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.

Yellow-tan scorpion 6–7 cm with thin tail. One of the most medically important species in central and southern Mexico — Morelos, Guerrero, Michoacán.

Highly potent neurotoxin. Combined with C. tecomanus, responsible for the highest scorpion mortality in Mexico's Pacific states. Antivenom widely deployed.

Tropical and subtropical zones of Morelos, Guerrero, Michoacán, Mexico State, Puebla. Common in rural homes.

Nocturnal. Hides under bark, stones, in cracks of adobe walls. Aggressive when cornered — can sting through thin clothing.

Up to 1.8 m. Unlike most rattlesnakes, has potent neurotoxic venom (similar to mamba). Common in dry interior valleys of Central America.

Neurotoxin causes paralysis and respiratory failure — different symptoms than US rattlers. Antivenom essential within hours.

Dry tropical forests, savannas, and farmland of Mexico (Yucatán), Guatemala, Belize, Honduras, El Salvador, Nicaragua, Costa Rica.

Nocturnal in hot weather. Often found near villages and in agricultural areas. Causes most snakebite deaths in Costa Rican Pacific lowlands.

Brightly banded red-yellow-black snake up to 1.2 m. Related to cobras and mambas — the only elapid in eastern North America. "Red touch yellow, kill a fellow."

Powerful neurotoxin can cause respiratory paralysis. Bites rare — only ~25 per year in US — but require antivenom (which is increasingly scarce).

Pine flatwoods, scrub oak, leaf litter of Florida, Georgia, Alabama, Mississippi, Louisiana, parts of Texas and northern Mexico.

Secretive and reluctant to bite — must chew to inject venom. Often confused with non-venomous milk snake.

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.

Up to 5 m. Greenish-grey with narrow, V-shaped snout. Found in saltwater and brackish coastal areas — unique among crocs in tolerating both fresh and saltwater.

More dangerous than American alligator. Several fatal attacks per year in Mexico, Central America, and Caribbean. Ambushes from water.

Coastal mangroves, estuaries, lagoons of southern Florida, Mexico, Belize, Guatemala, Honduras, Costa Rica, Panama, Cuba, Hispaniola, and northern South America.

Less docile than alligator. Excellent saltwater swimmer — has crossed 100+ km of open ocean. Active at night.

Stocky, aggressive shark up to 3.5 m. Uniquely tolerant of fresh water — found in Mississippi, Amazon, even Lake Nicaragua.

Top contender for most dangerous shark to humans. Hunts in shallow, murky water — exactly where people swim. Many attacks attributed to 'great whites' are actually bull sharks.

Shallow coastal waters, estuaries, rivers — Florida, Gulf of Mexico, Caribbean (Cuba, Bahamas, DR), Lake Nicaragua, Mississippi River, Pacific coasts of Mexico and Central America.

Aggressive and territorial. Tolerates salinity from 0 to 53 ppt. Attacks unprovoked more than other sharks.

Dark brown bug 2 cm long with red-orange edges. Bites face at night (hence 'kissing') while you sleep. Transmits Chagas disease — a chronic illness affecting heart and digestive system.

About 300,000 people in US infected with Chagas (mostly immigrants). 30% develop fatal heart damage decades later. Vector range expanding north with climate change.

Wood-rat dens, log piles, dog kennels of southern US (Texas to Georgia), all of Mexico, Central America.

Active at night. Defecates near bite site — parasites enter through bite wound or rubbed-in feces.

Small (up to 80 cm), brilliantly colored pit viper — yellow, green, brown, or pink. Famous for raised scales above the eyes resembling eyelashes.

Hemotoxic venom causes severe local damage. Bites are dangerous but rarely fatal due to small size. Often bites pickers and tourists who don't notice it on branches.

Tropical rainforests of southern Mexico, Guatemala, Honduras, Costa Rica, Panama, and northern South America.

Almost entirely arboreal. Hangs from branches and ambushes hummingbirds, lizards, frogs. Hides on banana stalks — picked up with fruit.

Not a jellyfish but a colony. Distinctive blue-purple gas float with 30-metre tentacles trailing below. Drifts onto US Atlantic and Gulf coasts.

Excruciatingly painful sting causing whip-like welts. Rarely lethal, but several deaths recorded from heart failure or drowning after shock.

Atlantic and Gulf coasts — Florida, Texas, Louisiana, North Carolina; sometimes washes up by the thousands.

Drifts on wind via sail-like float. Cannot swim — entirely passive. Tentacles sting for weeks even after death.

'Killer bee' — hybrid of African and European honey bees, escaped Brazilian lab in 1957. Spread north and arrived in southern US in 1990; now in Texas, Arizona, Nevada, California, Florida.

Individual sting like normal bee, but they swarm aggressively — attacking in 100s for minor disturbance, pursuing victims 400 m. About 1–2 deaths per year in US.

Southern US (Texas, Arizona, California, Florida), all of Mexico, Guatemala, Honduras, Nicaragua, El Salvador, Costa Rica, Panama, Belize.

Easily provoked by vibration, sound, dark colors, exhalation. Stays angry for 24+ hours after disturbance.