Top 10 Scariest Sea Creatures

15 April 2009 By Kate Hubert

Ever wonder what’s beneath you when you’re swimming in the sparkling, serene waters around the boat? Here’s our Top 10 Countdown of seriously scary marine lifeforms, where they’re found and what to do if you get bitten.

Where found: These green meanies live in reefs and underwater crevices and caves worldwide.
Their bite causes non-fatal injuries – but their razor-sharp teeth can cause massive bleeding and infection. Moray eels may bite if they sense they or their territory is threatened. They also may attack spearfishermen if they are carrying bleeding fish. Don’t taunt them, or explore unknown crevices with your hand if diving or snorkelling. If you are hunting lobsters – watch out!
Treatment: If bitten, get out of the water and apply pressure to stem any bleeding. Get medical help to make sure the wound is cleaned.


Where found: around coral reefs, often near caves and crevices

Their sting is usually survivable – but it can take months to recover. Venomous spines on the fins make nasty puncture wounds. They cause pain and swelling, as well as difficulty breathing and paralysis. Don’t get too close to these fish or aggravate them. The venom in the spines can be active for days, so also be wary of discarded spines.

Treatment: Immerse affected limbs in hot water. Spines must be carefully removed to avoid gangrene; a doctor may need to check the area using an X-ray.


Where found: tropical seas, especially the Pacific and Caribbean

This poisoning occurs when you eat a fish that has eaten plankton containing ciguatoxin. It’s not fatal, but in addition to causing the usual food-poisoning symptoms, the effects can last for decades, causing long-term disability. They can be triggered later by other foods and exercise. The poison even can be transferred via sexual contact!

Warning: Don’t eat reef fish unless you are sure you’re in a ciguatera-free area. Cooking does not neutralize the poison.

Treatment: There is no effective antidote or treatment. As for other types of food poisoning – keep the patient hydrated.


Where found: warm and tropical seas, on sandy sea beds

The spine on a stingray’s tail can be fired if threatened – injuries often occur to a diver’s lower legs after a stingray has been trodden upon in the shallows. The sting causes pain and inflammation, and rarely has more serious effects such as convulsions. It is rarely fatal – the main problems it can cause are due to post-sting infection. These are non-aggressive creatures that only sting if threatened. (“Crocodile Hunter” Steve Irwin’s death was a horrible fluke because the spine pierced his heart.) Do the “stingray shuffle” (slowly moving your feet along the sand to warn stingrays of your presence) in shallow water if paddling – they can detect your movement and will swim away. Don’t hassle or scare them if snorkelling or diving.

Treatment: If stung, seek medical help to make sure the wound is properly cleaned, and get a tetanus shot.


Where found: tropical seas (except the Atlantic)

Technically, sea snakes have more potent venom than many land snakes such as cobras – but human deaths from their bite are extremely rare. A sea snake’s bite releases very little venom. Its teeth are weak and often found at the back of its mouth; you virtually have to stick your finger down its throat to get envenomated. Problems arise because the bite often doesn’t hurt – hence help may not be sought promptly.

Take extreme care if handling sea snakes – they aren’t aggressive but it’s best to look rather than touch if snorkelling/diving.

Treatment: If bitten, immobilize and pressure-bandage the victim; do CPR if necessary and get medical aid to administer anti-venom.


Where found: tropical seas, often near coral and rocks, as well as on sandy/muddy bottoms

Stone fish have venomous dorsal spines. Their sting can cause death – symptoms include excruciating pain, swelling, tissue necrosis (death), temporary paralysis and shock, which may lead to death.They are very well camouflaged and their spines can pierce shoes. Take great care when reef walking or paddling in shallows, even if wearing thick booties or reef shoes.
Treatment: Immerse the affected limb in hot water, get the victim to a hospital – luckily, there is anti-venom that can be administered.

4. IRUKANDJI (small jellyfish)
Where found:
Australia, the Pacific, in deep/offshore water but may be swept onto reefs
Stings from the tentacles of this small (two centimeter bell) jellyfish are not too painful but cause backache/headache and shooting pains in muscles and can lead to fluid on the lungs and even death. Sixty people are hospitalized each year in Australia due to Irukandji stings.

Take care when snorkelling and diving in deeper water – wear a wetsuit or stinger suit.
Treatment: Vinegar may help – but get proper medical attention or take the victim to a hospital as soon as possible. There is no anti-venom.


Where found: Mud and sand flats; in tidal zones of tropical seas

These creatures fire a small, harpoon-like venomous dart that attacks the nervous system. It causes weakness, disturbed vision and hearing, can lead to paralysis of the respiratory system – and it can be fatal. Don’t handle live shells – although they can be very pretty. Have a quick check in local guide books so you know what cone shells look like.

Treatment: Call an ambulance. Meanwhile, apply pressure, and you may need to do CPR.


Where found: worldwide

About four people are killed each year by sharks. In 2008, 59 “unprovoked” attacks on humans were reported. (This compares to the tens of millions of sharks killed by humans each year....) There are around 30 species of shark that can be dangerous to humans. Although a few, like Oceanic White Tips, do seem to think of us as prey, most attacks are caused by mistaken identity – surfers on boards looking like fat seals, spearfishermen with bleeding fish, etc. Attacks are most common in shallow, turbid water – avoid the surf zone, especially from dusk ’til dawn. If attacked – fight back. Attack gills, eyes and get out of the water as soon as you can (of course!).

Treatment: Get medical help; stem bleeding using pressure.


Where found: Australia, Indo-West Pacific and Southeast Asia. Not usually found over coral (e.g. the Great Barrier Reef is safe) or in deep water

Box Jellyfish stings are usually fatal. Excruciating pain can lead to shock and drowning in less than four minutes before help can be sought – don’t swim alone! At least one death per year is reported in Australia – but often there are many more. These jellies are found farther inshore than Irukandji. They move inshore with the tide and in calm seas they can jet along at up to four knots. They have a 20cm, box-shaped, pale-blue bell and tentacles up to three meters long. When attacked, the creature’s stinging cells or nematocysts can become embedded in your skin.They are frequently found in northern Australian waters from October through April, and off Queensland and northwestern Australia in November through March. Wear a stinger suit or wetsuit if you must swim in an area that may be infested.

Treatment: Call an ambulance and flush with vinegar to stop the nematocysts from firing. You may have to commence CPR. Use ice and antihistamines for pain.