Subject: Pond Pupa?
Geographic location of the bug: Connecticut
Time: 03:05 PM EDT
Your letter to the bugman: Good afternooon,
These little guys move with a jerking movement, are about 2mm in length, inhabit the water about 6-18 inches below the surface and are so numerous that it’s hard to believe.
How you want your letter signed: Dylan
These are freshwater Crustaceans in the genus Daphnia, commonly called Water Fleas because of the way they move through the water in a “jerking movement.” Daphnia are a common live food used by many enthusiasts to feed aquarium fish. You can find matching images on An Image-Based Key to the Zooplankton of North America and there is a nice drawing on Researchgate. According to the National Center for Biotechnology Information: “The genus Daphnia includes more than 100 known species of freshwater plankton organisms found around the world … They inhabit most types of standing freshwater except for extreme habitats, such as hot springs. All age classes are good swimmers and are mostly pelagic, i.e., found in the open water. They live as filter feeders, but some species may frequently be seen clinging to substrates such as water plants or even browsing over the bottom sediments of shallow ponds. Adults range from less than 1 mm to 5 mm in size, with the smaller species typically found in ponds or lakes with fish predation. The ecology of the genus Daphnia may be better known than the ecology of any other group of organisms.”