Lake Water Quality - freshwater jellyfish

This is a close-up picture of a Secchi disk, but more interesting is the nickel-sized, whitish-transparent blob. The blob is one of the freshwater jellyfish  (Craspedacusta sowerbyi) that were seen in Lake Thomas (Stevens County) a few years ago. These creatures are quite rare. They hide out for years in a different form in the sediments of a few lakes and reservoirs, only occasionally producing the small but classic jellyfish form (barely) seen here.