Goliath Birdeater: Behavior, Diet And Suitability As A Pet
What is a Goliath Birdeater?
The largest spider in the world is surrounded by misconceptions and confusions. Casually called the “Goliath Birdeater” and scientifically named Theraphosa blondi, this large hairy spider does not eat birds nor is it a tarantula. It is also only the largest spider by mass, the winner for length being the Giant Huntsman spider from Australia.
The Goliath Birdeater and other spiders commonly thought of as “tarantulas” are a part of the mygalomorph suborder which make up distant relatives of the original tarantula (Lycosa tarantula, a.k.a the Wolf Spider Tarantula, being the one and only “true” tarantula1). Mygalomorphs are thought of as primitive spiders because they have less spinnerets, one-piece abdomens, and their fangs point straight down, limiting their ability to bite.
Our Goliath spider also lacks keen sight that spiders such as jumping spiders have developed. “They rely instead on modified leg hairs, sensitive to vibration, to warn them of danger3.” They are complex and beautiful creatures but are notoriously hard to care for as pets as they are shy and require a lot of care.
What is the truth behind some common misconceptions?
While the T. blondi is fully capable of eating a bird, it rarely does as it prefers eating smaller insects, rodents, and even other arachnids. The name was developed when the “first European explorers in South America named the spider after seeing a specimen (an Avicularia avicularia Linnaeus, 1758) eating a small bird1.”
Many also assume that the T. blondi is dangerous, an idea that is certainly propagated by films such as Tarantula. To get theoretical, ethnozoologists created the “Entomoprojective Ambivalence Hypothesis”, the idea that people associate non-insects like spiders with insects and thus project feelings of fear, anger, and disgust onto those creatures.
Studies ran in South America showed that many persons believed that the T. blondi and other similar spiders have venom similar to that in snake bites. Some locals also believe that their venom is administered through the spider’s hairs rather than their fangs and that they will chase after people1.
The tarantula-owning community would certainly argue otherwise and they are certainly correct about the T. blondi not being dangerous. The venom from a T. blondi bite is enough to kill insects and small mammals but is nearly harmless to humans. The pain is comparable to that of a wasp sting: unpleasant but not horrendous. Bites are rare, however, because the T. blondi prefers to stay in its burrow and will also avoid biting unless it has been provoked4. The venom in the bites of South American mygalomorphs has never caused any serious medical concerns other than very minor swelling and discomfort5.
Do Goliath Birdeaters make good pets?
If your hope is to have a big, fuzzy, and cuddly pet, you’re probably better off getting a dog. However, if you are up to the challenge, the T. blondi makes for an interesting and challenging companion. “Due to their impressive size and reported aggression, they are very sought after in the pet trade today6,” Borris F. Striffler states in his overview of the spider’s behavior and life.
The first thing to consider when looking into having a T. blondi is safety. The Goliath does best when handled only when necessary and human owners will also do best. The bites are not dangerous but each spider has 10,000 to 20,000 hairs per mm2 on its abdomen. When the spider senses danger, it flicks the hind legs against those hairs which sends thousands of, what can best be explained as miniature porcupine spines, flying through the air7.
Each hair has a small set of barbs on the end. These hairs, when they come into contact with a person’s skin, mouth, eyes, nose, or ears can cause severe itching and irritation8. They can also cause small scratches on the surface of the human eye. Symptoms occur on a case-by-case basis with more sensitive persons reacting more severely than others9.
The fancy name for the T. blondi’s hairs is “urticating setae.” The spider has many uses for these hairs, the main one being defense, but others being eggsac construction and a sound production process called “stridualtion.” Other types of mygalomorphs use stridulation for sexual communication, but the Goliath only uses them for defense. It can create a loud hissing sound when it feels threatened10.
Different mygalomorphs have differing types of setae which are used for different purposes. T. bondi has type III setae which are 0.6 mm and are designed to cause irritation primarily for mammalian predators10.
A blog-journalist who encountered a T. blondi once on an expedition in the Amazon forest: “I could clearly hear its hard feet hitting the ground and dry leaves crumbling under its weight,” he wrote11, describing his first night-time encounter with the spider. People are rarely able to see the spider during the daytime as it is nocturnal and spends the daytime hiding in its burrow.
Since the Goliath is a rather exotic pet, it requires a bit of financial commitment. An initial purchase of a T. blondi ranges from $60 to $200, then the spider will require a large enclosure, natural and rich substrate, a humidifier, heat lamps, and live food. Overall, suplies for the spider will cost around $600-800.
While the T. blondi certainly isn’t an easy spider to care for, it is fascinating and a worthy challenge for an experienced tarantula caretaker.
How should I take care of a Goliath Birdeater?
The habitat is the most important and complicated part of T. blondi care. If you have a female, you intend to breed, it is important that the substrate be layered between 10–15 cm at least. If your spider is male, the burrowing space is important but could also be created artificially with a terracota pot. Since T. blondi spiders are both shy and nocturnal, having somewhere to retreat from everything is essential to their comfort.
Striffler recommends introducing small arthropods, European/tropical woodlice, and springtails into the substrate to help prevent ringworm infections. He also notes that adding bark pieces can help the spider conceal the burrow and that it is important to place the water bowl on the opposite end of the enclosure6.
Molting and Humidity
One of the most common reasons that a T. blondi won’t make it to adulthood is molting. The spider can get stuck inside the old exoskeleton and die or fatally injure itself while trying to remove the exoskeleton.
One way to prevent this from happening is to increase the humidity around the time that the spider is molting. “Humidity softens the moulted exoskeleton allowing it to be removed12.” Maintaining a high humidity in general is important to the Goliath’s health. A humidifier, ensuring the water bowl is constantly filled, and spray-misting the enclosure can all help. Monitoring the humidity is essential as Goliath’s need humidity levels constantly around 80%.
Diet
In terms of food, a T. blondi owner must be careful not to overestimate the abilities of their spider. In nature, the Goliath is an aggressive predator upon anything it can overpower. The record for largest invertebrate prey eaten by a spider was a giant earthworm that was around one meter in length13, and it was accomplished by this whopper of a spider.
However, in nature the T. blondi can be injured and killed by the same prey it stalks. To avoid the same thing happening to your spider, choose prey that is, at most, half the size of the spider. “Livefood insects such as crickets, locust, butter worms, meal worms, superworms, houseflies and cockroaches12” work best but larger prey should be introduced once or twice a month under direct supervision.
Like all other spiders, the T. blondi cannot eat solid food, rather it first poisons its prey with a swift bite, then drags it to its burrow where it injects chemicals that liquefy the spider’s innards. Afterwards it is able to suck the moisture and nutrients from the carcass. When T. blondi has finished its meal, remove anything leftover so that the spider is not harmed or stressed unduly12.
Goliath’s are readily available at some pet stores and at many locations online. The females are usually more expensive as they are useful for breeding and live far longer than the males, usually up to 20 years compared to the male’s 4-6 years.
Mating and breeding
T. blondi breeding is a difficult process but if you are interested in procuring baby Goliaths, here are a few tips. When introducing a male to a female, place the male into the female’s enclosure and never vice-versa. Female Goliaths do not always, but will occasionally eat the male rather than breeding with it. If the female is in a place where it is comfortable, it will be less likely to prey upon its sexual partner.
The two spiders will engage in a mating activity called “drumming” if they are interested. Usually the male will initiate by hitting the substrate with its front legs and pedipalps. Sometimes the female will reciprocate, indicating that it is interested. The breeding process can take hours but must be supervised. If the spiders begin to aggravate each other, cannibalism may occur. Attempting this breeding ritual multiple times makes it more likely that the male has inseminated the female.
It usually takes around 2 months for there to be any signs that the female has been successfully impregnated. If it was successful, the spider’s appetite will increase and its abdomen will begin to swell. It is important to feed the T. blondi as much as it will accept during this period so that it can build up the energy needed to create an egg sac. You will know the egg sac is soon to be made when the spider suddenly loses interest in food.
Once the egg sac has been formed, it’s important to let the female alone as much as possible. Goliath’s are very protective of their egg sacs and will carry them around, roll them, and massage them. They will also destroy and eat the egg sac if they become too stressed. Once you suspect that the spider nymphs have hatched, remove the egg sac from the mother for care and to avoid cannibalism.
Where do Goliath Birdeaters come from?
The T. blondi is native to the Guyana region of South America6. They tend to live in heavily forested areas where their unique burrows can be found. The most Goliaths are located in the Roura and the Kaw Mountains in French Guiana. Both of these locations are amoung the rainiest areas in the world, a testament to how well the Goliaths do in wet, tropical locations.
Their natural habitat, however, has a brief period of respite wherein three weeks pass without rain and the humidity drops to around 60% in the daytime but remains around 100% at night. Despite the changing weather and consistent rain, the web-lined burrows in which the T. blondi reside maintain stable temperatures throughout the year6.
When locals see the mygalomorphs wandering, it is usually raining. They’re commonly noticed after thunderstorms crawling along roofs or roads. When it is not raining though, locals have found the Goliaths in abandoned and dark areas such as tree holes, logs, storage rooms, and other piles of things11.
These areas are comfortable for the shy, nocturnal arthropod. Goliaths are most comfortable outside their lairs when it is dark and damp outside, for example when it is nighttime or when it is raining. During daylight, the T. blondi can occasionally come out of its burrow but rarely moves more than a couple feet away12.
Sometimes more interesting than the spiders themselves are how those who live in proximity to their natural residences interact with them. In South America, locals often refer to mygalomorphs as “caranguejeiras” or, in English, “bird-spiders.” This is partially due to the myth that they commonly eat birds but can also be attributed to tree spiders who use their hairs and multiple legs to help them perform graceful leaps to the forest floor, much like little birds.
A jungle tribe native to the spider’s habitat occasionally eats T. blondi roasted. The cooking process involves first singing off the spider’s hair to avoid an uncomfortable eating experience, then a good roast in banana leaves13. According to tarantula expert, Rick West, “a cooked tarantula tastes similar to a prawn.14” The spider isn’t hunted regularly, but those who have tried it consider it a local delicacy.
What should I remember?
An important thing to consider when looking into having a Goliath Birdeater of your own is how the spider came to your country. Hunters going into the wild and capturing spiders are often cruel, underfeed the spiders, and diminish the wild population causing some species of tarantulas to become endangered. The most ethical way to get a Goliath is to get a man-bred one. They are usually far-better cared for and their captivity doesn’t effect the lives of the T. blondi in the wild.
Goliaths are certainly fascinating creatures for the arachnophiles among us and an absolute nightmare for arachnophobes. Either way, caring for them is not for the weak-hearted. They are, effectively, an exotic and wild animal not intended for captivity. However, take care of them well and they can be your cute eight-legged companion for many years.
Sources
- Neto, Eraldo M Costa. “Bird-spiders (Arachnida, Mygalomorphae) as perceived by the inhabitants of the village of Pedra Branca, Bahia State, Brazil.” Journal of ethnobiology and ethnomedicine vol. 2 no. 50. 13 Nov. 2006.
- https://en.wikipedia.org/wiki/Mygalomorphae
- https://www.nationalgeographic.com/animals/invertebrates/g/goliath-birdeater/
- Smith, Robert Lloyd. “Venomous animals of Arizona.” Bulletin A-University of Arizona. Cooperative Extension Service (USA)(1982).
- Bertani R. et al. “Mygalomorph spider bites: a report on 91 cases on the state of São Paulo, Brazil”. Toxicon vol. 32 no. 10. October 1994.
- Striffler, Borris F. “Life history of Goliath Birdeaters – Theraphosa apophysis and Theraphosa blondi (Araneae, Theraphosidae, Theraphosinae)”. British Tarantula Society vol. 21. January 2006.
- Soerensen, B. “Animais Peçonhentos-Um Estudo Abrangente: Reconhecimento, Distribuição Geográfica, Produção de Soros, Clínica e Tratamento dos Envenenamentos.” Atheneu. 138p (1996).
- Cardoso, João Luiz Costa, et al. “Animais peçonhentos no Brasil: biologia, clínica e terapêutica dos acidentes.” Revista do Instituto de Medicina Tropical de São Paulo 45.6 (2003): 338-338.
- Lozoya, X., and S. Ibáñez-Bernal. “A cien años de la zoología médica de Jesús Sánchez.” México: Instituto de Seguridad y Servicios Sociales de los Trabajadores del Estado (1993).
- Bertani, Rogério; Guadanucci, José Paulo Leite. Zoologia; Curitiba Vol. 30, Iss. 4. Aug 2013.
- https://thesmallermajority.com/2014/10/08/the-sound-of-little-hooves-in-the-night/
- https://web.archive.org/web/20131031034832/http:/www.care-sheet.com/index/Theraphosa_blondi
- Mammola, Stefano et al. “Record breaking acheivements by spiders and the scientists who study them.” PeerJ no. 5. October 31, 2017.
- http://www.birdspiders.com/world.php
