Most Dangerous Lizards And Turtles In The World

From snakes to the legendary dinosaurs, reptiles are a notorious subsection of the animal kingdom that has produced some of the most deadly and terrifying creatures to have ever walked the earth. Talons, fangs, whip-like tails, and venoms are all hallmarks of these cold-blooded creatures whose slitted eyes and smooth scaled skin have been the object of repulsion and fear for millennia. Lizards are also among the most diverse subgroups of reptiles, producing everything from the soft and docile totem of Hawaii, the gekko, to some of the most massive and terrifying reptilians to walk the earth since the dinosaurs — monitor lizards, among them the infamous Komodo dragon.

Turtles too, despite being mostly thought of as slow-moving terrarium pets, have produced their fair share of formidable reptile species capable of munching through flesh and bone, and even swarming prey much larger than themselves. Here are some of the most dangerous lizards and turtles that have ever lived, most of which still walk the earth to this day.

Save, perhaps, a certain team of crime-fighting comic book heroes, turtles aren't generally what most people think of when deadly comes to mind. Residents of the southeastern United States, however, know that salmonella isn't the worst everyone's favorite slow-moving underdog can dish out. One of the south's many notoriously hazardous fauna, alligator snapping turtles are a formidable reptile with a prehistoric look, aggressive demeanor, and one of nature's nastiest bites.

Though often exaggerated to have a 1,000-pound bite force, an alligator snapper's bite is actually less than that of the common snapping turtle. At an average of 35.5 pound-force, that's over 250 pound-force less than that of an adult human, as per The Forest Preserve District of Will County. Nonetheless, as reported by ThoughtCo, that's more than enough force to sever fingers, aided in large part by the animal's sharp mandible beak. Additionally, all four of this turtle's limbs sport bear-like claws, which, as Tufts Wildlife Clinic points out, are plenty sharp enough to cause deep gashes. Despite their weaponry, appearance, and nasty reputation, many experts, including the reptile and reptile ecosystem protection non-profit, The Orianne Society, insist that alligator snappers only attack when cornered and provoked. In fact, though not legal everywhere, people have been known to keep alligator snappers as pets.

Until a 2005 research paper concluded otherwise, it was long thought that only three lizard species –- all native to North America — possessed venom: the Mexican and Guatemalan beaded lizards and their larger Northern relative, the gila monster. By far the most notorious of the three, the gila monsters have inspired folk legends for generations, even becoming the subject of a 1950s creature feature wherein a 50-foot version attacks a small Texas town. In truth, the real life monster grows to a more modest 22 inches and weighs 5 pounds, a scale well below most other dangerous lizards. Additionally, despite a reputation that says otherwise, gila monsters rarely attack humans, and, according to the Wilderness Medical Society, no human has died from a gila attack since the 1930s. Nevertheless, you wouldn't want to run into one in a dark desert alley at night.

An old adage claims that, if bitten, a gila monster's jaws will remain firmly clamped until sundown (from the Arizona-Sonora Desert Museum), which, despite poetic exaggeration, is actually somewhat true. Unlike snakes, which inject venom into their victims directly through hollow fangs, gila monster venom drips from glands near their gums, before being essentially chewed into their victims as they maintain a firm and severely painful bite lasting several minutes. And the damage is far from over once the lizard finally releases its bite: As described by the Wilderness Medical Society, envenomation symptoms can approximate a bad flu, along with swelling, drop in blood pressure, and sweating.

According to the Humane Society of the United States, iguanas were once the number one pet reptile in the U.S. While this is no longer the case, thanks in no small part to restrictions and bans such as those enacted by the Florida Fish & Wildlife Conservation Commission, iguanas remain a fairly popular pet within the U.S. and beyond. According to Encyclopedia Britannica, roughly 30 species of iguana exist, and while the species most commonly kept as a pet, the common green iguana, is naturally more docile and tolerant of humans, all iguana species are actually pretty dangerous lizards.

Across the iguana family, that danger mostly comes from being bitten, which aside from being incredibly painful also commonly causes swelling and excessive blood loss. Prior to 2005, popular scientific consensus was that only a handful of lizards were venomous, placing the blame for most adverse reactions to lizard bites squarely on bacterial infections. That year, a team from the University of Melbourne published new findings indicating that, in fact, most large lizard species produce venom and were capable of inducing mild envenomation in humans (via New Scientist). Additionally, as a mostly arboreal (tree climbing) animal, many iguanas also come equipped with sharp claws on all four feet. While these are no more (or less) sharp than those of a house cat, iguanas naturally carry salmonella, which can become transferred via its claws, leading to painful and dangerous bacterial infections (from Reptile Valley).

Along with the closely related and infamous gila monster, Mexican and Guatemalan beaded lizards were once the only lizard species thought to produce venom. While it is now understood that many lizard species produce venom, beaded lizard venom is some of the most deadly. Despite bites being rare, and actual envenomization being even rarer, a 2003 report in the National Library of Medicine details how serious a beaded lizard bite can be. In the report, a 40-year-old man was hospitalized with symptoms of vomiting, dizziness, and severe pain. Shortly after being admitted, the patient was put on oxygen supply before being transferred to intensive care where he spent the next day recovering.

Though no anti-venom exists for any beaded lizard, modern medical practice has dramatically reduced the likelihood of fatality from being bitten by any of these three lizards. And while Animal Diversity Web claims beaded lizards are more aggressive than gila monsters -– especially at night when they tend to hunt and hostile interactions with humans are more likely to occur — all known instances of being bitten in recent history have come as a result of a lizard being handled, or intentionally provoked. Regardless of these caveats, a rare bite could quickly become fatal under the wrong circumstances, so it's best to avoid the possibility of a bad interaction when possible.

Snapping turtles are popularly thought to have the strongest jaws of all turtles, terrapins, and tortoises but are in fact surpassed by a surprising number of their cousins, including the charismatic Loggerhead sea turtle. Found in oceans and seas around the globe, Loggerheads can grow up to4 feet long and weigh as much as 400 pounds. According to the World Wildlife Foundation, they are directly related to a group of turtles that has been around for more than 100 million years. Makes sense that Loggerheads would still be around, since they use their massive heads and incredibly powerful jaw muscles to eat all kinds of crunchy foods, such as clams, sea urchins, and basically any mollusk it can find (via CaliforniaHerps).

In a research article published in the Journal of Experimental Biology in 2012, researchers found that the bite force of Loggerheads was relative to their size. Meaning that, as Loggerheads grow, their bite force grows, allowing them to ingest larger, harder food, which in turn allows them to grow even larger. Larger turtles can have a bite force as strong as 100 pounds-force. Pair that powerful jaw with the Loggerheads much larger size, and it's easy to imagine a finger, or worse, getting chomped off by those unlucky enough to swim into Loggerhead territory on a bad day.

It's no secret that crocodiles are not to be trifled with, so it stands to reason that any animal named after these saltwater terrors would be formidable in its own right as well. While its rounded snout and long tail are the primary reason for the nickname "tree crocodile," there's no denying the crocodile monitor of New Guinea poses its fair level of danger if not handled with care. (Incidentally, the physical similarities with crocs are prevalent enough that the Singapore Government has a breakdown of their differences available via their national park's website.) 

Like other monitor lizards, crocodile monitor lizard's have long, dexterous claws, perfect for climbing into trees. Unlike other monitor lizards, these tree dwellers can often be seen hanging from branches by their powerful back legs, notes Animalia. As with the rest of its family, the crocodile monitor is venomous, meaning a closer interaction could end in a meeting with those sharp, poisoned fangs, and a quick trip to the emergency room.

Though primarily scavengers, crocodile monitors will hunt when necessary, in their own peculiar way. While many predators — including its Komodo cousin — prefer a sneakier, stealthier attack, crocodile monitor lizards prefer to face their prey head on, a move that's sure to be intimidating to anything on the wrong end of it. While this is mostly bad news for birds and small mammals, Animalia reports they've been known to hunt pigs, deer, and even hunting dogs.