Cardiodectes bellottii

{{Short description|Species of crustacean}}

{{Italic title}}

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| taxon = Cardiodectes bellottii

| authority = (Richiardi, 1882)

| synonyms =

• Peroderma bellotti Richiardi, 1882
• Lernaeenicus medusaeus C. B. Wilson, 1908
• Cardiodectes medusaeus (Wilson, 1908)

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Cardiodectes bellottii is a species of copepods in the family Pennellidae. It is a parasite of fish. It is found in the Atlantic and Pacific Oceans as well as the Mediterranean Sea; specimens from the Pacific were formerly treated as a separate species, Cardiodectes medusaeus.

In the cnidarian Hydrichthys sarcotretis, parasitism is taken a stage further when the hydrozoan attaches itself to the C. bellottii. This is itself an ectoparasite of the northern lampfish (Stenobrachius leucopsarus) in the family Myctophidae. The copepod attaches itself to the bulbus arteriosus of the fish. Such a parasitic chain is known as hyperparasitism.{{cite book |title=Parasitism: the diversity and ecology of animal parasites |last=Bush |first=Albert O. |year= 2001|page=285 |publisher=Cambridge University Press |url=https://books.google.com/books?id=Q6Kl0FbvStoC&dq=Peachia+quinquecapitata&pg=PA287 |isbn=978-0-521-66447-9 }} C. bellottii requires two hosts for proper development. It will go through five successive postembryonic stages, then only the post-mating females will go into the pericardial cavity of a lanternfish.{{Cite journal|last=Perkins|first=Penny|date=1985|title=Iron crystals in the attachment organ of the erythrophagous copepod Cardiodectes medusaeus (Pennellidae)|journal=Journal of Crustacean Biology|volume=5|issue=4|pages=591–605|doi=10.2307/1548237|jstor=1548237}} The actions of the copepod castrate its fish host. Both male and female fish do not reproduce and seem to grow faster when attacked by the copepod and it seems to have a negligible energy demand from them.{{cite journal |year=1978 |title=Effects of the copepod Cardiodectes medusaeus on the lanternfish Stenobrachius leucopsarus with notes on hypercastration by the hydroid Hydrichthys sp. |journal=Canadian Journal of Zoology |volume=56 |issue=11 |pages=2372–6 |doi= 10.1139/z78-321|last1=Moser |first1=Mike |last2=Taylor |first2=Sam |bibcode=1978CaJZ...56.2372M }} The hydrozoan parasite castrates the copepod, a process called hypercastration.