Nearly all cephalopods are venomous, says study

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Blue-ringed octopuses (Hapalochlaena spp.

) were long thought to be the only venomous cephalopods - not anymore.

A paper by Bryan Fry, Kim Roelants and Janette Norman published in a recent issue of the Journal of Molecular Evolution has revealed that almost all cephalopods (save for some squid) are venomous.

Although the blue-ringed octopuses remained the only group whose venom is dangerous to humans, many other cephalopods were found to possess venom that they use to immobilize their invertebrate prey.

The authors analysed the genes for venom production (by studying their complementary DNA) from different species of cephalopods and found that a venomous ancestor produced one set of venom proteins that over time, had evolved additional proteins to be added to the chemical arsenal.

The authors also studied the venom-producing genes in other animal groups and found that cephalopods and vertebrates have evolutionarily converged in using some of the same venom proteins.

This discovery may help us understand how venom proteins function and facilitate the design of drugs for treating pain, allergies and cancer.

For more information, see the paper: Fry, BG, K Roelants and JA Norman (2009) Tentacles of venom: toxic protein convergence in the Kingdom Animalia. Journal of Molecular Evolution 68, pp. 311"321.