Observation of the Week, 1/26/18

Our Observation of the Week is this Celaenia excavata spider, seen in Tasmania, Australia, by @simongrove!

Simon Grove is all about sharing. As the Senior Curator of Invertebrate Zoology at the Tasmanian Museum and Art Gallery (TMAG), Simon’s main duty is to care for the museum’s collections, but he says “I'm also interested in outreach, which is one reason I take photos of living insects and spiders.” Not only does he post them on Flickr (and is currently importing his Flickr photos to iNat), he shares them on two Facebook Groups and his own Facebook page as well as on the TMAG’s A Field Guide to the Fauna of Tasmania mobile app. “It's also one reason I signed up to iNaturalist, in that I can help identify or validate others' Tasmanian nature observations,” he explains.

Oh, and

My 'research-grade' observations on iNaturalist, and the accompanying photos, will also find their way onto our national recording platform, the Atlas of Living Australia, where the photos will help others identify their own observations while the observations will augment museums' specimen-based records in helping us better understand what lives where around Australia.

The Celaenia excavata spider you see above is one of Simon’s older photos that he recently imported from Flickr. He found in April of 2015, sitting on a ripening almond at a community garden in Taroona. “It's a common species in suburban Hobart and elsewhere in Tasmania and southeast Australia,” says Simon, “but seldom spotted because of its close resemblance to a dollop of bird poo.” During the day, this spider rests and hides, utilizing its camouflage as protection, but at night it preys on moths, especially those commonly found in orchards.

But how does this tree-climbing but non-web-spinning spider capture its prey? Well, Simon says “[they] waft chemicals into the air which mimic the pheromones of female moths. When a male moth comes to investigate the source of the smell, the spider has a chance of grabbing it.” You can see another iNaturalist observation showing a Celaenia excavata eating a moth here. The myriad ways in which spiders have evolved to capture prey is astounding.

Here’s to more amazing observations from Simon’s archive!

- by Tony Iwane


- Bolas spiders also look like bird droppings (or snails) and use pheremones to draw in moths. However they use a “bolas” made of silk and glue to catch their prey. Check it out!

Posted by tiwane tiwane, January 26, 2018 09:31 PM

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