Daniel Brown, an Australian naturalist, almost stepped in a stonefish while exploring rock pools in the suburb of Lee Point near Darwin in Northern Australia. These fish are masters of camouflage that can survive for 24 hours out of the water and can easily be mistaken for misshapen rocks by unsuspecting beachgoers.

Brown shared his experience on Facebook with a warning to the public to be careful when stepping on the beach as the dangerous fish could be there, camouflaged as rocks.

Australia's Deadliest Animals
(Photo : Ian Waldie/Getty Images)
A Stonefish (centre) is pictured at Oceanworld Aquarium January 24, 2006 in Sydney, Australia. The Stonefish is well camouflaged in the ocean, as it is a brownish colour, and often resembles a rock.

Stonefish Uses Camouflage to Hunt

Associate Professor Bryan Fry who leads the Venom Evolution Laboratory at the University of Queensland told Newsweek that stonefish can be found throughout the shallow coastal waters of Northern Australia and can be extremely common in the right places.

Camouflage is the best technique for stonefish as they hide to ambush their prey. Nestled among the rocks and sand, these fish wait for unsuspecting prey to swim by before they dart out and attack the victim in 0.015 seconds.

According to Oceana, stonefish can blend so perfectly with their surroundings that their preys, predators, and humans have trouble seeing them. Their preferred habitat is the coral and rocky reefs, which match their color to their surroundings to hide. Some were even observed growing algae on them, giving them extra protection and allowing them to successfully ambush their prey.

They mainly eat other reef fishes and some bottom-dwelling invertebrates while waiting patiently for them to come near. Stonefish have powerful jaws and large mouths that create so much pressure to make it easier to suck down their prey and swallow them whole.

Humans rarely eat stonefish and these fish are not a targeted fishery, although some individuals could get caught for the private aquarium trade. Currently, their population status is unknown and there is no evidence that human activity affects or threatens them. However, human activity does threaten the coral reefs where they live.

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Most Venomous Fish in the World

Stonefish only use their venom when they need to defend themselves. Per the Australian Museum, stonefish are the most venomous fish in the world. The fish has 13 stout spines in the dorsal fin that can inject highly toxic venom, which causes intense pain that is enough to kill. There have been many reports about Pacific and Ocean islanders being killed by the fish but none so far in Australia.

Andrew Wilner, a neurologist in the US, told the Museum that stonefish venoms have both cardiovascular and neuromuscular toxicity. It is a mix of enzymes and non-enzymatic proteins. Not much is known about the mechanism of action of stonefish venom but the Reef Stonefish and Estuarine Stonefish have different types of venom.

But Fry said that the venom prevents blood from clotting, causes damage to muscles, affects the rhythm of the heart, and may also cause paralysis. In severe cases, the venom can cause a cardiac collapse that may result in death.

Experts say that the best way to avoid getting stung is to leave stonefish alone as they do not start fights but will sting in defense. An antivenom was developed in 1959 that reduces the likelihood if ever a human getting stung, but many people still suffer every year. Very hot water, and not scalding, may relieve the pain but medical treatment will save a life.

RELATED ARTICLE: Deadly Stonefish: Scientists Unlock Mysteries Behind This Toxic Fish's Venom

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