From frogs and toads to butterflies and beetles, there is no shortage of toxicity in the animal kingdom. Read on to discover our list of poisonous animals – some you may know well, others may surprise you.

By Leoma Williams

Published: Friday, 12 July 2024 at 15:33 PM


It’s a tough world out there and many animals have had to arm themselves. One capacity that has evolved time and time again is toxic weaponry – venoms and poisons.

Although oft confused, there is a clear distinction between these two forms of toxins. Whereas venoms are produced in specialised tissues and are delivered to predators or prey through specialised body parts such as fangs and stingers, poisons are not directly delivered. They are instead accumulated within an animal’s tissues and exert their effects when the animal is touched or consumed. Poisoning is often passive, whereas envenomation is an active process.

As you will see from our list of most poisonous animals, many of these toxins are acquired through the poisonous animal’s own diet and most are used as a defence mechanism against predators. There are some, however, such as the Greenland shark, in which their toxicity is merely a by-product of other adaptations to their environment. Read on to find out more!

10 poisonous animals

Poison dart frog (Dendrobatidae family)

Strawberry Poison Dart Frog in Costa Rica. © Christian Sanchez/500px/Getty

Starting off with a zoo staple, it’s the legendary poison dart frog. These tiny amphibians pack a big punch, with the deadliest of the family (the golden poison dart frog) having enough venom to kill ten grown men! It is considered to be among the most toxic animals on earth. Not bad for a 2-inch-long bright yellow frog.

The weirdest frogs in the world, from ultrasonic screamers to the bizarrely hairy. There’s even a frog that can fly…

Poison dart frogs derive their toxins from their food, including mites, centipedes and ants, in a process known as diet toxicity. It functions as a chemical defence against any predator who might be unwitting enough to eat them. To make sure this rarely happens they have evolved a bright warning colouration alongside their toxins, telling predators to stay away. This advertisement of “I’m bad to eat” is known as aposematic colouration.

Cane toad (Rhinella marina)

A bloated Australian cane toad, showing its poisonous milky secretion. © Getty

From little frogs to large toads, the next on our list is a very troublesome species indeed. Cane toads, native to South and Central America but introduced to many other countries, are considered to be one of the worst invasive species in the world.

They are a particular problem in Australia where they were introduced to eat sugar cane beetles but spent more time voraciously reproducing and having a terribly negative impact on the native wildlife. Their toxicity plays a part in this. They secrete bufotoxin, a milky poison, from glands in their skin when threatened.

In their native habitats, many predators have evolved ways to combat this defence mechanism, but this is not so in Australia where they are an alien species. This means that they have no natural predators and so can multiply rapidly and potentially kill any animal that tries to eat them!

Read about some of the UK’s troublesome invasive species

Pfeffer’s flamboyant cuttlefish (Metasepia pfefferi)

Flamboyant cuttlefish (Metasepia pfefferi) at Kapalai House Reef in Malaysia. © Andre Seale/VW PICS/Universal Images Group via Getty Images

This colourfully named cephalopod is another species that is thought to utilise aposematic colouration. At rest, it is a dark brown, but when faced with a predator it will quickly change colour, creating a vibrant moving display of black, white, and yellow, with bright red arm-tips.

And the warning it is giving off is genuine, it really wouldn’t be profitable to eat, due to its highly toxic muscle tissue. The toxins it contains are in fact so potent that it is thought to rival the notorious blue-ringed octopus, one of the most dangerous animals in the ocean.

The cuttlefish, thanks to its ability to change colour, made it onto our list of the weirdest fish in the world.

Greenland shark (Somniosus microcephalus)