Venom

Venom is a type of toxin produced by an animal that is delivered through a bite, sting, or similar action using special structures like fangs or a stinger. This process is called envenomation. Unlike poison, which is absorbed through the skin or eaten, venom is actively injected into another creature.

Venom has evolved in many different animals, both on land and in water, including predators and invertebrates. These toxins work in several ways, such as killing cells, affecting nerves, damaging muscles, or disrupting blood clotting. Despite the danger they pose, venomous animals cause many human deaths each year.

Scientists study venoms because they can help treat serious medical conditions like thrombosis, arthritis, and some cancers. Research in venomics is exploring even more ways that these toxins might be used to improve human health.

Evolution

Further information: Evolution of snake venom

Venom is found in many different animals, showing how similar traits can develop in unrelated species. This is called convergent evolution. Venom has evolved independently at least 104 times in animals across 8 groups. The genes that make these toxins are specially chosen, leading to many different types of venom with specific jobs.

Some animals can even get venom toxins from tiny organisms, like microbes, that live in their venom organs. Venoms change over time to work best against the animals they usually hunt, often targeting specific parts inside their prey.

Mechanisms

Main article: Toxin

Venoms are made up of many toxins that can affect the body in different ways. One type is neurotoxins, which mainly impact the nervous system and are found in animals like mambas, black widow spiders, scorpions, box jellyfish, cone snails, centipedes, and blue-ringed octopuses. Another type is myotoxins, which damage muscles and are present in snake and lizard venoms, such as that of rattlesnakes. Cytotoxins are toxins that kill individual cells and are found in the venom of honey bees and black widow spiders.

Taxonomic range

Venom is found in many different animals, both insects and vertebrates, living in water and on land. Some spiders, like spiders, use fangs to inject venom, while scorpions and bees use stingers. Even some fish, like stingrays and sharks, have venom.

Some snakes, such as the prairie rattlesnake, produce venom in special glands and deliver it through fangs. Other venomous animals include the Mexican beaded lizard, gila monster, and even some mammals like vampire bats and platypuses. Venom helps these animals catch prey or defend themselves.

Venom and humans

Venoms from animals like snakes and Gila monsters have been studied for their potential to help treat many diseases. Scientists have looked at over 5,000 papers to see how these venoms might be used in medicine.

In healthcare, proteins from snake venom are used to treat conditions such as thrombosis, arthritis, and certain cancers. The venom of the Gila monster includes a substance called exenatide, which helps people with type 2 diabetes. Compounds from fire ant venom are also being explored for treating diseases like cancer and psoriasis. A field called venomics studies the proteins in venoms to find new ways to use them in medicine.

Main article: Envenomation

Resistance

Further information: Antipredator adaptations

The California ground squirrel is resistant to the Northern Pacific rattlesnake's venom. Many predators use venom to catch their food, and over time, their prey have developed resistance to this venom. This back-and-forth is called a chemical arms race.

The kingsnakes of the Americas can eat venomous snakes without being harmed by their venom. Among marine animals, eels are resistant to the venom of sea snakes. Clownfish live among the tentacles of venomous sea anemones and are resistant to their stings due to a special protective mucus.

Non-animal venoms

Venoms are not just found in animals; many different types of living things can produce and deliver toxins. For example, certain bacteria, like Pseudomonas aeruginosa, have special systems that can inject harmful substances into other cells. Stinging plants also deliver toxins to affect their targets, and some fungi can penetrate other organisms to release toxins that kill cells. Even some tiny organisms called protists have special structures to inject toxins into their prey.