Wednesday, April 18, 2012

Giant fishing spider!

After spending all day last Saturday within the confines of a conference hall, I was more than ready to explore the great outdoors the following day. Don't get me wrong - the conference was fabulous and provided a goldmine of information - but I was near the iconic Shenandoah National Park in Virginia, and was eager to explore the place.

So, after spending Saturday night near the eastern slope of the Blue Ridge Mountains, it was in the car and up the mountain on Sunday morning. This shot was taken along the beautiful Skyline Parkway, which traverses the length of this 105 mile long, 200,000 acre park. Spring is slower to arrive at the mountain's summits, but there were still interesting flora and fauna, and breathtaking scenery at every turn.

What goes up must come down, and eventually it was time to drop down off the mountain. On the way down, I spied a beautiful rushing brook, and decided to explore its banks. A Louisiana Waterthrush, full of vim and vinegar, had staked out this stretch of stream and was loudly proclaiming his land rights by singing his way up and down the creek. Few bugs or buglike creatures are safe around these big warblers, but I suspect even the waterthrush would have given broad berth to the upcoming arachnid.

BRACE YOURSELVES, arachnophobes!

I found myself perched on a large streamside boulder, quietly gazing about, when a sudden movement near my feet caught my eye. You can only imagine my elation at glancing down to see this huge fishing spider sidling around the rock's edge! It isn't every day one of these eight-legged jumbos presents itself so readily for photos!

My Nikon had its 105mm macro lens bolted in place, and I began snapping away. There are a half-dozen or so fishing spiders in the genus Dolomedes in the eastern U.S., and I knew it was one of them. At first, I thought it was the six-spotted fishing spider, Dolomedes triton, as it too has that prominent white border around the upper body. But the animal lacked the spotting of that species, and after a bit of investigation I believe this spider is Dolomedes scriptus, which is one that I was not familiar with. As I can't find a common name for the beast, I suggest dubbing it the giant fishing spider.

I found her - it is certainly is a female given its massive size - to be quite showy, and I carefully watched her with my two eyes, and she in turn peered at me with her eight eyes. Either I was in her way, or she was curious about the stranger and emerged from her lair for a look. Could be a curiosity thing, as fishing spiders hunt primarily at night. It may be that I just settled too close to her den and she felt the need to investigate.

From leg tip to opposing leg tip, this spider was probably in excess of three inches. Despite the menacing appearance, she was rather tame and confiding, and like virtually all spiders is utterly harmless to people. By gently prodding her with a small twig, I was able to pose her in different ways for this photo shoot, and she offered no substantial objections.

Note the giant palps; the club-tipped "feelers" that resemble a fifth set of stubby legs and extend forward from the jaw area of the spider. She uses these as sensory organs, and you DO NOT want to be the sensed organism, if you are possible prey.

Fishing spiders are aptly named, as they are nearly always found around water bodies. The dense layer of hair which cloaks their body is hydrophobic, or water-shedding. These animals can deftly run across th water's surface without breaking the surface tension, like gargantuan murderous water striders. Fishing spiders can even dive under the surface, becoming encased in a silvery bubble of air when below.

Apparently a common hunting ploy has the spider anchoring itself to the bank with its rear legs, and gently floating its palps on the water's surface. The hypersensitive palps can detect motion on the water, and when a bug falls in the drink or perhaps swims by, the spider detects the movement and rushes out to grab the victim. Larger individuals, such as the one in these photos, can even take small fish and tadpoles.

I felt rather lucky, as it isn't every day one happens across such an extraordinary animal as this spider.


KaHolly said...

Wow! I don't mind spiders, but perhaps this one is a little big for me.

Lisa at Greenbow said...

What an amazing creature. I always learn something from your posts. I would love to see one of these creatures in person especially if it was in it's bubble.

Ron Gamble said...

I'm curious; seeing the "boxing gloves" at the end of the palps, particularly in the most close-up photo, I'm thinking this spider is male. Any thoughts?

Jim McCormac said...

Thanks for the comments, as always! Ron, I don't know of differences in the palps between the sexes, although there may well be. I was judging it to be a female based on size - the spider was a good three inches from leg tip to leg tip, and I didn't think males got that large.

jaredmizanin said...

..."imagine my elation"...haha! Only us nature-nerds would find joy in coming across a huge spider! Beautiful species...hope I bump into some myself.

spiders said...

Just adorable nature, so nice clear brown colours on that spiders, our planet is just beautiful!

Gerald said...

I see these spiders all the time on Captina Creek, Ohio. They kind of freaked me out at first, until I learned that they are harmless.