This spider adapts its venom to the attacks it receives
the hadronyche valida spider, from the tarantula family, would adapt the composition of its venom according to the attacks it undergoes.
Spiders that evolve their venom according to their age or the environmental conditions in which they evolve, the researchers had already seen. But who adapt instantly to the attacks they suffer, never. It is now done with an Australian spider from the tarantula family, with intriguing behavior.
To each spider, its venom, adapted to its prey? It would be too simple ! Australian scientists have just discovered that a species, considered among the most dangerous in the world, would be able to change the composition of its venom according to the situations it is confronted with. This is the conclusion of a study conducted by Dr. Linda Hernandez Duran , at the Australian Institute of Health and Tropical Medicine at James Cook University in Australia.
Only one tarantula species seems to be able to modify its venom in this way
This spider, Hadronyche valida , belongs to a family of tarantulas, the Atracidae , which is found only in Australia. And the ability to modify its venom seems to be specific to it: scientists have looked for it without success in three close species ( Hadronyche infensa, Hadronyche cerberea and Atrax robustus ). " We analyzed their behavior and measured their heart rate by laser to assess their metabolic activity, said Hernandez Duran . We then collected their venom and analyzed it using a mass spectrometer." Conclusion: only the composition of the venom of Hadronyche valida was modified when the scientists subjected the animal to various stresses (small bites with tweezers, breath of air, etc.). In this species "the presence of certain chemical compounds in the venom seems to depend on cardiac activity and the reaction to an attack" confirms the researcher.
Does the animal become more dangerous for all that? Too early to tell, the precise chemical modifications of the venom have yet to be clarified. “ The venoms are all different in the different species of spiders and even sometimes according to sex in the same species, so we cannot say that one is more venomous than another, specifies Sciences et Avenir Christine Rollard , teacher and researcher at the National Museum of Natural History in Paris and author of nearly a hundred publications on spiders. In addition, toxicity can also vary depending on the prey."
The strategy of defense is not that of attack
Still, it's not clear that this ability is an adaptation for more effective attacks. " It is difficult to link the observations of scientists with the behavior of spiders", says Christine Rollard. Indeed, in this experiment, the animals are only placed in a defensive situation. " But spiders can defend themselves with dry bites, that is to say without injecting venom. They mainly use their venom to attack their prey and feed on it." In this case, this species of Hadronyche uses a trap to capture its prey, a kind of sheet web extended by a funnel. The researchers' experience does not allow us to say whether the venom is modified during a real attack.
Evolving on the Earth's surface for 300 million years, spiders are far from having revealed all their evolutionary adaptations, as evidenced by the recent discovery of species that " hear with their legs " or those that can stay longer . 30 minutes underwater .
By Juliette Legros
Source: websites