernail, yet have tentacles that can each extend up to 1 m (3.3 ft) long.  Beaches in Queensland, Northern Territory, and Western Australia are home to box jellyfish and Irukandji. Rely on signals like washed up jellyfish, clouds of small prawns, and calm weather with a northerly breeze, as it can be difficult to spot these types of jellyfish in the water.  Irukandji syndrome develops within minutes of a sting and the symptoms include back pain, nausea, and difficulty breathing. Seek emergency medical treatment and pour vinegar over the site if possible. Bluebottle jellyfish are 2–15 cm (0.79–5.91 in) long and look like thin, blue bubbles. They relatively easy to spot in clear water and the tide is often littered with bluebottle bodies if these small jellyfish are close by in the sea. Don’t touch washed up jellyfish, as they can still sting. Although cone shells look like innocent, pretty shells, they are actually predatory sea snails which have teeth similar to a harpoon. These sea snails are approximately 12 cm (4.7 in) long and they have a bright shell pattern in brown and cream.  When a cone shell is disturbed, the tooth injects a potentially deadly venom into the victim.  Cone shells are found under sand, stones, and weeds throughout Western Australia, Northern Territory, and Queensland.
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Expect blue-ringed octopuses in shallow reefs and coral rock pools. Watch out for box jellyfish and Irukandji at tropical beaches. Check the beach for washed up jellyfish to spot bluebottles. Avoid touching any shells to prevent a cone shell attack.