Small, Shrimp-like Zooplankton



These small crustaceans have two long, distinct anntenae and make up the majority of zooplankton found in Delaware Bay and the mid-Atlantic.  They are holoplankton, meaning they remain planktonic for their entire lives.  Most copopods feed on phytoplankton and small bacteria, but some are raptorial and feed on smaller crustaceans.  All are key food sources for small fish throughout the estuary.  Above are some common copopod species for Delaware, and below short video of copepods in action. Can you identify the copepod species in the video?



These animals are related to the freshwater zooplankter Daphnia (water flea), but are generally smaller.  Like copopods, they are also holoplankton, spending their entire lives swimming in the water column.  Cladocerans feed on phytoplankton, including diatoms and dinoflagellates.  Interestingly, they brood their young within their carapace and have no free-swimming larvae.