Symbioses: parasitism
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  Research study 1

photographs of copepod parasite Ptilosarcoma athyrmataIn the first published report on this topic for sea pens Ptilosarcus gurneyi, a research group primarily from Hofstra University, New York describes a new species of copepod parasite Ptilosarcoma athyrmata (F. Lamippidae) inhabiting the rachis leaves. Male and female adult copepods may live in galls together (36% of galls studied) or separately (51%), with up to 100 or more galls photographs of sea pens Ptilosarcus gurneyi infected with copepod parasites Ptilosarcoma athyrmatainfesting a single sea-pen colony. Infestation intensity varies with habitat, reaching 75-100% in areas of Puget Sound, Washington. The authors classify Ptilosarcoma as an obligate endoparasite. As welcome as this morphological and taxonomic information is, much more needs to be investigated. For example, how and when the parasites gain entry to the host, how galls are formed, and how the parasites gain their own nutrition would be useful questions for future research. Buccal cones and maxillipeds are present in both sexes, but whether mouths function for feeding or nutrition gained by absorption from the host's body fluids, is not known. Williams et al. 2016 Mar Biodiv doi:10.1007/s12526-016-0593-z. Copepod e-micrographs courtesy the author; sea-pen photographs courtesy Neil McDaniel, a pre-eminent underwater photographer in British Columbia for the past 5 decades and one of the co-authors of the present paper NEIL McDANIEL

NOTE an early study on P. gurneyi at Hopkins Marine Station, Pacific Grove, California makes no mention of copepod-induced galls, so perhaps the parasites are restricted to more northerly latitudes as suggested by the present authors. Nutting 1909 Proc US Nat Mus 35 (1658): 681


Sea pens Ptilosarcus gurneyi infected with
copepod parasites Ptilosarcoma athyrmata

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