Mountain State Jellyfish Overview

Many of us have had a visit to the beach spoiled when a school of jellyfish floats in from the ocean, threatening swimmers with painful stings. West Virginia has no saltwater, but it does have a freshwater jellyfish.

The freshwater jellyfish is generally seen swimming along near the surface of lakes and slow-moving streams. The free-swimming or medusae stage of this jellyfish is not commonly observed because it is only about the size of a nickel, nearly transparent and only appears periodically in the late summer or early fall.

A medusa is shaped like an umbrella, with 50 to 500 tiny tentacles attached to its rim. It swims along in a dancing sort of movement produced by varying contractions of the umbrella. The tentacles contain no stingers but are used to sweep up tiny aquatic organisms suspended in the water.

Researchers have learned that freshwater jellyfish may live undetected for long periods of time as small, inconspicuous, bottom- dwelling animals called hydroids. Sporadically and unpredictably, the hydroids develop buds which are released to develop the free swimming medusae. Freshwater jellyfish are a simple form of life, but their complex life cycle and unusual appearance contribute to the wonderful diversity of plants and animals that inhabit the Mountain State.