It has all the makings of a fight night special: with speed and skill, a scrappy redback spider takes down an eastern brown snake over ten times its size.
In reality, this spider just got very, very lucky.
A video filmed in an engine shop in Victoria shows what appears to be a young eastern brown snake caught in the nearly-invisible web of a redback spider—“our pet redback,” the videographers joke in the Facebook caption. As the thrashing snake attempts to free itself, the spider dances closer, eventually managing to administer a bite that seems to temporarily immobilise the snake. (Watch an eastern brown snake swallow a carpet python.)
Although the video ends with the outcome of the battle still unclear, the tiny spider did in fact vanquish its outsized foe, confirms Brenton Maher, an employee of North Vic Engines who was present when the video was filmed. While spiders are efficient predators, however, the outcome of this rare occurrence came down to pure chance.
SPIDER KILLS SNAKE In an engine shop in Victoria, a female redback spider attacks a juvenile eastern brown snake that had become entangled in her web.
The spider in this video is a female redback (Latrodectus hasselti), easily identified by the vivid red marking on her bulbous abdomen. The genus Latrodectus, which also includes the five black widow spiders found in the United States, is known for spinning messy but especially strong webs: the resilient, elastic silk capture threads reach all the way to the ground and ensnare hapless insects, centipedes, or even other spiders.
These web threads are covered in droplets of glue, secreted by another of the spider’s up to seven specialised silk glands.
“If you pull your fingers through the silk, it’s almost like you’re tearing through fibers of paper,” says Paula Cushing, the curator of invertebrate zoology at the Denver Museum of Nature and Science.
Widow spiders’ webs are marvels of natural engineering, but vertebrates are usually able to break free.
In fact, some of the millions of Facebook viewers thought the sight strains credulity: believing the video was staged by embedding a fish hook in the struggling snake, many have condemned North Vic Engines.
“We don’t harm animals,” Maher says, adding that they certainly didn’t fake the scene to increase business. “We just filmed something we saw, and went about our day.” (Watch a giant spider drag a mouse.)
This juvenile eastern brown snake’s youth was the likely cause of its inability to escape. Once the redback managed to inject her venom, its odds of survival dropped dramatically.
Widow spiders’ venom contains a protein, called latrodectine, that immobilises their prey. In human beings, this neurotoxin interferes with the chemicals responsible for nerve signalling, causing “severe systemic pain throughout the body,” says Cushing. Beginning within half an hour of a bite, these symptoms—crippling stomach cramps, joint pain, swollen lymph nodes, facial contortions, sweating—can last for 48 hours without treatment.
This toxin likely acted much more quickly in the young snake, weakening it enough that the spider could further immobilise it in silk and commence digestion without risk of being crushed. Spiders’ mouths lack the structures necessary to chew particulate material, so all their food must be pre-digested. The redback would have injected the paralysed snake with digestive enzymes to break down its tissue, leaving a protein shake of sorts, which she could then ingest with her sucking stomach.
Spiders’ digestive systems are very efficient and their metabolism very low, meaning that they can survive for long periods of time with little food. Although she certainly couldn’t have consumed the entire snake, this spider would have feasted like a queen for two or three days, a meal which could sustain her for a month or more.
Eastern brown snakes are normally much more formidable foes. Their venom also contains neurotoxins, but one which can kill a human being in 15 minutes. (Learn more about the world's most toxic snakes.)
Much is made of Australia’s reputation as the “deadliest continent,” but as far as widow spiders go, that's not the case. “Redback spiders there are no more dangerous than black widow spiders here,” Cushing says, and while widow spiders wield a fearsome reputation in the U.S., it’s largely unfounded. Widow spiders are timid and rarely bite, and it’s even rarer for a bite to result in a fatality—in 2013, less than one percent of reported bites resulted in severe symptoms, and not a single one resulted in death.
Although it is true that the most dangerous spider in the world— the Sydney funnel web spider (Atrax robustus)—lives in Australia, spiders in general are nothing to fear. “They’re doing a lot of good out there in the world, controlling insect populations,” Cushing says.