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 Post subject: Fishing Spiders
Unread postPosted: Thu Dec 29, 2011 7:01 am 
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Location: Johannesburg - where they cut down trees and name streets after them.
Subfamily: Thalassinae
Genera: Thalassius, Dolomedes

They hunt by waiting at the edge of a pool or stream, then when they detect the ripples from prey, they run across the surface to subdue it using their foremost legs, which are tipped with small claws; like other spiders they then inject venom with their hollow jaws to kill and digest the prey. They mainly eat insects, but some larger species are able to catch small fish.

Dolomedes spiders are covered all over in short, velvety hairs which are unwettable (hydrophobic). This allows them to use surface tension to stand or run on the water, like pond skaters. They can also climb beneath the water, and then air becomes trapped in the body hairs and forms a thin film over the whole surface of the body and legs, giving them the appearance of fine polished silver. Like other spiders, Dolomedes breathe with book lungs beneath their abdomens, and these open into the air film, allowing the spiders to breathe while submerged. The trapped air makes them very buoyant and if they do not hold onto a rock or a plant stem they float to the surface where they pop onto the surface film, completely dry.

The main predators of fishing spiders are birds and snakes. Dragonflies have also been observed catching young spiders. Species parasitic on the spiders include a wasp of the Pompilidae family that stings the spider to paralyse it before carrying it off and laying an egg in its abdomen. The larvae of the wasp hatch and proceed to eat the spider from the inside out. One escape technique the spiders use is to disappear beneath the surface tension of the water. However some wasps counter the disappearing trick by going into the water to sting the spider and drag them out of the water.

Female fishing spiders are larger than the males. If a female chooses to eat a male after mating, there is usually little he can do about it. This behaviour may help the female by providing the nutrition she needs to produce healthy young, while the male gets the benefit of passing his genes on to a well-fed next generation.
Source: Wikipedia

Thalassius spinosisimus
Image

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 Post subject: Re: Fishing Spiders
Unread postPosted: Thu Dec 29, 2011 7:40 am 
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Such interesting animals! :thumbs_up:

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