Arachnophobes look at this instead, it’s time to talk all things giant spider. We bring together the ecology and life history of two of the world’s most enormous arachnids. 

First up we have what many consider the largest spider in the world, the Goliath birdeater (Theraphosa blondi). This member of the tarantula family is the biggest arachnid by body length and mass but is outdone on leg span by the second massive spider. 

Meet the Goliath Birdeater Tarantula

The Goliath birdeater lives in northern South America where despite what its name suggests, it does not spend all its time eating only birds. Instead, these nocturnal giants emerge from their burrows at night and prey upon invertebrates, eggs, or even small rodents and the occasional small bird.

According to the Smithsonian Zoo, the Goliath birdeater tarantula can grow to around 12 centimeters (4.75 inches) in diameter of the body and a leg span of 28 centimeters (11 inches). These arachnids have varying lifespans depending on sex: the females can live up to 20 years in the wild rainforests of north Brazil, Venezuela, and beyond, and the males often die after mating and have a lifespan of between 3-6 years.

These hairy brown and black tarantulas possess fangs and venom. Though it would be unpleasant to receive a bite from one, the venom is not fatal to humans. Goliath birdeaters can also produce noise by rubbing together bristles on their front legs in a process called stridulation. It is said the noise produced by these tarantulas can be heard over 4.5 meters (15 feet) away. 

In some parts of South America, the birdeater is considered a delicacy; the hairs are carefully singed away and the spider is roasted in banana leaves before being eaten, according to National Geographic. A study examining nutritional potential found that a Goliath birdeater could provide around 109 calories (kcal) per 100 grams. 

Meet the giant huntsman, the world's largest spider by leg span 

The only spider to best the Goliath in terms of size is the giant huntsman spider (Heteropoda maxima), which has a whopping leg span of 30 centimeters (11.8 inches). Like the Goliath, these spiders don’t build webs but rather hunt down prey. This spider was first discovered in a cave in Laos in 2001 making it rather more elusive than its South American counterpart. These huntsmen are often mistaken for tarantulas though they are spiders in the family Sparassidae. 

Giant huntsmen are also extraordinarily fast, able to move nearly a meter per second when chasing their prey. They have a much flatter body plan than the Goliath, making them able to hide in tree bark and crevices much more easily. 

Similarly to the Goliath, the huntsman has venom that is luckily not deadly to humans, and instead feasts on insects, small lizards, and frogs. 

These two bemouths of the arachnid world are incredibly impressive, not just for their size but for their adaptations to the complex environments in which they live.