The Goliath Birdeater is well-named, as it represents both the largest and heaviest spider in the world.
The Guinness Book of World Records reports that the largest known specimens can reach 28cm (11″) across the legs, and weigh in at up to 170 grams.
That said, even with these dimensions it is difficult to appreciate just how large and intimidating these spiders really get until you’re faced with a big adult female with an abdomen the size of a golf ball!
The Goliath Birdeater was first described by Pierre Andre Latrelle in 1804. Since it’s scientific discovery the species has gone through an astonishing range of different Latin names.
At present it is known as Theraphosa blondi, though at various times in the past has also been known as Theraphosa leblondi and Theraphosa blondii.
Occasionally these names are still used on the Internet, but rest assured that all relate to this one particular species.
That said, there are two other closely-related species, known as Pseudotheraphosa apophysis and Theraphosa stirmi, which differ only slightly in adult size and appearance.
For the purposes of this guide we will focus our attention only on T.blondi which is found in the rainforests of Northern Brazil, Southern Venezuela, Guyana and French Guiana.
The Guinness World Record holder was found in Rio Cavro on 1965, while scientists believe that some of the highest population densities of this species are to be found in the Roura and Kaw Mountains of Guiana, which are reputedly some of the rainiest places in the world.
Interestingly, this species is considered quite a delicacy by some local tribes, with the Piaroa and Yanomamo Indians having been reported catching these spiders before roasting them on a fire and eating them.
It is also one a limited number of species that can audibly “hiss” – a process known as “stridulation” – by rubbing together specialised hairs on its legs. A full grown Golith Birdeater rearing up and hissing is not a sight for the faint-hearted!
Goliath Birdeater Caging
It should come as little surprise that the world’s biggest spider also requires a good-sized cage in captivity.
A range of plastic or glass containers may be used, but it it recommended that these solitary spiders should be kept in tanks measuring at least 45cm long by 30cm deep.
As impressive specimens, which often sit out in the open, this is a perfect spider to turn into a jaw-dropping display animal.
In the past, tarantula keepers have used large glass aquariums to keep Goliath tarantulas, but it is important to remember that these are strong spiders which can climb well despite their bulk.
A close-fitting lid is therefore critical, if you don’t want to have an awkward discussion with the next-door neighbour.
My personal preference for these spiders is one of the larger Exo Terra vivariums. These are glass tanks with excellent ventilation and a locking grill lid. The doors at the front can also be locked shut, creating a fully secure but very good-looking home for these spiders. Given enough space, it can be fun to furnish the cage in line with their rainforest habitat, including artificial plants and so on in their habitat.
Goliath Birdeaters are powerful burrowers in the wild, so they will need not only a suitable substrate to dig in, but also at least one good-sized hide. Personally I like to use a number of pieces of curved cork bark, under which my spiders often conceal themselves during daylight hours.
Heating & Temperature
Goliath Birdeaters like a warm, tropical environment in captivity, which means that the tank should be heated artificially to around 25-28’C. As with all tarantulas, however, this heat not not be provided uniformly across the cage, but instead a range of temperatures should be available.
In this way your spider will be able to seek out the temperature that suits them best within the tank.
Providing a temperature gradient like this needn’t be difficult. All you need to do is heat one area of the tank directly, but leave the other unheated.
A heat mat is generally the easiest way to accomplish this, either stuck to the side of the tank (ideally) or alternatively placed under the cage. Aim to place the cage no more than half on the heater, to retain a cooler area if your spider desires it.
As most heat mats aren’t thermostatically controlled by default, but just give out a gentle background heat, it is strongly advised to buy a thermometer (and ideally hygrometer too) in order to monitor the temperatures in your tank. In this way you can be confident that your spider is being kept at the required temperature.
Water & Humidity
Theraphosa blondi comes from humid, moist rainforests, so a high level of humidity is recommended for this species. This should be provided by regular misting of the cage using a houseplant spray gun.
Note that a stale, stagnant environment should be avoided; in tarantulas it is important to maintain both a high humidity and healthy levels of ventilation to boot.
This is another reason why the better-quality tarantula tanks suitable for Goliaths typically have some kind of grill or mesh included as part of the design to assist with keeping the air fresh.
A shallow water dish should be provided at all times, and the bowl should be thoroughly cleaned, and the water changed, on a regular basis to keep it hygienic. It is not unusual to find this species drinking from their bowl.
While Goliath’s are typically known as “bird eaters” it is believed that this name is derived from an early painting, showing a large South American theraphosid feeding on a hummingbird.
While there are occasional reports in the scientific literature of Theraphosa blondi feeding on birds (including one unfortunate case where biologists set up nets to sample local birds, only to find a Goliath chomping his way through one of the captured specimens) this species tend to feed much more commonly on invertebrates.
It is believed that earthworms make up a large proportion of their diet in the wild.
In captivity a range of larger insects may be fed to adult specimens. Suitable feeder insects include adult locusts and large cockroaches. While they will willingly eat smaller prey items such as crickets or mealworms, the number needed to satiate the hunger of such a large spider can make them an expensive and impractical solution.
Like many tarantulas from equatorial areas, Goliaths are quite a fast-growing species. The spiderlings are also among some of the largest in the world, and they can pack on an astonishing amount of weight in their first year. As a result, expect to feed your Goliath regularly if they are to grow rapidly.
Some keepers have fed mice to their Goliaths before. While an adult Goliath can (and will) dispatch a live adult mouse, this is not to be recommended. Besides being a rather gruesome end for the mouse, it is not unheard of for rodents to fight back, causing injuries for the spider.
Additionally, while a snake will eat a mouse whole, tarantulas will mash it up before consuming it. This can create quite a mess (and smell) that requires some serious cleaning the next day. If you opt to feed rodents to your Golith, be sure to buy dead, frozen rodents as sold for snake owners, and be prepared for some extra cage cleaning duties.
While there will always be some keepers who try to handle almost any species – and love to make YouTube videos about how brave they are – the Goliath Birdeater is a species probably best not held.
There are a number of reasons for this. Firstly, their size can make handling quite difficult, as an adult female will be larger than both your hands put together. You should also remember that their fangs remain in proportion to the body, and may be an inch long in large specimens! I personally wouldn’t want those biting down on my hand!
Then there’s the general attitude of Goliath Birdeaters. They tend to be quite a skittish, even mildly aggressive species in my experience.
While they may not try to bite regularly, they are very prone to kicking off the urticating hairs on their abdomen.
These are highly irritating, and can lead to itchy skin with rash-like pinpricks present. Inhaled they make the nose itchy and uncomfortable, and urticating hairs in the eyes can be very serious.
Lastly, one needs to consider the spider itself. Goliaths are large tarantulas, and if dropped from a height can do themselves serious injury. The abdomen in particular is huge, yet soft and fleshy, so can rupture easily if dropped. Once this has happened there is rarely anything the tarantula owner can do to help.
All things considered, while some keepers will obviously disagree, I would suggest you avoid handling your Goliath unless absolutely necessary, and instead rely on long forceps and plastic tubs to move your spider around as necessary.