Beaked sea snake

Thought to be the deadliest of the 64 species of snakes that spend the majority of their lives in the ocean, the beaked sea snake delivers its venom via a small pair of fangs at the front of its mouth. This venom contains a powerful toxin that causes paralysis, including of the diaphragm, potentially leading to respiratory failure.

Stonefish

Stonefish stings are said to be intensely painful and lead to swelling of the entire affected limb within minutes, as well as necrosis and sometimes death, if not treated quickly enough, or depending upon the location of the sting. Fortunately fatalities are rare, with heat immersion (which denatures the venom) and the injection of anti-venom first-line treatments.

Blue-ringed octopus

Don’t be deceived by its beautiful markings or the fact that it’s adorably pocket-sized; this family of Pacific and Indian Ocean octopuses boasts one of the most potent venoms in the sea. Their salivary glands produce tetrodotoxin, another poison that rapidly causes paralysiswith potentially fatal consequences.

Stingray

Saltwater crocodile

Great white shark

Lionfish