Two of the World’s Most Venomous Spiders Are Actually Cousins

Two of the World’s Most Venomous Spiders Are Actually Cousins

Have you ever heard those stories of a boy and a girl falling in love only to later discover they are cousins, or even worse, brother and sister? Well, I don’t know how often that actually happens in real life, but in the insect world a similar situation has recently been discovered. Two of the world’s most venomous spiders have been thought to be from completely different families and only very distantly related, but new research has proven that they are actually very closely related cousins on the evolutionary line.

The two spiders in question are the Australian funnel-web spider and the eastern Australian mouse spider. The funnel-web spider is a member of the family Atracinae, Atrax robustus, and is considered by much of the world the most venomous spider on earth. Quite a number of people get bitten by funnel-web spiders every year, but due to the wide availability of antivenom, it is only the rare few that actually die from it. The mouse spider has similarly dangerous venom, but belongs to the Actinopodidae family.

Scientists previously believed that these two spiders separated from one common ancestor 200 million years ago, making them only distantly related. However, based on their anatomy as well as other characteristics, the two types of spider do resemble very closely other spider species that have also typically been thought to be distantly related to them. One group of scientists thought that there may be more to this physical similarity between spiders in the two families, Atracinae and Actinopodidae. The funnel-web and mouse spider also have very similar venom, as the same antivenom can be used to treat both bites. Some scientists began to suspect these spiders might be more closely related than they’d previously believed.

Marshal Hedin, a biologist at San Diego University, along with colleagues and some biologists in New Zealand and Argentina banded together to study these two spiders and see just how closely related they really are. After studying specimens that represented different branches of the spiders that were both closely and distantly related. After sequencing chunks of their genome to look for any genetic similarities, they found that, indeed, the spiders are much more closely related than we’d previously believed. Solving this mystery not only revealed new clues to the evolution and genetics of these spiders but also will help scientists be able to create a more general antivenom to treat bites from many different related spider species rather than just one or a few.

How else do you think this new discovery will affect the scientific world and the study of spiders specifically?