Amplypygids – Tailless Whip Scorpions

20mm | January 19, 2011 | Armonia Nature Preserve, Limon Province, Costa Rica

These fearsome looking arachnids have an order to themselves, Amblypygi. Though commonly called tailless whip scorpions or whip spiders, they are neither. Intimidating though they may look, they aren’t dangerous and possess no venom. They are quite timid in fact, and I had to take care not to scare them away while photographing them.

Here’s how you might expect to see one actively moving about, with its oversized first pair of legs outstretched.

Longest legs extend outside frame

That first pair of legs is modified for use as antennae. They wave them about, sensing and probing. While the body of this one measured only 2cm, each one of those antenniform legs was 8cm long!

Eight Eyes

The have flattened bodies, useful for hiding in crevices and other tight places during the day. They hunt at night, and I usually see them on the trunks of trees. These first images, however, were of one I spotted on the side of a creek bank. This next one was on a downed tree that had fallen across the same creek.

Raptorial Palps Extended

Its palps were initially extended as shown here, perhaps in preparation for an ambush. After I spooked it, it drew them in closer to its body.

What I found most interesting though, were a few females I spotted carrying egg sacs.

Female with egg sac

Actually, the egg sac is glued in place. She’ll carry her eggs around like this for at least 3 months, during which time she generally won’t eat. If she did, the eggs might become unglued.

Egg sac closeup of another female

Based on this genus key, all these individuals appear to be in the genus Paraphrynus. In fact, they must be Paraphrynus laevifrons. I realize the linked pages are for La Selva specifically, but La Selva and this location are both in the Caribbean lowlands. Further, iabin shows only this single species for that genus, and even has a collection record not far from my site.

Amblypygids really are fascinating creatures. If they lived in my area, I’d probably keep them temporarily as pets to observe them further.

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