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Spider Egg Sac

Posted on April 12, 2011 by Troy Bartlett

If like me you occasionally flip over rocks and such to see what might be lurking beneath, then you’ve no doubt seen things like this:

6mm | January 19, 2011 | Armonia Nature Preserve, Limon Province, Costa Rica

I’m pretty sure this is the egg sac of some sort of spider. It was underneath a small rotting log.

I usually just carefully put things back the way I found them. Curiousity got the better of me this time. I peeled away the egg sac and carefully opened it. If you’ve ever wondered what’s inside, here’s the answer.

Eggs

Each one of those eggs are less than a millimeter in diameter. There were probably ten or so. read more

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Golden Silk Spiders, Mating

Posted on March 31, 2011 by Troy Bartlett

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

When I first spotted this female Nephila clavipes, she was positioned rather low in her web. Her background was cluttered and shaded. I prodded her a few times, and as I’d hoped, she retreated to a higher position in her web where I thought I might be able to get a more pleasing background.

Unexpectedly, her quick movements drew the attention of a male that was also hanging out in her vicinity. I’ve read that males prefer to mate when the female is preoccupied with a meal (so they’re less likely to become a meal themselves). Perhaps he mistook her quick retreat as movement toward prey. At any rate, he wasted no time approaching her and getting into a mating position. read more

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Golden Silk Orbweaver

Posted on March 27, 2011 by Troy Bartlett

January 18, 2011 | Gandoca-Manzanillo NWR, Limon Province, Costa Rica

I’ve never quite been happy with any of the photos I’ve taken of this species, Nephila clavipes. This photo is no exception. I do like that it captures the gold color of the web, and that at least a few of the leg tufts are in focus.

It’s a shame the spider lost a leg somewhere along the way. The missing leg distracts me every time I look at her.

These spiders really are quite large. This one measured around 30mm, 70mm if you throw in the legs.

See if you can spot the little fly that’s perched on her abdomen. read more

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Immature Argiope

Posted on March 8, 2011 by Troy Bartlett

January 18, 2011 | Gandoca-Manzanillo NWR, Limon Province, Costa Rica

Closeup crop

Argiope spiders are easy to recognize. They sit head down in the center of their webs with their legs paired up. They don’t even bother to hide themselves during the day. They are among a relatively small number of orb weavers that add a decoration to their web, called a stabilimentum.

The form of the stabilimentum may change as the spider grows. Young spiders like this one may create a dense circular pattern as shown here. Older spiders are more likely to create sparser designs in various shapes. read more

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Alpaida species?

Posted on February 21, 2011 by Troy Bartlett

5mm | January 17, 2011 | Cahuita National Park, Limon Province, Costa Rica

One of my books (below) has a picture of a very similar looking spider identified as a spiny flag spider, Alpaida cornuta, also from Costa Rica. I wasn’t able to find anything online though using either the common name or the scientific name. The World Spider Catalog doesn’t seem to recognize that name at all, but I saw two species there from Costa Rica, A. bicornuta and A. championi. Perhaps this is one of those.

Here’s a similar looking unidentified Alpaida from Ecuador, so I think the genus is probably correct. read more

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Identification Challenge #8 Reveal

Posted on February 5, 2011 by Troy Bartlett

15mm | January 17, 2011 | Cahuita National Park, Limon Province, Costa Rica

I knew the photo above would be difficult to identify, but I was happy that everyone at least figured out it was a spider. As a side note, I hope everyone realizes you can click on the photo to see a larger version.

One commenter, biozcw, ventured that it might be an Argyrodes species. That’s close, because the species I believe I have here, Ariamnes attenuatus, was formerly placed in that genus.

This spider was hiding beneath a large leaf. At only 15mm as shown in the initial photograph, it’s small and virtually disappears when assuming that cryptic position. Here’s a decidedly more spider-like pose. You can just barely see a strand of silk stretching from the spinnerets towards the upper right corner of the image. read more

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Silver Argiope with Wasp Prey

Posted on November 20, 2010 by Troy Bartlett

January 27, 2010 | Caraça Natural Park, Minas Gerais, Brazil

This spider was on an exposed ridge overlooking the sanctuary. She appears to have caught a nice sized wasp.

This species often creates an X-shaped design (stabilimentum) in their web, and you can just see a hint of one extending to the lower right.

The common name Silver Argiope is consistent with the scientific name (argentata = silvery). Even the common name in Portuguese, Aranha-de-prata, translates as Silver Spider. It is indeed silvery.

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Orb Weaver

Posted on November 6, 2010 by Troy Bartlett

January 27, 2010 | Caraça Natural Park, Minas Gerais, Brazil

This orb weaver was safely tucked away inside a leafy retreat.

The general shape puts me in mind of Acanthepeira species here in the US. There is at least one species, A. labidura, in Brazil. I couldn’t find any information on it though.

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Dueling Salticids

Posted on August 17, 2010 by Troy Bartlett

Standoff | January 26, 2010 | Caraça Natural Park, Minas Gerais, Brazil

I first spotted just one of these male jumping spiders. As I prepared to take some photos, it became aware of another male nearby. They approached one another and were obviously sizing each other up in preparation for a fight. Neither backed down, and so the fight was on.

Fight!

I like how they raise their pedipalps like boxing gloves. Or maybe that’s just to keep them away from the others fangs? Which would you bet wins this bout?

Knockout!

According to the timestamps on my images, they fought for around seven minutes. It looked like the object was simply to dislodge the opponent and send them tumbling away. You can see how they are using their long front legs to try and grab the other’s hind legs and pull them out from beneath each other. This is the knockout shot, as the one on the left has succeeded in grabbing the right one’s hind leg and right after pushed it off the leaf. read more

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Trechaleid Spider with Young

Posted on July 19, 2010 by Troy Bartlett

The first thing I photographed after arriving in Caraça Natural Park was this hunting spider, found wandering in an unpaved parking area.

Trechaleid Spider with Young | January 25, 2010 | Caraça Natural Park, Minas Gerais, Brazil

Up until I started preparing to write this post, I figured this was a wolf spider. After reading to learn more about the parenting behavior shown here, I’m now convinced it is instead a species in the family Trechaleidae. What first tipped me off was a similar photograph in this little book:

[book:0060849746]

Several identifying characteristics are mentioned for the particular species pictured. After some online searching, most appear to be shared by other species of the family. read more

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