May 14, 2009
By Susan Benson,
CNHM Director of Education
We all know the song “head, shoulders knees and toes, knees and toes.” Well, I sing a different version of this song about insects – “Head, thorax, abdomen, abdomen.” First graders in many of the area schools get to sing and learn about insects when I visit their classrooms in the spring as part of the Museum’s MuseumMobile program. Previously we had studied spiders, so first graders in this region are equipped to identify the differences between arachnids and insects. This week in Drummond, we went outdoors to catch insects or spiders in the school forest. One of the highlights of our explorations included the very “cool” jumping spiders. Jumping spiders are truly amazing spiders for many reasons.
A jumping spider’s family name is Salticidae, whose roots come from the Latin word saltare, to jump or dance. Jumping spiders are daytime hunters. Thought to have the best eyesight of most invertebrates, they are well designed to hunt their prey. Using their keen sight, they run toward their prey, slow down, and then stalk as they get closer. A silk dragline is attached to the ground before they jump so they can move to a safe place afterwards. When jumping, they have a hydraulic-like system – by altering the pressure of their body fluids, they can jump without needing muscular legs. With this technique they can jump from 20-80 times the length of their body. In comparison, I would have to be able to jump 433 feet!
When they are not hunting, jumping spiders maintain woven homes for resting and hibernating that are located under stones, bark, or in leaves. Having no local shopping centers to find their food, they must search anywhere and still be able to return to their home. In lab tests, jumping spiders were presented with prey and artificial branches arranged so that the predator had to walk around the obstacles to get to the prey. The spiders were able to scan the “maze”, move in a pathway around the obstacles, rescan the maze, and find the prey. This experiment showed some evidence of memory or intelligence in a small creature with what we would say is a very tiny brain. Without creating a mental map, how else could the spiders have set out a path away from their prey and still had a successful hunt?
Animals of any shape or size can continue to amaze us. Next time you are out for a walk, step slowly through your lawn, or through a meadow to observe the jumping spiders near your home. Or perhaps while sitting on the ground in the sun, you’ll see one approach, jumping lively or maybe looking at you “curiously” with its keen eyesight. Jumping spiders are just one of the animal species with mind-boggling abilities.
Nature Watch is brought to you by the Cable Natural History Museum. For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility and exhibits, the Curiosity Center and Brain Teasers 2, in Cable at 13470 County Highway M. Also find us on the web at www.cablemuseum.org to learn more about exhibits and programs.