Feminine stereotypes

Male tarantulas, when they reach sexual maturity, are focused on wandering away to find sex, to the point where they may lose interest in eating.

Females, on the other hand, turn into voracious consumers of calories.

Blue wants her morning mealworm, and strikes like lightning.

I think Blue is a she

Blue is the lab mascot, a Chromatopelma cyaneopubescens, and after their last molt, they’ve acquired the dark blue and blue-green colors of a mature greenbottle blue tarantula, and maybe reached sexual maturity. I’ve been checking out those palps, and they look very feminine to me.

Let me know what you think.

Fortunately, Blue is a perfectly good name for a female. Or male. Or immature juvenile.

Spiders make art

My black widows were relocated to new empty cages, and overnight they filled them with beautiful, intricate cobwebs, like this one.

It looks chaotic, but I can trace a couple of gumfoot lines in there that have bracing to allow them to hoist up any prey that stumbles into them.

Blue has molted!

Today I’m catching up with lab work, and the first thing I spotted after coming through the door was that our tarantula, Blue, had molted overnight. I’ve been keeping their molts as a record of their growth.

Top left is the molt from this past summer; top right is the latest, looking a bit crumpled. Human skull in the frame as a size reference.

Blue is in the background. They look smaller because they’re farther away, but trust me, Blue has grown! Also, they’re a bit cranky because I don’t think their cuticle is fully hardened yet.

That’s how you get spiders, you know

I was feeding the black widows in my lab (all neatly caged, of course) when I saw this little guy hanging out just above the benchtop. Pholcus phalangioides, obviously.

I imagine most people have a little internal debate — do I squish him, or do I gently scoot him out the door? I always take the third option. I had just come from the genetics lab, with a bottle full of redundant Drosophila, and I shook a bunch out over her web. She was showered with flies! She was so excited, scurrying about to wrap them all up.

This is how I generally treat these random spiders in the lab (I call them the Ferals, and I’ve got Ferals all over the place.) I guess I shouldn’t wonder how she got here.

A spider with two hoo-has

Nice.

Almafuerte peripampasica, female. A, prosoma and opisthosoma (dorsal view). B, opisthosoma (ventral view, arrow pointing to the duplicated epigyne). Note the difference in size and the slightly asymmetry. C, normal epigyne (arrow pointing to larva). D, duplicated epigyne. Specimen locality: Argentina: Córdoba: Parque Nacional Quebrada del Condorito, “sitio 2”, -31.63481, -64.71087, alt. 1846m, M. Izquierdo, D. Abregú, C. Mattoni, col. Sep. 16, 2019, under stones. LABRE-Ar 498, voucher MAI-4754.

Developmental variations always catch my eye, and this one is interesting from the standpoint of looking for spatial specifications. The normal blueprint for the spider body plan puts the epigyne at the anterior end of the abdomen, but here’s one way back near the spinnerets. What triggered formation at that position? It’s also non-functional, they think — I’d want to know more about the internal organs, what’s connected to what.

In general, malformations in spiders involve chelicerae, pedipalps, walking legs, and eyes, but those affecting female reproductive structures are not so frequent. A teratological case of a spider with a duplicated reproductive structure is described. The female specimen has the typical epigyne and a second one near the spinnerets. The second epigyne is less developed and seems to be non-functional. Similar malformations have been reported for Amaurobiidae and Salticidae, and here is presented for Gnaphosidae. Although it is widely known that temperature and humidity may induce abnormalities under experimental conditions, the causes behind teratological genitalia in wild females are unknown. This case opens the question of the origin of such a malformation and the ontogeny of female reproductive organs in spiders.

Also, that’s an adult of respectable size, so the ectopic organ doesn’t seem to have affected its viability. I’m going to have to spend some time looking up spiders’ skirts this summer.