Palpimanoid Spiders
 
Hannah Marie Wood
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    Palpimanoid spiders possess traits, like strange morphologies, restricted distributions, unusual predatory behaviors, low dispersal ability, and a fossil record, that make them an important and fascinating group for scientific research. In addition these small creatures inspire curiosity, awe and creativity. Currently five families belong to Palpimanoidea: Archaeidae, Huttoniidae, Stenochilidae, Palpimanidae, Mecysmaucheniidae. My current research focuses mostly on archaeids and mecysmaucheniids.
 

Mecysmaucheniid SpiderFemale mecysmaucheniid spider from Nahuelbuta Parque Nacional, Chile. (Mecysmauchenius sp.)

   Mecysmaucheniid spiders, also called trap-jaw spiders, are found in New Zealand and southern South America. These spiders seem to prefer cold, montane habitats and can be found in leaf litter and moss on the forest floor. Mecysmaucheniids have evolved a highly unusual way of capturing prey: when close to potential prey they hold their long chelicerae (jaws) out and open until the prey is close enough and then the chelicerae snap closed. A high-speed jaw mechanism has evolved independently several times and allows some lineages to close their chelicerae much faster than muscles alone could achieve. In most lineages this movement can be examined by using a high speed camera and recording at 20-30 thousand frames per second. However, in the New Zealand lineages, even when recording at 40,000 frames per second, the movement is too fast to be observed!

   

Archaeid Spider
Female archaeid spider from Nosy Be, Madagascar. (Eriauchenius gracilicollis) Photo by J. Miller

   Archaeid spiders, also called pelican spiders, were first discovered as Baltic Amber fossils in the 1800's. It wasn't until 30 years later that these spiders were found living in the forests of Madagascar. Restricted to small habitats in the southern hemisphere, the living lineages occur only in Madagascar, Australia and South Africa. Fossil lineages are known from Baltic and Burmite amber and from Mongolian shale. The bizarre appearance of these spiders illustrates the power of evolution. In most spiders the cephalothorax is a rounded plate, but in these spiders this plate and the chelicerae (jaws) are greatly elongated giving the spider the appearance of a 'neck' and 'head.' There is a huge amount of variation in the shape and length of the 'neck.' Archaeids are obligate araneophages, meaning they will only prey on other spiders. In this image the archaeid spider has just captured another spider and is holding this prey away from its body on one extended chelicera; this insures that the prey will not cause injury to the archaeid spider.

 
Contact Information

Hannah WoodHannah M. Wood

University of California, Davis
Evolution and Ecology
2320 Storer Hall
One Shields Avenue
Davis, CA 95616


hwood@ucdavis.edu