Can carnivores be good at heart

The 20 most dangerous marine animals in the world

Spines, poison glands, fangs and harpoons - when it comes to warding off enemies or hunting prey, sea creatures are extremely creative. We introduce you to 20 marine animals to watch out for!


The title poisonous beauty does not apply to any sea creature as it does to the elegant lionfish (see photo above), which today occur with various species in the entire tropical belt of the oceans and increasingly also in the Mediterranean. Their signal colors and the pectoral and dorsal fins (with poisonous spines) spread apart in the face of potential threats should be a warning even to laypeople. Caution: Lionfish are not shy, do not give divers the right of way, follow and hunt in the glow of the lamps during night dives.

Injuries from lionfish

Portuguese galley

The tentacles of the Portuguese galley, up to 30 meters long, carry up to 1000 nettle capsules. Photo: Wolfgang Pölzer

With its floating body, reminiscent of a swimming cap, floating on the surface, this state jellyfish is unmistakable. Tentacles up to 30 meters long extend below the surface, equipped with up to 1000 stinging cells per centimeter and trigger pain reminiscent of burns when they come into contact with the skin. Contact leaves unsightly scars and in individual cases can trigger fatal, allergic shocks. More recently, the typical ocean dweller has also been sighted in the Mediterranean. Keep your distance!

General procedure for jellyfish contact


Weever males occur in the Mediterranean, Eastern Atlantic and in the shallow waters of the North Sea. Photo: Paul Munzinger

The musty-looking poison-fin bearers, reminiscent of lizard-fish, spend the day buried in the sand up to their faces. If a bather steps on an animal, the hard fin rays discharge their protein-based poison, which is not fatal, but causes severe pain. Attention: Due to global warming of the water, weever today are not only on the move in the Mediterranean and the Eastern Atlantic, but also in the shallow water of the North Sea.

Treating weever injuries


Large barracudas will fight back if you get too close. Photo: Norbert Probst

It does happen that large swarms of divers approach curiously, but there is no potential danger from large individual animals, above all the great barracuda. In almost every situation the animal will, despite its stately teeth, run away from divers in case of doubt, but accidents in cloudy water are guaranteed. Especially glittering objects such as knives, reflections in the camera dome ports or lamps can arouse their curiosity. By the way, you shouldn't eat large specimens - they often trigger fish poisoning Ciguatera.

Treatment of bite attacks


Stingrays carry a poison sting in their tail. Photo: Norbert Probst

At least since the death of the documentary filmmaker Steve Irwin, it should be known that stingrays are not cuddly toys - even if they are treated that way by "tamers" in the Maldives. The cartilaginous fish are mostly peaceful and only stepping on their body in shallow water is guaranteed to trigger an attack. Intrusive photographers report precise lashes with the tail, whose poison sting can penetrate ten centimeters into the skin. You shouldn't swim over them and keep your distance with your tail raised!

Injuries from injected poison stitches


Triggerfish can be very aggressive during the mating season. Photo: Wolfgang Pölzer

In the mating season, the big Picasso pushers in particular attack every living creature that approaches their nest. You can recognize their clutches by the two-euro-coin-sized holes in the sandy soil that they leave behind with their crooked teeth. If a large triggerfish is swimming up and down excitedly in the coral gravel area, it is better to swim in the opposite direction. It becomes more difficult in open water with European pushers - it rarely happens, but they can also bite spontaneously. Only Neptune knows why.

Treatment of bite attacks

Cone snails

The cone snail's nerve toxin can be fatal. Photo: Paul Munzinger

Collecting mussels and snails while diving should be a relic of the 20th century, but unfortunately the statistics on accidents with cone snails are clear. Anyone who touches them runs the risk of being hit in seconds by the hidden harpoon, which is connected to a neurotoxin gland. The poison cocktails are among the most efficient in the animal kingdom, require intensive medical treatment and can even cost your life.

Conical snail poisoning

Blue ring octopus

When blue-ringed octopuses feel threatened, their blue circles light up. Photo: Gerald Nowak

As soon as danger is imminent, the little golden octopuses make their blue circles glow and even pulsate. The cephalopods, which are barely more than five centimeters in size, release the same neurotoxin via their parrot's bill that puffer fish have: their tetrodotoxin can lead to ventricular fibrillation and respiratory arrest within two hours. With ventilation and expert treatment, no consequential damage remains. Blue-ringed octopods only live in the Indo-Pacific and, despite their hidden way of life, are quite common, especially in tidal pools.

About the strong poison of the blue-ringed octopus

Bull sharks

Bull sharks have little inhibition about divers. Photo: Tom Vierus

Just like tiger sharks, bull sharks are also attracted to relevant locations and often also fed. Chance encounters with the corpulent gray sharks, which are also found in tropical rivers and lakes, are uncommon on most reefs around the world. Because the respectful animals have a low inhibition threshold towards divers, can often approach unnoticed and can be penetrative, they are one of the few shark species where you really need to be careful. In cloudy water, in pairs or even on solo dives, meeting them can be uncomfortable and dangerous.

Shark alarm in the island paradise of La Réunion

Fire coral

Fire corals nettle extremely strongly. Photo: Paul Munizinger

Fire corals are the punishment for “beginners”: In the Red Sea and the Maldives, the rapidly growing stony corals, which are widespread worldwide, form large colonies that are home to large cities made of nettle cells. When they come into contact with the skin, they discharge and, within a short time, cause itching and blistering reminiscent of nettles. Days later, they begin to wet. In severe cases, the use of anti-allergic ointments is recommended. Contact with fire corals can leave permanent scars!


Crocodiles are really not cuddly toys. Photo: Michael Vogelsang

An encounter with such a stalker cannot be compared to a fish. With the exception of certain regions around Australia, encounters are very unlikely because the reptiles in the sea prefer cloudy water and mangroves. For estuarine crocodiles, humans are prey, and Nile crocodiles are also high-risk candidates, while American crocodiles, with which they snorkel in Mexico and Cuba, have a more peaceful disposition. Nevertheless: Always keep eye contact and never go into the water without a backup diver!

Luminous jellyfish

Luminous jellyfish are really nice to look at, but please don't touch them! Photo: Wolfgang Pölzer

The most famous fire jellyfish in Europe owes its species name “The one that shines at night” to a light luminosity that is visible in the dark when colliding with boats, for example. Skin contact with the catching tentacles covered by nettle cells triggers severe pain which, although it leaves pustules, only leads to nausea or vomiting in severe cases. In recent decades, there has been a mass occurrence in the Mediterranean and the Atlantic - a phenomenon that is justified by overfishing, water pollution and climate change.

Sea snakes

Sea cobras are extremely curious. Photo: Gerald Nowak

Most sea snake encounters are experienced by divers with the striped sea cobras, which are much smaller than their native relatives around Australia and the open seas. The reptiles are very curious and sometimes mistake a jacket pocket for a crevice. As bad as this idea may be, the venomous snakes have a deadly poison, but their poisonous teeth lie far back in their mouth, which is so small that it only fits into narrow areas of skin such as the folds between the fingers. So stay cool!

Saber-toothed slimy fish

Little villain in the reef: saber-toothed slimy fish nibble on other fish. Photo: Norbert Probst

Provided with human attributes, the saber-toothed slimy fish is simply considered mean. In fact, it lies in wait for larger fish and, as a supposed cleaner fish, pretends to be useful in personal hygiene, only to then bite powerfully and tear large pieces of meat from the victim's body. For this purpose, the unsympathetic fish is equipped with fangs that are surrounded by poisonous glandular tissue. And just as cleaner fish try their luck with diving underwear, saber-toothed slime fish also bite, which is as enjoyable as a wasp sting.

Moray eels

Those who do not feed or press the moray eels need not fear attacks. Photo: Norbert Probst

Their snake-like appearance with their open mouth and bared teeth gave morays a bad image even in the pioneering days of diving. The fact is that unprovoked, aggressive behavior towards humans is rather uncommon in all species. Accidents usually happen when the animals are fed or brought into distress, for example by carelessly holding onto the entrance to the den. Also because their teeth contain residues of prey, moray eel bites are highly infectious and must be disinfected immediately.

Treatment of bite attacks


Sky-gazers have poisonous spines behind their gill covers. Photo: Herbert Frei

As its name suggests, the star or sky gazer sees his world from a frog's perspective, out of the sand. Its character head with the dagger-like teeth makes it an expressive photo motif. Similar to stonefish, these ambulance hunters are reluctant to give up their camouflage. Sky-gazers defend themselves with powerful poisonous spines, which are arranged behind the gill covers. Some stargazers also give out electrical surges.

General procedure for poison injuries

White shark

The great white shark is one of the top predators in the sea. Photo: Sam Cahir

The probability of encountering a great white shark as a diver outside of the classic hotspots tends towards zero. Because the animals as ambulance hunters usually attack their prey from below, divers are exposed to a much lower risk than swimmers or surfers. Close to the ground, encounters with curious “whites” almost always turn out well. On the surface of the water away from the boat, nobody wants to get too close to a great white shark unprepared - and encounters outside the cage are and will remain something for experts!

Great White Shark - Successful Evolution Model


Stonefish carry a strong protein poison in their dorsal spines. Photo: Wolfgang Pölzer

In addition to protecting the environment, stone fish are the best argument to keep your distance from the reef. The masters of camouflage fuse with the reef like no other sea creature and their potent protein venom is potentially deadly. Because they move only involuntarily, they also pose a risk for bathers, especially since their lime-supported dorsal fin spines penetrate thin soles. Wading should be avoided, especially in the area of ​​scree. Stonefish can be found locally between the Red Sea and the South Pacific. Caution: Stonefish hide in the sandy bottom even far from the reef.


Scorpion fish are stalking hunters and you should keep your distance. Photo: Wolfgang Pölzer

Scorpionfish belong to the huge family of scorpion fish and are found in all oceans. Although the fish, which are between a meter and a few centimeters in size and covered in shreds of skin, often come in signal colors, their habit of lurking openly on rocks or in caves for prey is annually the undoing of careless divers. The protein poison is not fatal, but extremely painful. To prevent further damage, it should be rinsed with hot water.

Yellow hair jellyfish

Yellow hair jellyfish live in the Atlantic as well as in the North and Baltic Seas. Photo: Martin Prochazkacz / Shutterstock

Its popular name lion's mane describes the swirling structure of over a hundred tentacles below the large hood quite aptly. This large cold-water jellyfish is found in the Atlantic as well as in the North and Baltic Seas. As with the Portuguese galley, its tentacles can grow 30 meters long and are not even noticed by careful divers or even swimmers. The allergic reaction after a painful sting of the nettle tubes is rather harmless. Washed up animals should not be touched as their stinging cells can still be active.

Treatment of bruises