| from the June 7, 2009 Newsletter, issued from the
Siskiyou Mountains west of Grants Pass, Oregon: EARTHWORM ESTIVATION When the soil gets very cold, very hot, very wet or very dry, it's hard on an earthworm. Survival strategies vary from species to species. A typical behavior is to tunnel deeper into the soil to where conditions aren't so extreme. Some species, especially during hot, dry periods, do what's shown below:
At a fair depth they roll themselves into balls and excrete mucous around themselves creating a kind of cocoon. In such a state their body functions slow down drastically. They go into a kind of suspended animation, waiting for soil conditions to improve. When an animal enters such a state enabling it to survive summer's hot, dry conditions it's said that it estivates or "goes into estivation." This week I found the earthworm shown above as I worked in very dry, hard-caked garden soil. The earthworm lay inside a solid clod that broke apart like a brick. While the picture was being taken the worm began moving and I felt bad for having disturbed his dry-season repose. |
