Box jellyfish are invertebrates belonging to the class Cubozoa, named for their cube-shaped medusae. Cubozoans are categorized separately from other types of jellyfish and are considered more complex than Scyphozoans. Likewise, Chironex fleckeri (sometimes simply called “the Box Jellyfish”), the best-known species of box jellyfish, is only one of a category which actually contains about 19 different species. The name sea wasp is also applied to some species of Cubozoans, including the aforementioned Chironex fleckeri and Carybdea alata. Box jellies can be found in Australia, the Philippines, Hawaii, Vietnam, and many other tropical areas. Box jellyfish are extremely venomous and can kill humans; some marine species (such as turtles) are immune to the venom, and are known to feed on the jellyfish.
Box jellyfish are best known for the extremely powerful venom possessed by some of their species. The Chironex fleckeri and the Carukia barnesi (Irukandji) species are amongst the most venomous creatures in the world. Stings from such species are excruciatingly painful, either initially or as an after-effect, and are often fatal to their prey and sometimes even for humans. However, not all species of Box Jellyfish are this dangerous to humans
2. King Cobra
The King Cobra (Ophiophagus hannah) is the world’s longest venomous snake, with a length that can be as large as 6.7 m (22 ft). This species is widespread throughout Southeast Asia and parts of India, but found mostly in forested areas. Its genus name, Ophiophagus, literally means “snake-eater”, and its diet primarily consists of other snakes, including sizeable pythons and even smaller members of its own species. The venom of the King Cobra is primarily neurotoxic, and the snake is fully capable of killing a human with a single bite. The mortality rate from a bite can be as high as 75%. The King Cobra’s venom, which is composed mostly of proteins and polypeptides, is produced in specialized salivary glands (as is the case with all venomous reptiles) just behind the animal’s eyes.
When biting its prey, venom is forced through the snake’s half-inch (1.25 cm) fangs and into the wound. Although its venom is not the most toxic one, a King Cobra’s size enables it to inject larger quantities of venom than most other species. On a single bite, it injects as much as 6 to 7 ml of venom. The large amount of venom in a single bite allows the King Cobra to kill faster and to kill larger animals than other serpents. The King Cobra can kill up to five times faster than the black mamba, so it just takes a few minutes to kill a human, and it can even kill an Asian Elephant within three hours if the larger animal is bitten in a vulnerable area such as the trunk.
3. Marbled Cone Snail
This little beautiful looking Marbled Cone snail can be as deadly as any other animal on this list. One drop of its venom is so powerful that it can kill more than 20 humans. If you ever happen to be in warm salt water environment (where these snails are often found) and see it, don’t even think of picking it up. Of course, the true purpose of its venom is to catch its prey.
Symptoms of a cone snail sting can start immediately or can be delayed in onset for days. It results in intense pain, swelling, numbness and tingling. Severe cases involve muscle paralysis, vision changes and breathing failure. There is no antivenom. However, only about 30 human deaths have been recorded from cone snail envenomation.
4. Blue-Ringed Octopus
The blue-ringed octopuses (genus Hapalochlaena) are three (or perhaps 4) octopus species that live in tide pools in the Pacific Ocean, from Japan to Australia. Despite their small size and relatively docile nature, they are currently recognized as one of the world’s most venomous animals. They are recognized by their characteristic blue and black rings and yellowish skin.
The octopus produces venom that contains tetrodotoxin, 5-hydroxytryptamine, hyaluronidase, tyramine, histamine, tryptamine, octopamine, taurine, acetylcholine, and dopamine. The major neurotoxin component of blue-ringed octopus venom was originally known as maculotoxin, but was later found to be identical to tetrodotoxin, a neurotoxin which is also found in pufferfish and cone snails. Tetrodotoxin blocks sodium channels, causing motor paralysis and sometimes respiratory arrest leading to cardiac arrest due to a lack of oxygen. The toxin is created by bacteria in the salivary glands of the octopus.
5. Death Stalker Scorpion
The deathstalker (Leiurus quinquestriatus), is a species of scorpion, a member of the Buthidae family. It is also known as Omdurman scorpion, Israeli desert scorpion and numerous other colloquial names, which generally originate from the commercial captive trade of the animal. To eliminate confusion, especially with potentially dangerous species, the scientific name is normally used to refer to them. The name Leiurus quinquestriatus roughly translates into English as “five-striped smooth-tail”.
Other species of the genus Leiurus are often referred to as “deathstalkers” as well. It is straw yellow in color, and can grow 3.5 to 4.5 inches (9 to 11.5 cm) in length. As can be seen from the photograph, it is comparatively lightly built compared to other scorpions, with a long thin tail and slender pedipalps. Note that the dark segment on the tail is sometimes faint or even missing, which can complicate identification.]
6. Stonefish
Synanceia is a genus of fish of the family Synanceiidae, the Stonefishes, whose members are venomous and dangerous and/or fatal to humans. They are found in the coastal regions of Indo-Pacific oceans. They are primarily marine, though some species are known to live in rivers. Its species have potent neurotoxins secreted from glands at the base of their needle-like dorsal fin spines which stick up when disturbed or threatened.
The vernacular name of the species, the stonefish, derives from being able to camouflage and transform itself to a gray and mottled color as similar to the color of a stone. The type species of the genus is Synanceia verrucosa, and it includes the species Synanceia horrida that Linnaeus described as Scorpaena. The authors of Synanceia are Marcus Elieser Bloch and Johann Gottlob Schneider in the latters republication of Systema Ichthyologiae iconibus cx illustratum (Illustrated catalog of Fishes), in 1801. The description was accompanied by an illustration by J. F. Hennig. The misspelling Synanceja is regarded as a synonym for this genus
7. Brazilian Wandering Spider
The Brazilian wandering spiders or (Phoneutria spp.), armed spiders (”aranhas armadeiras”, as they are known in Portuguese) or banana spiders (not to be confused with the relatively harmless species of the genus Nephila) are a genus of aggressive and highly venomous spiders found in tropical South and Central America. These spiders are members of the Ctenidae family of wandering spiders. The Brazilian wandering spiders appear in Guinness World Records 2007 as the world’s most venomous spider, and are considered to be responsible for the most human deaths due to envenomation from spider bites.
The Brazilian wandering spiders can grow to have a leg span of up to 10–13 cm (4–5 in). Their body length ranges from 17 to 48 mm (0.7–1.9 in).The genus is distinguished from other related genera such as Ctenus by the presence of dense prolateral scopulae on the pedipalp tibiae and tarsi in both sexes. Phoneutria are especially easily confused with Cupiennius, in which some species also have red hairs on the chelicerae. The wandering spiders are so-called because they wander the jungle floor at night, rather than residing in a lair or maintaining a web. During the day they hide inside termite mounds, under fallen logs and rocks, and in banana plants and bromeliads. P. nigriventer is known to hide in dark and moist places in or near human dwellings
8. Inland Taipan
The Inland Taipan is dark tan, ranging from a rich, dark hue to a brownish olive-green, depending on season. Its back, sides and tail may be different shades of brown and grey, with many scales having a wide blackish edge. These dark-marked scales occur in diagonal rows so that the marks align to form broken chevrons of variable length that are inclined backward and downward. The lowermost lateral scales often have an anterior yellow edge.
The dorsal scales are smooth and without keels. The round-snouted head and neck are usually noticeably darker than the body (glossy black in winter, dark brown in summer), the darker colour allowing the snake to heat itself while only exposing a smaller portion of the body at the burrow entrance. The eye is of average size with a blackish brown iris and without a noticeable coloured rim around the pupil. It has twenty-three rows of mid-body scales, between fifty-five and seventy divided subcaudal scales, and one anal scale. The Inland Taipan averages approximately one metre eighty (six feet) in length, although larger specimens can reach lengths of two meters (six feet eight inches).
9. Poison Dart Frog
Poison dart frog (also dart-poison frog, poison frog or formerly poison arrow frog) is the common name of a group of frogs in the family Dendrobatidae which are native to Central and South America. Unlike most frogs, species are active during the day, and often exhibit brightly-colored bodies. Although all dendrobatids are at least somewhat toxic in the wild, levels of toxicity vary considerably from one species to the next, and from one population to another.
Many species are critically endangered. These amphibians are often called “dart frogs” due to indigenous Amerindians’ use of their toxic secretions to poison the tips of blowdarts. In fact, of over 175 species, only three have been documented as being used for this purpose (curare plants are more commonly used), and none come from the Dendrobates genus, which is most characterized by the brilliant color and complex patterns of its members.
10. Puffer Fish
Tetraodontidae is a family of primarily marine and estuarine fish. The family includes many familiar species which are variously called puffers, balloonfish, blowfish, bubblefish, globefish, swellfish, toadfish, and toadies. They are morphologically similar to the closely related porcupinefish, which have large conspicuous spines (unlike the small, almost sandpaper-like spines of Tetraodontidae). The scientific name, Tetraodontidae, refers to the four large teeth, fused into an upper and lower plate, which are used for crushing the shells of crustaceans and mollusks, and red worms, their natural prey.
Puffer fish are the second most poisonous vertebrate in the world, the first being a Golden Poison Frog. The skin and certain internal organs of many tetraodontidae are highly toxic to humans, but nevertheless the meat of some species is considered a delicacy in both Japan (as fugu) and Korea (as bok-uh). If one is caught while fishing, it is recommended that thick gloves are worn to avoid poisoning and getting bitten when removing the hook.
The tetraodontidae contains at least 121 species of puffers in 19 genera. They are most diverse in the tropics and relatively uncommon in the temperate zone and completely absent from cold waters. They are typically small to medium in size, although a few species can reach lengths of 100 centimetres (39 in)