The Atavism

Sunday, January 31, 2010

Sunday Spinelessness - Motherly Devotion

I promised last week that I'd come up with something a bit more cheery than photos of dead flies for the next Sunday Spinelessness post and what could be more uplifting than portraits of motherly devotion? Of course, in this case the mother is a spider. The New Zealand lynx spider Oxyopes gracilipes.

Gravid Lynx Spider

Lynx spiders are a family (Oxopidae) of very active and fast running hunting spiders. The swollen abdomen of the female photographed above is evidence of her gravidity (I was tempted to dedicate this post to Harvest Bird who finds herself in the same condition but I'm not quite sure how someone a little less arachnophilic than I would take that). A few days before I spotted the gravid female I'd taken some pretty poor photos of a male lynx spider on the same plant so we can probably assume he's the father.

LynxM

And because that photo really is pretty awful here's another male lynx spider I found crawling around on our house

lyncM2

That's a bit more like it. In this one you can see a few of the defining morphological characteristics of the lynx spiders - spiny legs, a hexagonal arrangement of eyes very large and palps in males. O. gracilipes also displays a few behavioral traits that are typical of lynx spiders, it's active during the day there is a great deal of maternal investment in offspring. Here's our female again, a little over a week after the first photo.

lynxF2

She's lost her former globose shape because she's laid her eggs. The silk she's spun around the leave is protective egg sag but lynx spiders take protection very seriously - they won't leave the fate of their eggs to a bit of silk and chance. I checked on the egg sac almost every day for two weeks and never found the lynx spider more than a few centimeters away. Little is known about the behaviour of our lynx spider but their American counterparts have been known to relocate egg sacs when they are threatened by predators or starve to death while standing guard. In the end I had to leave before the spiderlings hatched but in Spiders of New Zealand and their Worldwide Kin Ray and Lyn Forster tell us that the female wanders off shortly before that event.

As ever you can click on the images to get to a higher resolution version.

lynxF3

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Posted by David Winter 9:14 AM

2 Comments:

I am an enthusiast for the presence of spiders and enjoy having them round the house to the extent that I feel guilty when occasionally I vacuum abandoned webs from the ceiling! So to be compared in both form and function to the gravid lynx spider is very pleasing, although I probably shouldn't be too interested in the part of the story where the mother departs her eggs prior to hatching.
Oh Good! I find it's safer to assume everyone else is, if not arachnophobic, then not on the spiders' side.

The relatively helpless nature of human offspring (when compared with chimps and goirllas rather than spiders) is actually a topic of consideration among primatologists.

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