Up to 17 cm leg span. Holds Guinness record for most venomous spider. Brown with banded legs; raises front legs in defense.

Neurotoxin causes intense pain, paralysis, suffocation, and (in 1% of cases) death. About 4,000 bites per year in Brazil alone. Hides in banana shipments — found in Europe and US in shops.

Forests of Brazil, Paraguay, northern Argentina, Uruguay, eastern Bolivia. Wanders at night looking for prey — hence the name.

Doesn't build webs. Active at night. Often hides in bananas, shoes, woodpiles, inside houses. Female aggressively defends egg sac.

Up to 1.8 m. The widest-ranging rattlesnake in South America. Unique among rattlers for highly neurotoxic venom (most have hemotoxic).

Neurotoxin causes paralysis, blindness, kidney failure. Mortality up to 12% without antivenom — much higher than US rattlers. About 1,000 bites/year in Brazil.

Dry savannas, Cerrado, and Caatinga of Brazil, Argentina, Bolivia, Paraguay, Uruguay, Colombia, Venezuela.

Nocturnal in hot weather. Often near villages and farms hunting rodents. Rattles loudly before striking — but doesn't always.

Up to 1.6 m. Brown with darker triangular blotches. Causes more snakebites than any other species in southeast Brazil. Its venom led to the discovery of ACE inhibitors (blood pressure drugs).

Hemotoxic venom causes severe local damage, hemorrhage, kidney failure. About 20,000 bites per year across Brazil, with 0.1–0.5% mortality even with antivenom.

Atlantic forests and grasslands of southeastern Brazil, Paraguay, northern Argentina, Uruguay.

Nocturnal in summer. Often found near rural homes hunting rodents. Females give birth to up to 20 live young.

Heavy-bodied pit viper up to 2.5 m. Responsible for more snakebite deaths in Central America than any other species — "the ultimate pit viper".

Highly potent hemotoxin causes catastrophic tissue damage and bleeding. Without antivenom, mortality reaches 7–9%. Aggressive when cornered.

Lowland forests, plantations, banana fields from southern Mexico through Guatemala, Honduras, Nicaragua, Costa Rica, and Panama.

Active hunter at night; sometimes climbs into low vegetation. Females give birth to up to 80 venomous neonates.

Largest pit viper in the world — up to 3.7 m. Reddish-brown with diamond pattern. Known by Spanish name 'verrugosa' or local 'matabuey' ("ox-killer").

Massive venom yield. Without antivenom, mortality up to 80%. Rare encounters because it lives deep in untouched forest, but bites are catastrophic.

Pristine tropical rainforests of Costa Rica, Panama, and the Amazon basin (Brazil, Colombia, Venezuela, Peru).

Solitary, nocturnal. Lays eggs (unusual for pit vipers — most give live birth). Vibrates tail like rattlesnake when threatened.

Largest predator in the Amazon — up to 6 m and 500 kg. The only crocodilian to actively hunt humans in South America.

Aggressive and territorial. Attacks documented every year in Brazil, Peru, Bolivia. Excellent night hunter using infrared-sensitive eyes. Attacks fishermen pulling nets, swimmers.

Amazon basin — Brazil, Peru, Colombia, Ecuador, Bolivia, Venezuela, Guyana, Suriname, French Guiana. Slow rivers, oxbow lakes, flooded forests.

Apex predator. Hunts at night. Submerges with only nostrils and eyes visible. Capable of taking jaguars and adult capybaras.

Brown spider 8–40 mm with characteristic violin marking. Considered the most dangerous of all recluse spiders worldwide — 'araña de rincón' in Chile.

Cytotoxic venom causes severe necrotic skin lesions ('loxoscelism') that can spread for weeks. Visceral form attacks kidneys — mortality 3–5% in such cases. Hundreds of bites annually in Chile, Peru.

Inside houses across Chile, Peru, Argentina, Uruguay, southern Brazil — behind paintings, in closets, woodpiles, beds.

Reclusive, nocturnal. Bites only when pressed — often in bedding, while dressing, or while moving stored items.

Heaviest snake on Earth — up to 250 kg and 8 m. Olive-green with black blotches. Lives almost entirely in water in the Amazon basin.

Constricts prey then swallows whole — capable of taking deer, capybaras, even caimans. Documented attacks on humans rare but fatal cases recorded. Drowning + crushing is the killing mechanism.

Slow rivers, swamps, and flooded forests of the Amazon basin — Brazil, Colombia, Venezuela, Peru, Bolivia, Ecuador, Guyana, Suriname, French Guiana.

Mostly aquatic — only eyes and nostrils above water. Ambushes prey at the water's edge. Females eat males after mating.

Third-largest cat — up to 100 kg. Spotted rosettes with central dots distinguish it from leopards. In North America found in Mexico and rarely Arizona/New Mexico.

Strongest bite force of any cat — pierces turtle shells and skulls. Attacks on humans rare but occur in Mexican rainforests.

Tropical rainforests of southern Mexico (Chiapas, Yucatán), Belize, Guatemala, Honduras, Nicaragua, Costa Rica, Panama; rare strays into Arizona.

Solitary, mostly nocturnal. Excellent swimmer — hunts caimans, capybaras, deer. Stalks before pouncing.

Small bat (7–9 cm, 25–40 g) that feeds exclusively on blood. Razor-sharp incisors slice skin painlessly; anticoagulant saliva keeps blood flowing.

Top vector of rabies in Latin America — particularly the Amazon. Several outbreaks per year kill dozens. 2005 Brazilian outbreak killed 23. Cattle deaths cost millions.

From Mexico to northern Argentina — caves, hollow trees, abandoned buildings. Most active in Brazil, Peru, Bolivia, Colombia, Ecuador, Venezuela.

Active 30 minutes after sunset. Approaches sleeping victims (humans, cattle) silently. Bite is so light victim doesn't wake — discovered next morning.

Black with red and white markings on abdomen — distinct pattern from other widows. Found in dry northeastern Brazil, the Caatinga and parts of Amazon edges.

Causes 'foneutrismo' — extremely painful bite leading to muscle spasms, sweating, hypertension. Antivenom available; deaths now rare but recovery slow.

Northeastern Brazil (Caatinga and Cerrado), Venezuela, Colombia, the Guianas. Lives in vegetation, palm fronds, holes.

Builds irregular cobwebs in shrubs. Less likely to enter homes than other widows. Bites typically occur during agricultural work.

Glossy black with red hourglass — South American counterpart of the North American black widow. Found across Argentine Pampas, Uruguay, southern Brazil.

Alpha-latrotoxin causes severe muscle cramps, hypertension, sweating. About 1,000 bites per year reported in Argentina alone. Antivenom is widely available and very effective.

Grasslands and pampas of Argentina, Uruguay, southern Brazil, Paraguay. Also found in agricultural areas, woodpiles.

Builds messy tangle webs near the ground. Female bites only when pressed — typically in fields, while harvesting, or while moving objects.

Up to 2 m. Brown with chevron pattern. Known locally in Trinidad as 'Mapepire balsain'. Causes most snakebites in Trinidad and Amazonia.

Hemotoxic venom causes severe local damage and bleeding. About 50 bites per year in Trinidad alone; antivenom available.

Forests, plantations, and farmland of Trinidad, the Amazon basin, Guianas, and northern South America.

Nocturnal. Often found near human settlements. Females give birth to up to 80 live young at once.

Largest centipede on Earth — up to 30 cm. Reddish-brown with yellow legs. Found across northern South America.

Bite injects highly toxic venom causing severe pain, swelling, fever, vomiting. One confirmed death — a 4-year-old child in Venezuela. Hunts bats, lizards, snakes, mice.

Tropical rainforests of Venezuela, Colombia, Brazil, Peru, French Guiana, plus Trinidad. Hides under logs, in caves.

Nocturnal. Hangs from cave ceilings to catch bats mid-flight. Aggressive when handled — bites with venomous front legs.

Smaller cousin of the black caiman — up to 2.5 m. Named for ridge between eyes resembling spectacles. The most widespread crocodilian in South America.

Less dangerous than black caiman but attacks documented, especially during nesting season. Females aggressively defend nests within 5 m radius.

All freshwater systems from southern Mexico through Colombia, Venezuela, Peru, Ecuador, Bolivia, Brazil, Paraguay, French Guiana, Suriname.

More tolerant of dry seasons than black caiman — buries in mud and aestivates. Active mainly at night.

Up to 2 m long. Despite the name, not a true eel — closer to catfish. Generates the most powerful electric discharge of any animal: up to 860 volts.

Single shock can stun a horse. Multiple shocks cause respiratory paralysis and drowning. Documented deaths in Amazonia — fishermen falling into water with eels nearby.

Slow, muddy rivers and floodplains of the Amazon and Orinoco basins — Brazil, Colombia, Venezuela, Peru, Bolivia, Guyana, Suriname.

Mostly nocturnal. Uses weak electric pulses for navigation, strong jolts for hunting and defense. Can leap from water to shock threats.

Up to 33 cm. Red-orange belly, silver flanks, triangular razor-sharp teeth. The 'classic' piranha of Hollywood films.

Reputation as flesh-stripping killers is largely myth. Real attacks on humans occur during dry season when fish are crowded and hungry — bites are nasty but rarely lethal. Hundreds of foot/hand bites yearly.

Amazon, Paraná, and Orinoco river basins — Brazil, Argentina, Paraguay, Uruguay, Bolivia, Peru, Colombia, Venezuela.

Schooling fish. Most aggressive during low water when fish are concentrated. Attracted to blood and thrashing in water.