The sea's most dangerous creatures

Lionfish
You'd expect fish enthusiasts to steer well clear of a sea creature named after something as ferocious as a lion. However, this is far from the case. The beautiful yet poisonous lionfish is a very popular pet. Although no deaths have been reported so far, the lionfish has poisonous dorsal spines which can cause extreme pain to its victims.
This means that those who do choose to keep lionfish have to be very careful when cleaning out their aquarium - just one stab can cause severe headaches and vomiting.
The species is native to the Indian and Pacific Oceans and is a true survivor. This is evident from a 2009 incident when a hurricane destroyed a tank in Miami, causing six lionfish to escape. The fish bred very rapidly and spread along the East Coast to the Bahamas and Bermuda, and have now reached the Caribbean. Fortunately, the fish will only attack people when provoked

Stonefish

In contrast to the striking appearance of the lionfish, the stonefish is a master of camouflage and can be virtually indistinguishable from a rock on the sea floor. This makes them extremely dangerous, as it's all too easy for swimmers and divers to stumble across one unexpectedly. They live in shallow waters in the tropical Pacific and Indian Oceans, which are - unfortunately - top destinations for snorklers.
If you stand on one of the stonefish's 14 venomous spines, make sure you make a quick dash to the emergency room. On top of terrible pain, the poison can cause paralysis if not treated immediately. The agony is said to be so severe that some victims have begged to have their limb amputated rather than live another moment with the pain from the spines.

Box jellyfish

In Australia, it's commonplace for lifeguards to wear tights on their arms and legs. Although this may be an odd choice of attire to go swimming in, it can help save their lives. This is because tights can help protect against the sting of the box jellyfish, which is the most poisonous animal on earth. The jellyfish's sting is only effective when contact is made with the skin and, over the years, lifeguards have learned that wearing tights prevents them enduring agonizing pain, severe vomiting or even death at the hands of these most lethal of sea creatures

Stingray

It wasn't until 2006 that most people realized just how dangerous stingrays can be. Fearless TV personality Steve 'Crocodile Hunter' Irwin died after suffering a stab from one of these graceful creatures, which surprisingly kill more people annually than sharks.
Overall, however, the ray is not aggressive and will only attack when provoked. The poison from the stab wound causes extreme pain and swelling, as well as infection.

Blue-ringed octopus

While most of the stings from the creatures in this gallery will cause immediate pain, the bite of a blue-ringed octopus might feel comparatively harmless at first. But don't be fooled into thinking this attack is any less lethal than its more famous counterparts. The cephalod's neurotoxic poison can gradually lead to paralysis and eventually death.
The blue-ringed octopus is rarely larger than 20 inches long and, as they're not an obvious threat, the danger can be overlooked. There's no antidote for the bite, so if you encounter one in the water your best bet is to avoid it.

Great white shark

With rows of sharp teeth and powerful jaws, the legendary great white can bite an arm or leg in half in one go. Obviously, this is a deadly creature which in many ways is as dangerous as it looks, but it's not quite as lethal to humans as you might think.
Movies like Jaws have spread the misconception that sharks will attack humans at any given opportunity. However, in reality, more people are killed annually by wasp and bee stings than by attacks from the world's largest predator. When a shark does attack a human, it's usually by accident and it will most likely have mistaken a surfer or swimmer for its more usual prey,such as seals.
Although 75 percent of the attacks that do occur aren't fatal, they can have serious consequences such as deep flesh wounds that can often lamputation

Tiger Shark

While the great white is much more notorious, you should be just as scared of the tiger shark if you come across one in the briney deep. This gigantic fish is, in fact, more dangerous to humans as its hunting ground is generally closer to the coast.
While most fish are pretty picky eaters, this beast will eat almost anything it can lay its jaws upon - other sharks, boat parts, old tyres and license plates are among the things that have been found in their stomachs.

Sea Snake

It's a good job the sea snake is not aggressive, because one bite from this naturally shy creature can cause serious damage. Like all venomous snakes it has long fangs in its upper jaw, and the poison from these can lead to permanent nerve damage in humans. They're primarily found in shallow waters in the Pacific and Indian Oceans, with the most dangerous type being the compressed sea snake.

Fire coral

Although the name suggests otherwise, fire coral is not in fact a coral but is more closely related to jellyfish and anemones. They can give off a mercilessly hard sting with invisible tentacles and, although not deadly, an 'attack' can have unfortunate consequences. Following contact, victims will feel an intense pain that can last anywhere between two days and two weeks. Fire coral's victims are usually experienced divers who mistake it for normal coral.

Sea urchin

Sea urchins hardly look cuddly in appearance, but despite this there are still plenty of people who fall victim to the razor-sharp spines of these tiny creatures. The needles are long enough to wreak serious damage to whoever stands on them. On top of the intense pain, the urchin's spines break on contact and can cause infection, and in many cases they have to be surgically removed.
Sea urchins generally aren't poisonous, but there are exceptions. Toxopneustes pileolus, for example, is one of the most dangerous types out there. To the untrained eye, their spines can look like flowers, but they're extremely venomous and can lead to paralysis and even death.