(Courtesy of Harold Wes Pratt)
Common Southern Comb Jelly, Sea Walnut
(Mnemiopsis leidyi)

These clear, colorless invertebrates aren't like jellyfish- they can't sting you because they don't have nematocysts (stinging cells). Some grow up to 4" (10 cm) long, but the ones you will commonly see are 2-3" (5-7.6 cm). They lose their tentacles as they grow up, but have two lobes that are attached near the top of their body and are longer than the body. They swim with their lobes outstretched then snap them closed when they encounter big prey, such as copepods. They have sticky cells that line the inside of their bodies (like fly paper) and help them capture small prey, such as the larvae of crabs and snails. These comb jellies produce a blue-green bioluminescent glow when disturbed. They are found in Narragansett Bay from May through December.

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