An example – Polymorphus spp. Acanthocephala



a diagram of life cycle of polymorphus spp.


polymorphus spp. parasites of seabirds, particularly eider duck (somateria mollissima). heavy infections of 750 parasites per bird common, causing ulceration gut, disease , seasonal mortality. recent research has suggested there no evidence of pathogenicity of polymorphus spp. intermediate crab hosts. cystacanth stage long lived , remains infective throughout life of crab.


the life cycle of polymorphus spp. occurs between sea ducks (e.g. eiders , scoters) , small crabs. infections found in commercial-sized lobsters in canada acquired crabs form important dietary item of lobsters. cystacanths occurring in lobsters can cause economic loss fishermen. there no known methods of prevention or control.








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