The large (to 75 cm diameter and about 25 kg) scyphomedusa, Drymonema dalmatinum, is reported for the first time in the Caribbean Sea. Many of these medusae were observed in shallow water in the Virgin Islands, as well as along the coast of Puerto Rico. D. dalmatinum feeds
mostly on Aurelia aurita medusae, and can consume several of these at the same time. Extracellular digestion occurs within the oral arms of D. dalmatinum which apparently secrete proteases; gastric cirri are absent in large specimens. The oral arms are massive, comprising ∼50%
of the total weight of the medusa, and have a surface area of several square meters in large specimens. The large size of the oral arms allows for gorging of prey when the latter are abundant. Laboratory-measured growth efficiency was low (3–5%). In situ observations of D. dalmatinum
showed that juvenile pelagic fishes are often associated with these medusae. Off Puerto Rico, an estimated 500 fishes, mostly Chloroscombus chrysurus, with fewer Caranax fusus, were seen swimming around one 75 cm diameter D. dalmatinum medusa. This species probably serves
as an important refuge for young pelagic fishes.
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