Animals throughout the world are divided into two major groups – those that possess a backbone (vertebrates) and those that do not (invertebrates). These groupings are based largely on tradition and convenience rather than natural biological differentiation. Invertebrates constitute about 95% of all described animals with nearly one million of those being insects (refer to the Insects webpage).

Examples of more visible invertebrates at Shenandoah, other than insects, are earthworms, ticks, millipedes, and Daddy-long-legs or harvestmen spiders. Some will encounter evidence left behind by these organisms – the spider’s web or the mucus trail of a land snail or slug. Unfortunately, virtually no studies of these animals have occurred at Shenandoah. Numbers of species simply are not known.

Invertebrates are found in most habitats including the depths of the oceans and on glacial ice. Like insects, invertebrates serve various important ecological roles including consumption and reduction of organic matter, decomposition, and as a food source.

Websites that provide photographs and helpful biological information about invertebrates include the following:

Discovery – All About Earthworms

Iowa State University Image Gallery – Ticks

New York State Department of Environmental Conservation Key to Aquatic Macroinvertebrates

Listing of these websites does not and is not intended to imply endorsement by the National Park Service of commercial services or products associated with the sites.