What can a spider who has a keen palate do to stop eating its usual heavy diet of insects? Perhaps a few bites of fresh snake could be enough to get the job done. According to a paper in the American Journal of Arachnology, certain species of spiders can eat snakes occasionally. The paper includes many photos to support it.Although scientists believed spiders ate only live insects and other arthropods, recent research shows that their diets are much more varied. Martin Nyffeler, an arachnologist from the University of Basel, and J. Whitfield Gibbons, a University of Georgia herpetologist, said that spiders eat a variety of prey, including earthworms and bristle worms. Multiple cases have been reported of spiders feeding on baby or juvenile snakes, often overpowering them.Nyffeler, Gibbons, and others decided to do the first synthesis. They analyzed published reports, Google photos, Google books and social media sites as well as relevant academic dissertations. The team eventually found 319 reports of spiders preying upon snakes. Most of these were natural incidents. However, about seven percent of the reports were either laboratory feeding trials or field experiments. Nearly 80 percent included photos or videos that documented the horrific acts for posterity.AdvertisementThe authors discovered that 30 of the more than 49,000 species of spiders are known to be able to eat them in the wild. They also found 11 species that have been proven to eat them in captivity. Half of all cases were widow spiders (exclusively females), belonging to the Theridiid species. Some of these spiders are "expert snake catchers," including the Australian feedback spider and the African button spider. There were also four North American species. Tarantulas (Theraphosidae) are the second most frequent spider family that feeds on snakes. These spiders hunt them on the ground or in trees. The third most common target for snakes are large orb-weaving Spiders (Araneidae, Nephilidae)These three spider families account for 80 percent all cases of snake-feeding reported to date. The documented serpentine cases involved 86 species from seven families. Five additional species were involved in captivity, or in staged incidents. They included crayfish snakes and garter snakes as well as king snakes and ringneck snakes.Daniel R. CrookGeorge PopescuTrisha HaasLawrence L.C. JonesKevin Moore/Australian MuseumOri SegevRick WestKarll Cavalcante PintoSilvano Lopex & Danniella SherwoodSalvaddor Contreras - ArquietaEleanor Spice RiceTim AkimoffMax Roberets/iNaturalist CC BY -NCMax Roberets/iNaturalist CC BY -NCDifferent spider families kill their snake-y prey differently. Black widows, for example, rely on the strength and durability of their webs to trap the snake within the web's viscid threads. To release the neurotoxin, the widow will wrap the snake in sticky silk and bite it several times. After the snake is immobilized, the widow will raise the prey from the ground. This can take several hours and allow the snake to eat at her leisure.AdvertisementAlthough tarantulas do not spin webs, their bites can deliver a strong neurotoxin venom to quickly immobilize snakes. According to a 1926 report, a tarantula would grab a snake's head and bite it. The snake will try to get away from the tarantula. The venom kicks in and the tarantula crushes the snake, sucking out all its soft parts. This leaves behind a "shapeless mass".Orb-weaving Spiders can also catch small snakes in their webs. Like the widow, they wrap their prey in silk and give venomous bites. The authors explained that the spider "extracts the tissue from its victim through the process of extraintestinal digestion." The spider then "extracts the dissolved tissue from its victim by the process of extra-intestinal digestion," the authors wrote. The spiders will only eat a small portion of the snake and leave the rest for scavengers such as ants, wasps, or flies.Nyffeler said that while the effects of black widow poison on snake nervous systems are well-studied, there is not much information about other spider groups. It is important to continue to research the venom components that specifically target vertebrate nervous system to determine how spiders can paralyze and kill larger snakes by venomous bites.Nyffeler, Gibbons and others also discovered that black widow spiders can outpower snakes up to 30 times their size. National Geographic published a 1933 example in which a garter snake weighing 8 grams was trapped in the web by 0.0225-gram cobweb spider. They wrote that the snake was 355 times more heavy than the spider. Similar to the pit vipers, tarantulas can also weigh up to 50 grams and have been recorded killing larger and more powerful ones.DOI: American Journal of Arachnology 2021. 10.1636/JoA–S-20-050 (About DoIs).
