General description

Therophosa blondi is currently recognised as the largest spider in the world, with females reaching a leg span of ten inches & males reaching more than eleven inches. The current record holder is a male that had a leg span of over twelve inches. This species is a very robust & thickset spider that can be dark brown to light tan in colour.

Everything about this spider is big. The abdomen can reach the size of a small orange & the fangs can be more than an inch long. Females have been known to weigh as much as 6ozs, which is about the same as a small jar of coffee. This spider is one of the New World species, so its primary defence is to kick urticating hairs at any would-be attackers. These are very irritating, causing a similar reaction to nettle rash (except it can last up to 48hrs). The affected area needs to be rinsed under cold water to remove any loose hairs.

T. blondi also has the ability to stridulate, with the subsequent noise being akin to a snake hissing. If this fails to deter predators, or even humans, it will bite and, taking into account the size of the fangs, the mechanical injury is extremely painful. The venom causes reddening of the bite area, nausea, vomiting, fever & temporary paralysis. The effects can last up to a week, with possible recurrence of cramps at the bite area. These can even re-occur for up to a year after the original bite. This spider’s distribution is quite widespread, being found in Guyana, Surinam, Venezuela & north-eastern Brazil. This large range may account for the great colour variation within the species.

This species is normally found in burrows which are six-inches across & up to two-feet in depth. These burrows are often located along the moist areas bordering riverbanks & trees. These spiders are most active during the rainy season, as humidity levels are higher. When it is dry they retreat into their burrows, as the moisture in the soil maintains a comfortable humidity level for the spider.

Enclosure & substrate

As this is such a large spider it needs a large enclosure. A terrarium measuring 18” X 12” is sufficient and a small aquarium with a vivarium lid is ideal for the purpose. You could also use a larger tank divided in two if keeping more than one adult or for breeding purposes. Vermiculite is possibly the best substrate to use, as it is cheap & readily available from garden centres & reptile stockists. Vermiculite needs to be moistened before use & there are several ways to do this:v i. Cut the top off the bag, pierce the sides with a small screwdriver & fill with water. Allow sufficient time for the excess water to drain out.
ii. Pour the required amount of substrate into a bucket & add water whilst mixing with a spoon. This way the vermiculite does not become too moist.
iii. Put the dry vermiculite into the enclosure & spray with tepid water.

Another substrate that can be used is peat moss, which this can be purchased from garden centres in large quantities. Peat moss has one downfall, however, as it can encourage mites & fungus. It also becomes compact & hard, not allowing the water to seep through, so it requires to be sprayed more often than vermiculite. Cage furnishings are simple and the first item that the spider will need is a burrow. If the enclosure is large enough, a bucket cut in half & buried in the substrate is the best solution that I have found. Other burrows can be made from plant pots & cork bark. The only other furnishing required is a water bowl & I have found that the ceramic bowls for hamster cages are ideal as they are cheap, easy to clean & do not look to out of place.

Real plants are not a good idea for the following reasons:

i. They will be trampled when the spider decides to go walkabout.
ii. Plants require full spectrum lighting & as the spider is nocturnal it will reduce the chances that you will see it.

Spiderlings & juveniles are easier to house when they are young. The plastic tanks, such as the “Hagen Home”, sold by most pet shops are perfect for growing spiders as they are available in a variety of sizes & are relatively inexpensive.

Growth rate

Males take 1.5 years to mature, whilst females can take around 3 years to mature. The males of this species lack tibial spurs on their front legs.

Longevity

The female Goliath can live up to twelve years, with the males living for three years.

Food

T. blondi spiderlings will eat half-grown brown crickets, on which they should be fed every other day. It is important that only 1-2 food items are placed into the enclosure at a time as crickets are omnivorous & uneaten food items may prey upon the spider. Juveniles can be fed adult brown crickets, medium black crickets, small hoppers & mealworms. It might also be worth trying them on pinkie mice to find out if they will adapt to eating pre-killed prey as this will be beneficial for when they become adults. Adult spiders will eat almost anything that is placed in the enclosure, including adult crickets (black & brown), jumbo mealworms, adult locusts & small to medium defrosted mice.

One very important factor to bear in mind is that it is very easy to over-feed these spiders and it does not take to long before the abdomen becomes distended. This can be dangerous to the spider, as it makes the abdomen vulnerable to rupturing. With adults it is best, therefore, to give them a feed about once a month.

In the wild the diet of T. blondis also includes small birds, snakes & lizards. When feeding mice to captive animals (including spiders) it is important to remember that it is illegal to feed a living vertebrate to a predatory animal (this includes all vertebrate prey items, such as mice, rats & lizards). Fortunately I have found that many of the spiders I have kept will readily accept defrosted food items that have been allowed to thaw out for around twelve hours.

It is not normally necessary to tease the spider with the food item, but if you do decide to do this it is advisable to use a long pair of feeding tongs. I generally lay the food item just outside the burrow entrance. It seems that tarantulas may have the ability to “smell” certain types of prey items, as it does not take long for them to realise that dinner is sitting at the door. The only problem with mice is it that, as it can take a spider as long as twelve hours to eat it, after a while it will start to smell a bit. The spider will constantly drop the food & re-wrap it in silk and at this point I gently move the mouse from under the spiders nose. After a while the spider will retreat back into its burrow & start to preen itself. I then remove the webbed area to remove any remains of the meal to prevent any chance of a mite infection occurring.

Mice are a good food item to acclimatise a newly acquired specimen or to condition a female for breeding. I never use rodents as a staple diet, but more as a treat. Remember tarantulas only go off their insect diet when a moult is due or when they have simply had enough.

Moulting behaviour

Like all spiders, tarantulas need to shed their exoskeletons in order to grow. This is called moulting and prior to a moult the spider will stop feeding for about 2-4 weeks, depending on species & size. As a rule spiderlings will moult much more frequently & only go off feeding for a couple of days. If the spider has a bald abdomen and has started to go bluish black this is a good indicator of an impending moult as it is the fluids that separate the two skins that cause this discolouration. Most tarantulas will moult on their backs, and the Goliath is no exception. When a moult is imminent the spider will retreat back into its burrow & lay down a thick web. It will also mix in urticating hairs to give it some protection, as they are extremely vulnerable when moulting. It is imperative that there are no food items in the enclosure prior to a moult as these could harm the spider at this vulnerable time.

With the moult impending, the spider increases the pressure and some of the separating fluid can be seen around the front of the carapace. The fangs & chelicerae are the first to be withdrawn, followed by the legs & abdomen. One thing that you must never do when you find your spider on its back is try to turn it over as this can kill the animal. Remember, it is not dead - when spiders die they are generally found the correct way up, with their legs tightly withdrawn underneath their bodies.

After moulting the spider will remain on its back for some time & you may notice it moving its legs. You will also notice how much bigger it has grown. After a few hours the spider will right itself & begin absorbing some of the nutrients from the old skin. It is best left alone whilst it does this and it will be some time before it begins feeding again.

Moulting times and frequency vary, depending on the size of the spider. Spiderlings will moult once a month, with the actual moult lasting around 2hrs. Adult spiders will moult once a year, with the moult lasting some 24hrs. It will take several days for both the skin and the fangs to harden but about 2 weeks you can try feeding the spider. If it refuses to eat, take the food item out & try again in a couple of days.

Cleaning

Tarantulas are one of the cleanest animals that can be kept as pets. All they pass is a liquid that has no odour, which can occasionally be seen on the side of the enclosure. If the enclosure is spot-cleaned once a week to remove any uneaten remains or dead prey items then this is usually sufficient. The water bowl must also be cleaned regularly, as it is not uncommon for the spider to place substrate into it. If this schedule is kept then the enclosure will only need a full overhaul every six months. When it is time to do this the spider will need to be removed from the enclosure & placed into secure temporary accommodation (this is when the Hagen homes become handy). All of the old substrate should be discarded and the enclosure washed out with a mild detergent & rinsed thoroughly before drying. Replace the substrate and, if necessary, the cage furnishings. Finally, make sure the temperature & humidity are correct before re-introducing the spider.

Temperature & humidity

T. blondi comes from the tropical rainforest, so it is important to replicate these conditions in captivity; this is actually easier than it may first seem. The temperature should be 75-88 degrees Fahrenheit and this can be achieved by using heat mats/strips that can be purchased from pet shops but if you have a large collection then you may use the heat cables that are available at garden centres. The best solution for the majority of people remains the heat mat as they are available in a range of sizes & are not very expensive. It is important to use these in conjunction with a thermostat. A variety of different thermostats are now available, but all that is required for a heat mats is a simple Mat Stat. These cost around £20, so they are relatively inexpensive to purchase. The heat mat should be placed either at one end of the enclosure or at the back to provide a temperature gradient for the spider. This is so that if the spider gets too hot it can move somewhere cooler & vice versa.

The second condition that needs to be replicated is the humidity, which should be around 80-90% for the Goliath. Humidity is very easy to control by keeping the substrate moist & lightly spraying the enclosure every couple of days. It also helps if you keep the water bowl near the heat source so that it can slowly evaporate and keep the humidity levels high. Purchasing a humidity and temperature gauge will enable you to monitor conditions in the enclosure very easily.

Captive behaviour

This section is from my own personal observations and there will naturally be some difference in the behaviour of different specimens. Over the seventeen years that I have been keeping tarantulas & scorpions, I have had four Goliaths in my collection. All of these, including the 10” adult female that died after 11 years in my care, I have reared from spiderlings. I have noted that when they are spiderlings they have more of an urge to come out of their burrow & wander their enclosure in search of food. This has certainly been the case with three of the spiders, whilst the other one prefers to stay in her burrow & wait for the food to come to her.

The adult female that I currently own is around 7”” legspan & when I first obtained her she showed no interest in her burrow. I was then using half a clay plant pot that was about 6” in diameter, so after about eight weeks I decided to try something different. I cut a bucket in half, made sure that there was no sharp edge and placed the bucket in the enclosure completely buried in the substrate, just leaving a small hole, which was barely large enough for her to get in. Within a couple of hours she had enlarged the hole & settled down quite happily and it is now quite rare to see her out of her burrow. The previous adult female that I owned was just the opposite, as she used to sit ¾ of the way out of her burrow, and it was not unusual to see her having a wander around the enclosure.

It is a good idea not to have anything for these spiders to climb, as their size & weight means they can easily fall & injure themselves. It is not unusual to see them trying to climb the enclosure sides. One thing that I have noticed with spiderlings & juveniles is that when they moult they actually grow considerably more each time than most other spiders that I have kept - within their first year they can achieve a 5” leg span. In the wild this would be a bonus in that they are less likely to be picked off by predators & they also have a more diverse range of food items available to them.

I have observed that this is a species which seems to prefer an open water dish. For my spiderlings, I always place a piece of cotton wool in the dish to prevent any risk of drowning. As they reach juvenile & sub adult ages I remove this & they have an open water dish that is around half full.

Therophosa blondi is certainly an impressive spider, indeed it is considered the largest spider in the world, and makes an excellent captive. Its ease of maintenance and willingness to feed make it of particular interest and I would strongly recommend the species.