Summary
Toxins evolved repeatedly from ordinary proteins in snakes, spiders, cone snails and others.
In depth
Toxins in snakes, scorpions, cone snails and platypus arose from gene duplication and recruitment of ordinary body proteins. Neurotoxins disrupt ion channels; haemotoxins affect blood. Venom components are drug leads.
Venom genes duplicate and diversify quickly. Resistance evolves in prey and predators. Venom use has evolved for defence and predation.
Key idea: toxins are recruited from normal body proteins.
Venom has evolved independently over 100 times in animals. Components include neurotoxins, haemotoxins, cytotoxins and enzymes. Gene duplication and neofunctionalisation of genes with other roles (digestive enzymes, hormones, immune proteins) explain how toxins arise, and snakes recruited proteins such as phospholipase A2 and three-finger toxins. Venom composition varies with diet and geography, and prey may evolve resistance, as in mongooses, opossums and honey badgers with changed receptors, giving an arms race.
Venom is a source of drugs: captopril (from a pit viper), exenatide for diabetes (Gila monster), ziconotide (cone snail) and eptifibatide (rattlesnake). Antivenom is made from antibodies of immunised animals. Venomous animals include snakes, spiders, scorpions, jellyfish, centipedes, shrews and some fish.
Remember: venom is injected (bite or sting), whereas poison is ingested or absorbed.
Frequently asked questions
What is Venom Evolution?
Toxins evolved repeatedly from ordinary proteins in snakes, spiders, cone snails and others.
Which area of biology covers Venom Evolution, and how advanced is it?
Venom Evolution is one of the 53 topics in Zoology & Animal Diversity. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Bioluminescence, Parasitism in Animals, Island Gigantism and Dwarfism.
Can you give an example of Venom Evolution?
Captopril was developed from pit viper venom.
What should I learn before Venom Evolution?
Work through the Beginner topics in Zoology & Animal Diversity first, such as Animal Kingdom, Vertebrates and Invertebrates, Sponges, then return to Venom Evolution. Advanced topics assume the Intermediate vocabulary.
What topics are related to Venom Evolution?
The closest topics to Venom Evolution are Bioluminescence, Parasitism in Animals, Island Gigantism and Dwarfism, Domestication Genetics. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Venom Evolution?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Venom Evolution. To practise the whole of Zoology & Animal Diversity, use the Zoology & Animal Diversity quiz.
How is Venom Evolution different from Bioluminescence?
Venom Evolution: Toxins evolved repeatedly from ordinary proteins in snakes, spiders, cone snails and others. Bioluminescence: Light produced by luciferin and luciferase reactions in deep-sea fish, fireflies and jellyfish. Read both side by side and note what each one explains.
How should I study Venom Evolution step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Bioluminescence and explain the difference aloud. Finally, take the Zoology & Animal Diversity quiz and come back to this page for any question you miss.