The ocean covers more than half of the world's surface and many of the animals that live there are still undiscovered. There is no doubt that it is a beautiful place filled with creatures that almost seem otherworldly. The creatures that we do know of have been studied in depth, and we now know if it is safe to either interact with and/or consume these animals, as well as if they hold any medical significance.
Much like the animals found on land, there are some from the ocean that can be extremely dangerous. Some of the creatures that have been labeled as deadly include animals as large as the great white shark and the Humboldt squid, and animals as small as the Irukandji jellyfish and the Glaucus atlanticus, and seemingly harmless creatures like the stinging hydroid and sea anemone.
How well do you know the creatures in the ocean, specifically the ones that are a danger to both humans and many of the other animals living there? If you would like to test your knowledge, then this is the quiz you need to take!
Lionfish is a genus of venomous marine fish that were native to the Indo-Pacific waters but can now be found in different parts of the world. The fin rays of these fish are poisonous and, in some people, the venom can cause vomiting, convulsions and in rare instances – death.
Stingray is cartilaginous fish that can be found in tropical and subtropical seas and oceans around the world. They are not very aggressive creatures, but they have been known to attack humans with their poisonous stinger and sharp barb when they feel threatened.
The yellow boxfish is a type of boxfish that can be found in the reefs of the Pacific, Indian and Atlantic Oceans. The fish whose bright color fades as it ages releases toxic proteins from its skin when it feels stressed or injured, killing fish in the surrounding waters.
The great white shark is a large mackerel shark that can be found in the coastal waters of every ocean. Some of these natural predators can grow to lengths exceeding 15 feet are responsible for the largest number of unprovoked attacks on human beings.
The electric eel is an electric fish that is not really an eel but a knife fish. Three of the eel’s organs can produce electricity, which can shock up to 850 volts for a few milliseconds. Although it is not able to kill a human adult, it can cause a painful numbing shock.
Marlins are fast swimming fish that have an elongated spear-like snout which is typically hunted in sports fishing in many tropical regions. There have been quite a few incidents where humans have been stabbed/impaled by these animals.
The textile cone, also called the cloth of gold cone, is a species of sea snails that can be found in the waters of the Red Sea and the Indo-Pacific Ocean. They are predatory animals whose venom has caused the deaths of a few human beings.
The Dubois sea snake, also called the reef shallows sea snake, is a species of sea snakes that can be found in the waters surrounding Australia, New Caledonia, and Papua New Guinea. It is also one of the most venomous snakes in the world.
The tiger shark is a species of migratory sharks that can grow to lengths exceeding 16 feet. Typically found in tropical waters around the Pacific islands, these near threatened species of sharks have the second most recorded fatal attacks on humans.
The pufferfish, which is also known as the blowfish, is a family of fish that is known to have large external spines and to puff up. Many of the species are among the most venomous animals in the world, and they can cause organ damage if ingested.
The box jellyfish is a group of over 50 species, some of which produce an extremely potent venom. The stings from this animal are extremely painful and have been known to be fatal, mostly when stung by the larger species.
The Striped surgeonfish, which is also called the lined surgeonfish, is a species of surgeonfish that have been seen in reefs around the Indian and Pacific Oceans. The fish’s sharp spines, which are seen on its caudal peduncles, are known to be venomous.
The flamboyant cuttlefish is one of the many species of cuttlefish found in the tropical Indo-Pacific waters. Its boldly colored flesh (of yellow, maroon, brown, white, and red) contains acids that make it extremely toxic.
The blue-ringed octopus is a genus that is made up of four extremely venomous species of octopus that can be found in reefs and pools from Japan, all the way down to Australia. Their venom contains a powerful neurotoxin that can lead to total body paralysis.
The Portuguese man o’ war is a marine hydrozoan which can be found in the Indian, Pacific, and Atlantic Ocean. It has very long tentacles that deliver a venomous and painful sting, which is enough to kill a human being.
The flower urchin is a common species of sea urchin that can be found in seagrass beds and coral reefs in the Indo-West Pacific Ocean. When touched, it can deliver stings, which cause extreme pain that requires medical assistance/treatment.
The beaked sea snake is a venomous species of sea snakes that can be found in the tropical waters of the Indo-Pacific Ocean. The snake is responsible for more than half of the bites caused by sea snakes, with quite a few of them resulting in death.
Stonefish are extremely venomous fish that are known to reside in the coastal water of the Indo-Pacific Ocean. Their stings which are extremely painful and can result in death if not treated. They are usually caused when people accidentally step on them.
Stargazers are a family of fish whose eyes are located on the top of their heads and can be found in all marine water around the world. They are known for their two large venomous spines, and there are some species that are also able to deliver electric shocks.
A piranha is a freshwater fish that can be found inhabiting the rivers, lakes, and reservoirs of South America. These animals are known for their extremely sharp teeth, which rarely pose a significant threat to human, but there have been reported fatalities in the region.
Moray eels are a family of eels that can be found swimming in waters all over the world. Not only are their bites extremely painful, but some species contain ciguatoxins which, if ingested, can lead to gastrointestinal and cardiovascular problems.
Hammerhead sharks are a group of sharks named as such because of their flattened and laterally extended hammer-shaped cephalofoil. They can be found in warmer waters along the coastline where they swim in schools. No human fatalities have been recorded, but there have been some unprovoked attacks.
The Lion’s mane jellyfish, also known as the giant jellyfish, is the largest known species of jellyfish in the world and can be found in the cold waters of many oceans. Stings from this jellyfish usually cause redness and temporary pain at the site of contact.
The titan triggerfish, also called the giant triggerfish, is the largest species of triggerfish and can be found in reefs and lagoons in the Pacific Ocean. They usually stay away from humans, but females have been known to attack during the reproductive season, with some bites requiring medical attention.
The barracuda is a ray-finned saltwater fish that can be found in tropical and subtropical waters around the world. For many years, they have earned the reputation of being dangerous to swimmers, often biting them, but no fatalities have been reported.
The Humboldt squid, also called the jumbo flying squid, is a large squid which can be found in the Humboldt current of the Eastern Pacific Ocean. They have been known to be aggressive to humans, which people believe manifests during its feeding time.
The yellow-bellied sea snake, which is named for its brightly colored underbelly, can be found in all of the tropical oceanic waters except the Atlantic. It has a highly potent venom that can cause damage to skeletal tissue and neuromuscular paralysis.
The crown-of-thorns starfish is a large venomous starfish that is so named because of the thorn-like spines covering the fish’s upper surface, giving it the appearance of the crown of thorns from the bible. The spines perforate the tissue of predators and unsuspecting persons which can cause persistent bleeding and stinging pain.
The saltwater crocodile, informally called saltie, is one of the largest living reptiles with males reaching lengths exceeding 20 feet. They are predators who can live in saline habitats and have been known to attack a variety of animals including humans and sharks.
Fire coral is a genus of marine organisms that are closely related to hydrozoans rather than coral but is so named due to its physical characteristics. Often mistaken for seaweed, contact with it causes intense pain that can last from days to weeks.
Bull sharks are requiem sharks found in warm, shallow coastal waters around the world. Known for their aggressive nature, they can live in both fresh and salt water, and the larger ones are the usual culprits of the near-shore shark attacks on humans.
The Irukandji jellyfish is an extremely venomous species of box jellyfish that has an approximate size of one cubic centimeter, making it the smallest and most venomous jellyfish in the world. It is found only in Australia, and symptoms of a sting include hypertension, vomiting, tachycardia, and in some cases death.
The leopard seal, also called a sea leopard, is one of the largest species of seal found in Antarctica. They are top-order predators that have been known to stalk and attack humans, although they are rare.
Sea anemones are predatory marine animals from the Cnidaria phylum. They are seen adhered to rocks, rarely changing their position, and swing with the water. Their tentacles contain cnidocytes with venom known to paralyze its prey.
The sea wasp is a species of box jellyfish that many have referred to as “the most lethal jellyfish in the world” as it is responsible for over 60 deaths within 12 years. Found in coastal waters from Australia to Vietnam, its powerful venom can cause death within two to five minutes if left untreated.
The blue-spotted ribbon tail ray is a species of stingray that can be found at depths of 100 feet in the tropical Indian and the Pacific Ocean. Known for its striking color pattern, the ray has venomous tail spines that it uses when it feels threatened.
The Atlantic sea nettle is a species of jellyfish found in the tropical and subtropical waters of the Indian, Pacific, and Atlantic Oceans. Their tentacles are covered with cnidocytes, which upon contact eject a venom-coated filament into its targets. In humans, it causes a painful rash.
The Glaucus atlanticus, also called the blue sea slug, is a small pelagic slug known for floating upside down and its unique blue pattern. They feed on venomous creatures storing the venom for their own protection and handling of the slug can cause very painful and sometimes dangerous stings.
Stinging hydroid, sometimes called fireweed or stinging seaweed, is a marine organism found in clumps on coral and rocky reefs all over the world. When touched, they cause blistering of the skin and rashes.
The old wife is a species of fish endemic to the coastal waters surrounding Australia. Studies on this fish indicated that while there is no venom groove or gland, the bony, knife-like spines can inflict painful venom on its targets.