The 8 Most Dangerous Animals In Puerto Rico

With enchanting destinations such as San Juan, Vieques, and the El Yunque National Forest, Puerto Rico continues to be a popular destination for tourists from across the globe. Close to four-million tourists visit the island, on average, annually.

Countless diverse species call Puerto Rico home, such as captivating frogs, birds, and sea turtles. Nevertheless, there are still dangerous animals that tourists and residents alike should be cautious of.

Here are eight of the most dangerous animals in Puerto Rico.

1. Puerto Rican Racer Snake

Scientific Name: Borikenophis portoricensis
Classification: Reptilia
Habitat: Coastal plains, elevated forests
Diet: Carnivores

The Puerto Rican Racer snake has been detected throughout the mainland, especially in the Toro Negro State Forest and El Yunque National Forest. The snakes are native to the island of Puerto Rico.

The Puerto Rican racer snake has an increased chance of coming into contact with humans due to its daily (daytime) hunting activities and is the second largest snake found in Puerto Rico.

The venomous snakes do not commonly strike out at humans but may bite if agitated or threatened. The most common symptoms of a Puerto Rican racer snake bite are localized, including pain and ecchymosis. 

Localized symptoms generally resolved themselves within a week or two following the bite. More severe, systemic symptoms of a Puerto Rican racer snake are nausea, vomiting, edema, and cellulitis.

2. Red Lionfish

Scientific Name: Pterois volitans
Classification: Actinopterygii
Habitat: Coral reefs, warm waters
Diet: Carnivores

The red lionfish has been seen throughout every region of Puerto Rico and is the only lionfish species found in Puerto Rico.

High populations of red lionfish have been recorded in Crash Boat, El Natural, Rincon, Cabo Rojo, and Caja de Muertos and predominantly reside amongst coral reefs.

Red lionfish are not thought to have an aggressive demeanor, but they have the potential to sting humans that may end up too close for comfort. In addition, their sharp spines can penetrate human skin to release a poisonous neuromuscular toxin.

Symptoms of a red lionfish sting can vary in severity based on how profound the sting is on the skin. The first few symptoms of a bite are normally swelling, redness, bleeding, bruising, and a painful sensation.

An anaphylaxis shock may occur for the unlucky few that may be allergic to the venom released by a lionfish sting. Other severe symptoms following a sting include fevers, cardiac arrests, facial swelling, fainting, nausea, and headaches.

See also  Can Grizzly Bears Climb Trees? [Answer & Facts]

There have not been any confirmed fatalities associated with a red lionfish sting. Nevertheless, the sharp spines of these fish may undoubtedly hurt!

3. Giant Centipede

Scientific Name: Scolopendra gigantea
Classification: Chilopoda
Habitat: Tropical forests, subtropical forests
Diet: Carnivores

Giant centipedes are obviously known for their size, growing to be as long as one foot! They are found throughout South America, Puerto Rico, and Jamaica. 

Giant centipedes can thrive in moist and dry environments. While the giant centipede is not a particularly aggressive insect, it may sting its victims through its sharp forcipules if provoked.

Furthermore, centipedes are essentially blind, making it potentially easier to threaten them.

The pointy forcipules of a giant centipede can do significant damage. As they sting their victim, they release venom into humans. There have even been fatalities associated with stings from giant centipedes.

The carnivorous insects can paralyze other insects and reptiles due to their venom’s neurotoxin, Ssm Spooky Toxin (SsTx).

Common symptoms of an excellent centipede sting are nausea, chills, and fevers. Localized symptoms may also occur, including intense pain, swelling, and redness. 

More severe reactions to a sting may also occur, resulting in anaphylaxis and heart palpitations. It is rare for a giant centipede sting to cause acute symptoms.

4. Moon Jellyfish

Scientific Name: Aurelia aurita
Classification: Scyphozoa
Habitat: Warm and tropical waters
Diet: Carnivores

Moon jellyfish are incredibly prevalent in the waters of Puerto Rico. These jellyfish can typically be identified by four purple circular shapes present on them.

They prefer to float through shallower waters, usually near the coast.

Considering they have high populations in Puerto Rico, it is lucky that moon jellyfish cannot “truly” sting human skin. This is because they lack the ability for their sting to puncture human skin.

However, moon jellyfish can still sting the surface of their victim’s skin.

Moon jellyfish are usually regarded to be harmless. Most symptoms that may arise from a moon jellyfish sting are mild (predominantly localized and not systemic).

Frequent symptoms of a moon jellyfish sting are a mildly painful sensation where the sting occurred, in addition to itchiness, redness, and swelling.

While a sting from a moon jellyfish will more than likely not critically injure you, the localized symptoms may surely be an annoyance in your day.

5. Caimans

Scientific Name: Caiman crocodilus
Classification: Reptilia
Habitat: Freshwater, rivers, mangroves, swamps, lakes, marshes
Diet: Carnivores

See also  17 Types Of Animals Like Dolphins (w/ Pictures)

Do not mistake these giant reptiles for alligators! Puerto Rico’s caiman population has thrived throughout the years.

The majority of the caiman population resides throughout the northern coast of Puerto Rico. Its population is thought to be over one thousand.

Caimans have been known to attack humans, especially if they feel provoked or threatened in some way. Several Puerto Rican residents have even reported caimans randomly entering their yards or homes!

At least forty caiman attacks have been recorded over the last several years, several of which were fatal. 

Caimans have sharper teeth than alligators do. Caiman attacks can lead to significant blood loss for its victims, as the reptiles’ razor-sharp teeth can tear through human skin.

Attacks can result in severe lacerations and even bone fractures.

Aside from their alarming set of teeth, caimans may also drown their prey underwater. Once caimans have a firm latch upon their prey (usually holding onto their head or legs), they will keep them underwater.

Without prompt medical attention and antibiotics, wounds from a caiman attack can later become infected. This is primarily due to bacteria entering the wounds from the teeth of a caiman.

6. Mosquitos

Scientific Name: Culicidae
Classification: Insecta
Habitat: Areas of tall grasses, marshes, forests
Diet: Omnivores

Mosquitos thrive in Puerto Rico’s tropical environment. In fact, these pesty insects are active throughout the year (though they are especially active in the summertime).

Mosquitos prefer to populate in humid areas with lower elevations. This makes rivers, lakes, and forests very appealing to the species.

Puerto Rico hosts various species of mosquitos, the most prevalent being Culex and Aedes.

Mosquitos pose a severe threat to humans due to the transmission of grim diseases such as malaria, West Nile, and Zika virus. The insects can easily transmit diseases while sucking on human blood.

Shockingly enough, mosquitos are linked to the highest human fatalities at over one million deaths annually. Most mosquito-related fatalities are from malaria.

The majority of mosquito bites do not lead to severe symptoms or illnesses.

Most bites will solely cause localized symptoms such as pain, redness, and itchiness. More severe reactions to a mosquito bite can result in a rash comparable to hives.

After being bitten by a mosquito, beware of the symptoms of malaria. Malaria symptoms can be similar to flu symptoms, such as fatigue, headaches, chills, and muscle aches.

7. Great White Shark

Scientific Name: Carcharodon carcharias
Classification: Chondrichthyes
Habitat: Coastal waters, deeper oceanic waters
Diet: Carnivores

Though there have been few reported spottings of great white sharks swarming Puerto Rican waters, it wouldn’t hurt to keep an eye out for these deadly sea creatures.

See also  16 Animals with Fangs

Great whites are often regarded as the most dangerous shark due to their ability to injure significantly or even kill humans they attack.

These sharks are massive in size, with records of great whites being up to six meters in length and weighing 3,000 kilograms.

Apart from their intimidating size, great whites are speedy swimmers; their agility allows them to quickly hunt down, wound, and kill their prey. Fortunately, great whites do not generally act aggressively.

While Puerto Rico’s waters are unlikely to be heavily populated with great whites, attacks from these sharks are serious. 

350 great white attacks have been reported since 1958, according to the International Shark Attack File. Fifty-nine of these attacks resulted in fatalities, and great whites frequently mistake humans for oceanic prey, causing them to attack.

Attacks from a great white can result in traumatic blood loss. Their incredibly sharp teeth inhibit the sharks from shredding through flesh.

In severe cases, victims can even lose limbs or their life. Another threat for shark attack victims is an infection of the wound following an attack.

8. Sand Fleas

Scientific Name: Tunga penetrans
Classification: Insecta
Habitat: Tropical and subtropical environments
Diet: Carnivores

Sand fleas can be spotted crawling the beaches of many Caribbean islands, including Puerto Rico. Sand fleas are also known as sand flies due to their flying abilities.

At night, these pesky insects are particularly active. Throughout daytime hours, sand fleas usually submerge themselves in the sand.

Sand fleas will bite humans, but the bite from a female poses a much more severe threat. The insects bite when they are hungry, sucking the blood from their human, similar to a mosquito.

Beachgoers should beware; sand fleas frequently bite those sunbathing or walking on the beach.

The predominant issue related to sand flea bites is an infection known as tungiasis. Tungiasis is a condition of the skin that results from infection. 

As a female sand flea bites, she may lay eggs in the skin of her victim. Symptoms of tungiasis are pain, itching, and abscesses. Symptoms may even lead to tissue necrosis.

Apart from developing tungiasis, sand flea bite symptoms may be localized or systemic. Localized bite symptoms are minute bumps, redness, itchiness, and inflammation.

These symptoms usually resolve themselves within several days following a bite.


Puerto Rico hosts many dangerous species, from sharks to snakes to sand fleas. Not to worry, most of these species will not attack people unless provoked or threatened.

Claudia Bensimoun

Claudia Bensimoun is a writer who specializes in veterinary topics. Aside from writing for Wildlife Boss, Claudia also writes for other major blogs like Fido Friendly, Animal Wellness Magazine, and the United States Dog Agility Association (USDAA). She has ghostwritten over 50 different e-books. Her passions include animal welfare, veterinary research, and wildlife conservation.

Recent Posts