One of the world’s most deadly spiders may have developed its extremely toxic venom as a way of protecting itself while on its annual sex march.
The venom of Australian funnel-web spiders contains delta-hexatoxins, which are the peptides that makes the venom dangerous for humans and primates. There have been 13 recorded deaths, though none since antivenoms became available in the 1980s. It is estimated 30 to 40 people are bitten every year.
The venom attacks the nervous system, blocking nerve impulses to the muscles and causing paralysis of the entire nervous system. This leads to a range of symptoms including muscular twitching, breathing difficulty, fast pulse and increased blood pressure, among others.
….The findings showed the funnel-web spider venom originally evolved to target insects, including flies and cockroaches. However, it appears natural selection led it to change to become a vertebrate-specific defensive venom. “The toxicity to humans, the team said, was just an “evolutionary coincidence.”
“Unluckily for us, we’re a vertebrate species which copped it in the process,” Fry said.