Friday 27 April 2012

Hooded Tickspider

Image: Marshal Hedin
Armed with a remarkably thick exoskeleton and a host of other protective devises, Hooded Tickspider must surely be the most paranoid of all arachnids.

First of all, they're undercover. I mean, have you ever heard of them? Of course not! You'd have to be an extremely odd person to have heard of Hooded Tickspiders. You're not odd are you? You wouldn't admit to a thing like that, would you? Never mind.

They're also undercover in that they live in soil, leaf litter, bark and caves. Hidden, dark, easily overlooked places.

Another thing is that if you want to see one, you better be in the right part of the world. This isn't one of those "every continent except Antarctica" types. Hooded Tickspiders are only found in the humidity of western Central Africa and Central America. The rest of the world is all foreign. They do things differently over there and Hooded Tickspiders want nothing to do with it.

A Hooded Tickspider
(artist's impression)
They only reach up to 1 cm (0.4 in) in length, just to ensure that you forget all about them. It's like that guy next door who turned out to be a spy. "I never would have imagined.... he seemed so normal..."

It all worked so well that Hooded Tickspiders weren't discovered until the 1830s. It was a fossil. And it was thought to be a beetle.

This distrust has a cost. Or maybe it's the cause? There are only 60 or so known species of Hooded Tickspider, all in the order Ricinulei. Compare that to the order Scorpiones, with some 1,800 species. To say nothing of spiders. (More like 40,000!)

Of course, that's assuming none of the 400,000 described beetles are actually Hooded Tickspiders in disguise. With these elite agents, such an assumption may be unwise...

In any case, let's take a closer look at those defences. Just how paranoid are they?

Adam H Katona
A Hooded Tickspider, yesterday
(artist's impression)

We'll start with the hood. This thing is lowered over the mouthparts and has to be lifted up come dinner time. It's like one of those old helmets except it doesn't have eye holes. Hooded Tickspiders don't have eyes, just light sensitive areas on the sides of the head. Eyes are a sign of weakness.

Those aforementioned mouthparts are pincer shaped affairs, unlike spider fangs but akin to many other arachnids. They also have pedipalps which look like really tiny scorpion claws. They use them to manipulate prey such as termites and other small invertebrates. Both the pedipalps and the mouthparts are armed with all manner of sensory organs for tasting food before they commit to eating it. You can never be too careful...

Image: Marshal Hedin
Hooded Tickspiders scout ahead using their extra-long second pair of legs. So they slowly lumber along in their thick armour, seeking out prey. When they find something, they grab it with their pedipalps, open up the hood and bring it toward their mouthparts. They can even drop their hood down again to ensure a strong hold as their mouthparts set to work.

Then there's the chastity belt.
(I like learning things, but I'm not sure I should have Googled that).

Here's the thing: arachnids are divided into two parts, a cephalothorax and an abdomen. This is most notable in spiders, but it's the case for all of them even if the two parts are fused together into one big one.

Hooded Tickspiders are no different, except that their two parts are locked together. They aren't fused like a Harvestman, they're still distinct and separate with flexibility in between. But there's a complex mechanism that links them together. And beneath it, are the sexual organs.

It means that in order to mate, both males and females have to unlock themselves. The male then scoops up his spermatophore using his third leg (literally...) for the female to take away with her. Females carry the eggs in her hood, right in front of her face! Not keeping her eyes on them, she doesn't have any. So... keeping her sensory mouthparts on them, I suppose.

Clearly, she would never trust any babysitter. Her hatchlings even have 6 legs instead of the 8 they will later hvave when they grow and moult. They're BORN undercover agents!

I also have to inform you that the pictures here depict a Hooded Tickspider called Cryptocellus goodnighti. Isn't that a wonderful name? How sweet! How delightful! How... suspicious.


autopsyjude said...

that hooded tickspider is quite a beast. but that harvestman?!? omg what is that?!??! also haha i google chastity belt to i couldnt help it lolwut

TexWisGirl said...

chastity belts. ha ha!

Joseph JG said...

@autopsyjude: I know what you mean about that Harvestman! It seems to have slightly lizard-like eyes as well. Quite off putting. I've looked at them very briefly before:
but I'll have to give them a proper post.

Yeh, chastity belt was a far bigger and more modern subject than I was banking on.

@TexWisGirl: I really hope I can find another animal that has one!

Crunchy said...

Ironic that they're called "goodnighti," because I don't think I'm ever going to sleep soundly again.

Joseph JG said...

Hahah! I can scarcely imagine where they could have gotten that name from. Sounds like one of those sexy Bond villains!

Pearl said...

Got it. Gonna totally avoid the Hooded Tickspider.



Joseph JG said...

Ha! I think you'll find they're even better at avoiding you!

Anonymous said...

These undercover agents are really cool! Although human agents are usually not that well armoured. Do you have a picture of that hood of theirs somewhere? I cannot imagine how it would look like. I have looked at some pictures but I cannot tell what is actually the hood.

Joseph JG said...

I haven't seen any proper pictures of the hood, I'm afraid. I guess want we really want is to see them sitting there eating something. It seems like that kind of behaviour is really difficult to see in creature that's seldom spotted at all.

Hopefully one will turn up at some point. Ideally they'll leave a comment here, ha!

Till then, I guess that kind of photographic evidence is confidential...