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Winter Spiders

katemacquarrie22

Welcome back to Ask a Naturalist, your own personal Google for information on all things natural on PEI! Today’s topic is courtesy of Chris Collier, who sent me this photo of a lovely green spider, one of about 20 he saw on top of the snow in his driveway recently. Meet the Green Long-jawed Orbweaver (Tetragnatha viridis).


A Green Long-jawed Orbweaver in January on Prince Edward Island
A Green Long-jawed Orbweaver in January on Prince Edward Island

If you think the lack of insects, spiders, and other creepy-crawlies is the best thing about winter on PEI, I have bad news for you: it’s not unusual to see some of these animals around even in the coldest months. You may be familiar with Snow Fleas (aka Springtails, a type of Arthropod), but many invertebrates have adaptations that allow them to be active when temperatures drop below freezing.

 

But let’s start with this spider’s name. The green part is obvious and one reason why this species is most commonly spotted in winter. Green Long-jawed Orbweavers hang out in and around our coniferous forests, and blend in well among the needles of Spruce, Pine, and Fir. When not moving, they’ll extend their front legs ahead and rear legs behind, stretching out to look a bit like a conifer needle, adding to their camouflage. But once the snow hits, the Green Long-jawed Orbweaver’s verdant exoskeleton becomes eye-catching against the white background.

 

‘Long-jawed’ sounds ominous but remember that size is relative: this is a tiny spider, less than half an inch (12 mm) long. The mouthparts (technically called chelicerae) of Long-jawed Orbweavers are comparatively longer than those of other spiders, and longer than the front part of the body (the cephalothorax), but not long enough to do us any damage.

 

Finally, there’s Orbweaver. This is the name for a Family of spiders characterized by their circular (orb-shaped) webs; it includes the common black and yellow Garden Spider (Argiope aurantia) that many people are familiar with. The Green Long-jawed Orbweaver was once a member of this Family, and although it’s been reclassified it has kept ‘Orbweaver’ as part of its common name.

 

So, how do these tiny green arachnids survive winter? Thanks to a few useful adaptations. First, Green Long-jawed Orbweavers take advantage of the subnivean zone – the area between the ground and the snowpack. The insulating properties of snow keep this zone at or just above 0C (32F) even in the coldest temperatures and provides protective cover from wind and storms. This is prime real estate during an Island winter and a variety of spiders, insects, and small mammals spend the season here.

 

Next, Green Long-jawed Orbweavers and other spiders can enter a type of dormancy called diapause, reducing their metabolic rate and conserving energy during the winter. And lastly, cold weather triggers these spiders’ bodies to start producing an antifreeze (glycerol) which enables them to survive temperatures below zero without freezing. Some of our frogs also use this strategy, and our trees use sugar and proteins the same way.


On winter days with temperatures near or above 0C, Green Long-jawed Orbweavers may venture out in search of a snack, with the aforementioned Snow Fleas being high on the menu. While spiders are certainly more common in warmer seasons, it's not unusual to see them in winter. As our winters become milder, I suspect this season will be less and less of a refuge for arachnophobes, but Spiders and their cool adaptations are all part of PEI Untamed!

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