Funnel-web venom devastates primates yet barely troubles many other animals
Australian funnel-web spiders rank among the most medically dangerous spiders on Earth, yet their venom seems fairly harmless to many animals. Primates, humans included, are the unlucky exception. Other creatures appear to carry antibody-like factors in their blood that bind and neutralise the toxins before they can do harm.
The family, Atracidae, lives only in Australia, mostly along the east coast, and contains 35 species in three genera. Bodies run from 1 to 5 centimetres, and like tarantulas they strike with fangs pointing straight down, powerful enough to pierce fingernails and soft shoes. They dig burrows in cool, damp, sheltered places, under rocks and rotting logs or in suburban rockeries, and string irregular silk trip-lines around the entrance rather than building a trapdoor lid.
The real risk is the wandering male. During warmer months adult males leave their burrows in search of females, and records link them to most, if not all, fatal bites. They are drawn to water, frequently tumble into swimming pools, and can survive several hours submerged and still bite when fished out. Contrary to popular belief they cannot jump, though they run fast. The Sydney funnel-web complex has caused 13 documented deaths, and in every case where the spider's sex could be determined it was male; female venom was once thought to be only about a sixth as potent.
The venom's toxins, called atracotoxins, force nerve cells to fire over and over, triggering floods of acetylcholine, noradrenaline and adrenaline. Before treatment existed, bites carried serious risk and severe cases averaged about 14 days in hospital. In 1981 a team led by Struan Sutherland at the Commonwealth Serum Laboratories in Melbourne produced an antivenom from rabbit antibodies, made using venom from male Sydney funnel-webs but effective against the whole family. Patients now typically go home within one to three days, and no deaths are known since it became available.
The venom may even help hearts. In 2021 University of Queensland researchers reported that a molecule named Hi1a, from funnel-webs on Fraser Island, could block the cell death signal that follows a heart attack, potentially limiting muscle damage.
Source: Australian funnel-web spider
