(Previous Spider Fridays available
here! Just use the tag "Spider Friday" or "spiders".)
Welcome, Kossacks, to another scintillating episode of Spider Friday--your weekly insight into the world of our eight-legged friends.
Our topic of discussion today: size matters! And no, I'm not talking about the depth of the embolus grooves on a male's pedipalps. I'm talking about a 12-inch-long...legspan. I'm talking about the biggest spider in the world.
Enjoy...Spider Friday!
LARGEST SPIDER IN THE WORLD: THE GOLIATH BIRD-EATER, T. blondi.
Kingdom: Animalia (Animals)
Phylum: Arthropoda (Arthropods)
Class: Arachnida (Arachnids)
Order: Araneae (Spiders)
Infraorder: Mygalomorphae (primitive spiders)
Family: Theraphosidae (Tarantulas)
Genus: Theraphosa
It should come as no surprise that the world's largest spider is a tarantula. The question is--do you know what a tarantula even is? Let's start by defining just exactly what a tarantula is.
Tarantulas are generally large and hairy, yes. True tarantulas all belong to the Theraphosidae family, though there are some "dwarf tarantulas" and "atypical tarantulas" that I can cover later on. But the morphological feature that distinguishes true tarantulas from other mygalomorph spiders such as the Sydney funnel-web I've gone over earlier, or related spiders like the trapdoor spiders, has to do with their feet!
You see, tarantula feet--called tarsi--each have two claws, each comprised of thousands of tiny hooks, as well as tufts of very small, fine hairs. This foot arrangement is unique to tarantulas. Because of a principle of physical chemistry called the van der Waals force--which I don't fully understand--these claws and tufts of hair give tarantula feet such adhesive strength that they are able to climb smooth polished glass.
Tarantulas come in various sizes. Some are only a couple of inches when fully grown. But they can also come in a wide variety of colors--these spiders are a lot more than your typical big, brown spider. Just check out this cobalt blue--H. lividum--from Thailand:
Or the Indian Ornamental, P. regalis:
There's a little bit of a difference between old-world and new-world tarantulas. Tarantulas from Africa and Asia tend to be far more aggressive than American tarantulas. Tarantulas usually aren't very venomous to humans, though some can produce a painful bite concomitant to a wasp sting. New world tarantulas have a defense mechanism other than biting--they have irritating hairs (called "urticating hairs") on their abdomen they they shed with their back legs. These hairs can cause a rash, and if they get into your eyes, it can be really painful. Believe me, I know. My tarantula has let me have it before.
Tarantulas are long-lived compared to other spiders--they generally have a life-span of several years. There have been reports of tarantulas living up to 20 years in captivity.
So there's a brief overview of tarantulas in general.
But just how big is this sucker? How about an average of 120 grams and a 1-foot legspan from the tip of the right front to the tip of the left back? How's that for intimidating?
As you can see, it's a pretty big spider. And if you've ever seen one in person, you don't easily forget it. What's unusual about T. blondi is that it can actually make a hissing noise when disturbed by rubbing its legs together. It's the only spider that will audibly let you know when it's irritated. And irritating it probably isn't a good idea.
These spiders aren't very striking in appearance, outside of their size. They're large and brown, covered with hair, and have an abdomen that seems slightly larger in comparison to their size that most tarantulas seem to have. They live in the northern part of South America--in Venezuela and further east into Guyana and Northeastern Brazil. Lots of people--myself included--like to keep tarantulas as pets, but only experienced spider enthusiasts can successfully keep T. blondi as a pet--they're very sensitive and require a very precise environment to ensure their health.
T. blondi will eat anything it can get its hands on, but that usually includes insects and amphibians more than birds or mammals:
BITES:
The venom isn't very dangerous to humans, like most tarantulas. But, come on. Do you realize how big that thing is? The fangs can be half an inch long:
If you ever get bitten by one--and the only way that could really ever happen is if someone you know keeps one as a pet and you try messing with it--the most important thing to do is prevent infection of the puncture wound, because you might as well have stabbed yourself with a pen-knife.
LIFECYCLE:
T. blondi females mature in around 3 years, with a lifespan of 7-15 years. Like most other spider species, males mature at around the same time, find a mate and die shortly thereafter.
Mating is a dangerous and complicated affair, especially for the males. Let's talk about tarantula mating for a bit, because T. blondi follows the same process--just, on a larger scale.
Upon making his final molt into maturity--the molt at which he gets his developed pedipalps and his mating hooks on his forelegs--a male tarantula will make a sperm web using special spinnerets that are located on the epigastric furrow--the sex organ region of the spider.
The male will then deposit sperm from his epigastric furrow onto the web, and then collect inot the grooves on his embolus--the bulbous appendage at the end of his pedipalps:
At that point, the sperm is stored and the male is ready to start hunting for mates. So, from this point on, we'll be dealing with T. blondi:
The male will approach the female with trepidation, and start drumming his palps on the ground outside her burrow to announce his presence. For captive breeding, you can let the two spiders get introduced on separate sides of the glass for the safety of the male:
Once the female has accepted the male's presence, the process works similarly to what I described in the sydney funnel-web: the male will lift up the female and use his foreleg hooks on her fangs while depositing his sperm into her epigastric furrow.
After mating, the female will produce an egg sac in a few months. The nymphs will molt once in the egg sac, and then emerge several weeks later:
And from they, they disperse--and then they grow:
And grow:
AND GROW!
That's pretty much it for the T. blondi. It's certainly the heaviest spider on average--but the biggest spider on record in terms of total legspan isn't a T. blondi--it's a close relative, the T. apophysis, the Pink-Toed Goliath:
This species holds the all-time record, with one specimen measuring a 13-inch legspan.
Well, that should just about do it for Spider Friday. Make sure to check back next week, because I haven't decided what I'm doing yet.