Halloween ID challenge

Class and order are gimmes – can you name the family, genus, and species? Common name? Something significant about its biology or behavior?

Photographed 25.ix.2010 in shortgrass prairie habitat atop the Pine Ridge in Sioux Co., Nebraska.

Photo Details: Canon 50D w/ MP-E 65mm 1-5X macro lens (ISO 100, 1/250 sec, f/11), Canon MT-24EX flash w/ Sto-Fen + GFPuffer diffusers. Typical post-processing (levels, minor cropping, unsharp mask).

Copyright © Ted C. MacRae 2010

6 thoughts on “Halloween ID challenge

  1. Definitely an Argiope species based on the way the legs are held paired up. I almost said A. aurantia, but the legs aren’t right. So I’ll go with A. trifasciata, the banded garden spider.

    Intreresting tidbits: These spiders create a stabilimentum in their webs, the purpose of which is probably to make the web more visible and to discourage birds from flying through it and destroying it (there are alternative explanations as well). They don’t remake their web every evening like most other large orb weavers, and stay in it during the light of day.

  2. I’ll go with Troy – from the St Andrew’s Cross leg arrangement, the pair of yellow ventral stripes, and the central black stripe with paired white spots – I’d guess Argiope. Both trifasciata and aurantia are common in Nebraska according to the University of Nebraska Lincoln webpage (well, assuming their common names are the same as BugGuide – I wish theyed included the binomials). The only thing that bothers me is the weak spotting on the legs, but leg bands seem variable. I guess since Troy already picked trifasciata, I should go with aurantia.

    Large, brightly coloured spiders that sit in permanent webs like Argiope and Nephila species must aposematic – although I have watched birds eat Nephila edulis (which sounds tasty).

    One of the alternative hypotheses for stabilimenta is that they are sponges for accumulating water for the spider to drink. I’ve seen some data suggesting that stabilimenta are more common and larger in exposed compared to sheltered locations that is consistent with that hypothesis. Also, under the SEM they do look sponge-like. But then, no reason you couldn’t kill two birds with one sponge.

    • I’ve always wondered whether the coloration actually represents aposematism or if it is just assumed, as the spiders always seemed difficult to to see in the field. One recent study of an Australian species suggests that the main function of the coloration is for crypsis through disruptive coloration to obscure the outline of the spider, while another in the UK supported the hypothesis that it acts as a visual lure for insect prey and found little support for the crypsis hypothesis. So – who knows?


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