Tarantulas, the large, hairy spiders belonging to the family Theraphosidae, often inspire fascination due to their sheer size. Their dimensions set them apart from most other arachnids, leading many people to wonder which species holds the title as the largest in the world. The search for this record holder focuses on specimens with the most impressive overall bulk.
Identifying the Record Holder
The largest tarantula species is the Goliath Birdeater, scientifically named Theraphosa blondi. This enormous arachnid is the champion among all spiders globally, characterized by its substantial mass and overall body size.
Goliath Birdeaters can attain a weight of up to 175 grams (6.2 ounces), a mass comparable to that of a small terrestrial mammal. These spiders also boast a leg span that can reach up to 30 centimeters (nearly 12 inches), roughly the size of a dinner plate.
The Birdeater has a body length that can measure up to 13 centimeters. Their coloration ranges from dark to light tan and brown, often with a golden hue. Their entire body is covered in thick, protective hair.
Defining “Biggest”
The designation of “biggest spider” requires clarification regarding the metrics used for measurement. The Goliath Birdeater earns its title based on mass and body size, as biologists generally consider the specimen with the greatest overall bulk or weight.
In contrast, other spiders may possess a greater length when measured from leg tip to leg tip. For instance, the Giant Huntsman Spider (Heteropoda maxima) holds a similar record for the largest leg span, sometimes matching the 30-centimeter measurement of the Birdeater.
However, the Giant Huntsman Spider has a much flatter and less massive body compared to Theraphosa blondi. The Huntsman’s comparatively smaller mass means it does not rival the Goliath Birdeater in terms of overall bulk. Therefore, when the question concerns the “biggest tarantula,” the Goliath Birdeater’s superior mass makes it the accepted record holder.
Life and Location of the Largest
The Goliath Birdeater is native to the upland rainforest regions of northern South America. Its range includes countries like Suriname, Guyana, French Guiana, northern Brazil, and southern Venezuela. These spiders are terrestrial and primarily inhabit areas with high humidity, such as marshy or swampy forest floors.
They are nocturnal predators, spending their days hidden inside deep, silk-lined burrows that they either excavate themselves or take over from other animals. The burrows provide a secure, humid environment and a base from which to ambush prey. Their poor eyesight means they rely on the sensitive hairs covering their bodies to detect vibrations in the ground.
Despite the misleading part of its common name, the Birdeater rarely preys on birds. Its diet consists mainly of earthworms, large insects, frogs, and toads. However, due to its size and opportunistic hunting behavior, it is capable of killing and consuming small terrestrial vertebrates, including rodents, lizards, and sometimes snakes.
When threatened, the Birdeater employs several defensive tactics. It can rub specialized bristles on its legs to produce a loud hissing sound, known as stridulation, as a warning. The spider also defends itself by kicking off a cloud of urticating hairs from its abdomen, which can cause severe irritation to a predator’s skin and mucous membranes.
While they possess fangs that can reach 2 to 4 centimeters in length, capable of piercing human skin, the venom itself is generally considered mild. The effects of a bite are comparable to a wasp sting. The spider’s primary defense against humans is the release of its irritating hairs.