Wednesday, February 20, 2008

The White Tent The Raft

It’s been a while since an arachnid has graced this blog, and since I only have three arachnid posts total, it’s high time I add to it1. Everyone keeps calling it “one of Europe's largest, most beautiful but least common species of spider.” Hate to break it to you guys, but it’s still a spider, and most people don’t like spiders.

Image by Helen Smith
Image by Helen Smith. Yeah, I think it’s pretty too. But look how surprised that fish is!
The Fen Raft Spider (Dolomedes plantarius) is not an aquatic spider--there’s no such creature2. However, they aren’t aquatic in the same way a Water Strider isn’t aquatic. Just because you can’t swim doesn’t mean you have to get out of the pool—or rather, off the pool. They skate on top, using surface tension to float across the bogs and swamps; hence the name “Fen Raft”.
These spiders are found throughout in wetlands throughout Europe, with a fairly spotty distribution. They do not build webs to hunt, preferring to wait on a stem with their front legs touching the water’s surface. When they feel a vibration, BAM! Dinner is served. Main courses typically include aquatic insects, water striders, and less frequently, fish, like our surprised friend shown above.

The water also comes in handy when a male Fen Raft Spider wants to woo the ladies. Courtship involves drumming the water until the couple meets, when they both begin to bob slowly to each other. Mating is quick, likely because it is not unheard of for the male to become a protein source. After laying the eggs, the female carries the egg sac under her fangs for about three weeks. After hatching, the young spend a week growing up in a web-nest that’s constructed and guarded by mom.

It seems that wetlands are disappearing everywhere, and therefore, so are the Fen Raft Spiders. The remaining wetlands are getting more and more pollution problems, and all evidence suggests that these spiders require clean water. There’s certainly hope though. Britain has pulled out all the stops trying to protect their two populations from dying out, and frankly, it seems to be working.

1Here’s a challenge for you readers: can somebody find me an endangered whipscorpion? That would be cool.
2These are not spiders.


Drew said...

You have confused me with your double asterisk! What is the antecedent to "These" in the phrase "These are not spiders."?

Garfman said...

There is no such thing as an aquatic spider. The animals I linked to are called "Sea Spiders" but are more formally known as Pycnogonids. They are arachnids, but not spiders.

Anonymous said...

First off...these things freak me out ((shudders)) but here is a species listed as "sensitive" by the BLM in California:

Shoshone Cave whip-scorpion
Trithyreus shoshonensis

Here is the link to their list (it is on the very last page):

Rainstorm said...

Oh my god, it's so incredibly ugly I could cry.

But I want to own one.

This is Kat, btw. :D I'm starting from here and will probably comment on others as I read backwards through the entries I still haven't read.

Anonymous said...

I watched quite surprised as a Fen Raft spider dined on a 10mm long fish in my pond today. It's the first time I have observed this behaviour from spiders. I'm in Port Vila, Vanuatu

Revereche said...

What about the diving bell spider?