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Nile crocodile -

The Nile crocodile is an apex predator that can prey on any animal, including humans, within its range.

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Sea snake -

Sea snakes have adapted to living fully in water and are unable to move on land. They are highly venomous, with the beaked sea snake being the most poisonous species. Its venom is eight times more toxic than that of a cobra.

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Tiger shark -

This shark species, known for its dark striped body pattern resembling that of a tiger, is responsible for the second highest number of recorded fatal attacks on humans, trailing behind the great white shark.

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Great white shark -

Steven Spielberg's film 'Jaws' in 1975 negatively affected the reputation of the great white shark. However, its reputation was already pretty bad considering that it is responsible for the highest recorded number of shark bite incidents on humans.

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Tigerfish -

Tigerfish are agile predators known for their streamlined physique, muscularity, and aggressive nature. These capable hunters often work together in groups and possess razor-sharp teeth that rival those of piranhas. Interestingly, the African tigerfish holds a unique distinction as the first freshwater fish to have been observed and proven to attack and capture birds while they are in mid-flight.

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Pufferfish -

Most pufferfish species are poisonous, with some being highly toxic and ranking among the most venomous vertebrates globally. However, certain species are prized as a culinary delicacy in Japan.

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Box jellyfish -

There exist a minimum of 51 varieties of box jellyfish. Certain ones generate highly potent toxins and have attained the rather disreputable distinction of being among the most venomous creatures in the world.

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Harmful algal bloom -

Harmful algal blooms, as defined by the National Oceanic and Atmospheric Administration (NOAA), "occur when colonies of algae—simple plants that live in the sea and freshwater—grow out of control and produce toxic or harmful effects on people, fish, shellfish, marine mammals and birds." Although uncommon, these blooms can result in severe illness or even death for individuals. The photograph displayed exhibits an algal bloom in Lake Erie in North America in 2011, captured by a NASA satellite.

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Great barracuda -

The barracuda, a substantial predatory fish, has the capability to attack humans when provoked. There have been documented cases of barracudas jumping out of water and causing harm to boaters.

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Stonefish -

Members of the stonefish family pose a threat to humans as they are toxic, dangerous, and can even cause fatalities. In fact, they are the deadliest fish known to man.

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Diving bell spider -

The diving bell spider is a unique spider species that is primarily found underwater. They achieve this by constructing an irregular diving bell made of silk, which they fill with air from the surface. Humans who happen to disturb this aquatic spider may experience a painful bite, resulting in inflammation, vomiting, and mild fever that subsides after a few days.

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Water moccasin -

The water moccasin is a type of pit viper found in the southeastern United States. It is the only semi-aquatic viper in the world and can grow to be large in size. Its bite is extremely painful and can be deadly.

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Snakehead -

Snakeheads are a type of predatory fish that have a fascinating ability: they can breathe air using gills, enabling them to move short distances across land. Although originally from Africa and Asia, the presence of this species in the United States has raised concerns among environmentalists. These invasive fish are known for their potential to transmit parasites or diseases.

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Lionfish -

Lionfish are distinctive due to their venomous fin rays, which are an unusual trait among fish living on reefs in the American East Coast and Caribbean. If stung by one, anticipate intense pain, nausea, vomiting, fever, difficulty breathing, convulsions, and dizziness.

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Saltwater crocodile -

Saltwater crocodiles are highly active compared to other crocodilians, and they display significant aggression towards humans who unintentionally invade their habitat. Among all crocodile species, the saltwater crocodile and Nile crocodile exhibit the strongest inclination to perceive humans as potential prey.

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Electric eel -

While rare, there have been documented cases of fatalities resulting from the shock of an electric eel. A person may be incapacitated by a single electric jolt, leading to drowning, while multiple shocks can potentially induce heart failure.

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Candiru -

The candiru is a type of freshwater catfish that can be found in the Amazon Basin. There have been claims that the smaller ones have a propensity for entering the urethra of unsuspecting swimmers, using sharp barbs to anchor themselves in place. Once inside, they proceed to feed on their unfortunate host from within. This terrifying tale is enough to make you keep your legs tightly crossed for quite some time!

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Sting ray -

Sting rays are typically passive creatures and will only attack humans if provoked. If a person comes into contact with the stinger in the tail, it can cause local trauma, pain, swelling, and muscle cramps due to the venom.

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Blue-ringed octopus -

Known as one of the world's most lethal marine creatures, this magnificent mollusk is also incredibly beautiful. Despite their generally mild temperament, they become perilous to humans when approached with aggression.

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Cone snail -

Cone snails, a species consisting of approximately 600 venomous and predatory varieties, inject conotoxins into their prey to immobilize them. Due to their potential to "sting" humans, caution must be exercised when dealing with live cone snails. Accidental contact triggers a deadly discharge of toxins, resulting in fatal consequences. Among these species, the geography cone and the textile cone (pictured) are notably responsible for human fatalities.

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Weeverfish -

The weeverfish has been known to catch beachgoers off guard. These fish lie hidden in the sand, only revealing their eyes in the shallow water. Unfortunately, anyone who accidentally steps on one will certainly experience a painful sting from the venomous spines on its dorsal fin and gills.

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Hippopotamus -

Hippos, known for being mostly herbivorous and semi-aquatic mammals, are globally recognized as highly dangerous creatures owing to their aggressive and unpredictable behavior. The volatile nature of hippos puts small boats at risk of capsizing, exposing passengers to potential injury, fatality, or the risk of drowning.

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Piranha -

The piranha is notorious for its powerful bite, which is one of the strongest among bony fishes. Its jaws are equipped with rows of sharp teeth that can swiftly tear apart prey.

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Anaconda -

The common or green anaconda is the heaviest snake on Earth and the second longest, after the reticulated python. These snakes inhabit the swamps, marshes, and sluggish rivers of the Amazon and Orinoco basins. Although it is highly uncommon, there have been instances where individuals have been bitten and subsequently constricted by anacondas. Fortunately, they were rescued before the incidents turned deadly. 

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Bristleworm -

The bristleworm stands out as the most perilous of worm species. It inhabits all depths of the Earth's oceans and can endure a wide range of temperatures. It is important to note that under no circumstances should one handle these worms with bare hands. The bristles of these worms are incredibly delicate and can become embedded in the skin, resulting in an intense itching sensation. The image presented here showcases a specific type of bristleworm known as a ragworm.

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Needlefish -

The needlefish, a slender and smooth fish, lacks aggression, toxicity, or a lethal bite. Surprisingly, its threat comes from its peculiar skill in taking flight. These fish are infamous for propelling themselves out of water at astonishing velocities. Anyone unfortunate enough to cross paths with these aquatic projectiles faces the grave danger of being severely impaled.

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Sea lion -

Do not be deceived by the adorable appearance of sea lions. Despite their charm, these highly nimble creatures are capable of launching a rapid attack when they feel agitated or threatened. While instances of assaults on humans are uncommon, approaching an adult sea lion within 2.5 m (8 ft) can pose a considerable danger.

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Caribbean fire sponge -

There are an estimated 5,000–10,000 identified species of sponges that exist in the oceans worldwide. While the majority of these sponges pose no harm to humans, there are exceptions like the Caribbean fire sponge (depicted), which can lead to a serious skin rash upon contact.

Sources: (World Health Organization)(National Oceanic and Atmospheric Administration)

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