7 of the world's most deadliest snakes

They hiss, they slither and unfortunately for humans and unsuspecting prey, they bite. Snakes bite about 5.4 million people every year, resulting in between 81,000 and 138,000 deaths, according to the World Health Organization.

Venomous snakes kill their victims with toxic substances produced in a modified salivary gland that the animal then injects into prey using their fangs. Such venom has evolved over millions of years to cause severe reactions in the victim, from immobilization and hemorrhage to tissue death and inflammation, researchers reported in 2019 in the journal Frontiers of Ecology and Evolution.

Here are snakes whose venom not only packs a punch for small prey but that can take out humans. Get ready to run!

Native to the mountains and grasslands of southeast Australia, the eastern tiger snake (Notechis scutatus) is named for the yellow and black bands on its body, though not all populations sport that pattern, according to the Australian Museum. Its potent venom can cause poisoning in humans in just 15 minutes after a bite and is responsible for at least one death a year on average, the University of Adelaide reported. 

Around 58,000 deaths in India are attributed to snake bites every year, and the Russell's viper (Daboia russelii) is responsible for the majority of these mortalities, according to research published March 25, 2021, in the journal PLOS Neglected Tropical Diseases. This species is considered one of the most deadly of the true vipers, researchers reported in 2021 in the journal Toxins. 

In Sri Lanka, where this nocturnal viper likes to rest in arable fields, they cause high mortality among farmers during harvest time. The snake's venom can lead to an awful smorgasbord of symptoms: acute kidney failure, severe bleeding and multi-organ damage, researchers reported in the Handbook of Clinical Neurology in 2014. Some components of the venom related to coagulation can also lead to acute strokes, and in rare cases, symptoms similar to Sheehan's syndrome in which the pituitary gland stops producing certain hormones. Victims typically die from renal failure, according to the handbook. 

The saw-scaled viper (Echis carinatus) is the smallest member of the "Big Four" in India — along with Russell's viper, the common krait (Bungarus caeruleus) and the Indian cobra (Naja naja) — thought to be responsible for the most bites and related deaths in the country.

Rather than the stereotypical "hissing" sound attributed to snakes, this viper starts "sizzling" by rubbing together special serrated scales when threatened, according to research published in 2013 in the Journal of Venomous Animals and Toxins including Tropical Diseases, according to a journal statement. Once bitten by this viper, a person will have localized swelling and pain in the area, followed by potential hemorrhage. Since the venom messes with a person's ability to clot blood, it can lead to internal bleeding and ultimately acute kidney failure, according to the educational society Understanding Animal Research. Hydration and antivenom (there are nine types of antivenom for this snake) should be administered within hours of the bite for a person to survive, Understanding Animal Research said.

The banded krait (Bungarus fasciatus) is a slow mover during the day and is much more likely to bite after dark. The snake's venom can paralyze muscles and prevent the diaphragm from moving, according to a 2016 study published in the journal PLOS Neglected Tropical Diseases. This stops air from entering the lungs, effectively resulting in suffocation.

The king cobra (Ophiophagus hannah) is the world's longest venomous snake, measuring up to 18 feet (5.4 m), according to the Natural History Museum in London. The snake's impressive eyesight allows it to spot a moving person from nearly 330 feet (100 m) away, according to the Smithsonian Institution. When threatened, a king cobra will use special ribs and muscles in its neck to flare out its "hood" or the skin around its head; these snakes can also lift their heads off the ground about a third of their body length, according to the San Diego Zoo. 

Its claim to fame is not so much the potency of its venom, but rather the amount injected into victims: Each bite delivers about 7 milliliters (about 0.24 fluid ounces) of venom, and the snake tends to attack with three or four bites in quick succession, the Fresno Zoo reported. Even a single bite can kill a human in 15 minutes and an adult elephant in just a few hours, Sean Carroll, molecular biologist at the University of Maryland, wrote in The New York Times.

You could be bitten multiple times before becoming aware of the coastal taipan (Oxyuranus scutellatus), thanks to its incredible speed, according to the Australian Museum. When threatened, this snake, which lives in the wet forests of temperate and tropical coastal regions, will lift its whole body off the ground as it jumps fangs-first with extraordinary precision and injects venom into its enemy. Before 1956, when an effective antivenom was produced, this snake's bite was nearly always fatal, according to Australian Geographic. 

The inland taipan is the one of the most venomous snakes, according to the International Journal of Neuropharmacology, meaning just a teensy bit of its venom can kill prey (or human victims). They live tucked away in the clay crevices of Queensland and South Australia'a floodplains, often within the pre-dug burrows of other animals. Living in more remote locations than the coastal taipan, the inland taipan rarely comes into contact with humans, the Australian Museum reported. When the taipan does feel threatened, the snake coils its body into a tight S-shape before darting out in one quick bite or multiple bites. A main ingredient of this venom, which sets it apart from other species, is the hyaluronidase enzyme. According to a 2020 issue of Toxins journal (Novel Strategies for the Diagnosis and Treatment of Snakebites), this enzyme increases the absorption rate of the toxins throughout the victim's body.