title for learn-about section of A SNAIL'S ODYSSEY
  Feeding & growth
  There are many bacterial and fungal diseases of mussels that are known to affect growth and survival.  These have been well studied in the context of mariculture and will not be considered in the ODYSSEY.  Parasites of mussels include intestinal copepods and mantle cavity-inhabiting crabs that must also deleteriously affect growth and survival, but no studies have yet been done to test this.
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Effect of parasites on growth & survival

  Studies on effect of parasites on growth & survival are presented in this section, while topics of FEEDING, and GROWTH are considered in other sections.
pair of Pinnixa sp. crabs in the mantle cavity of a mussel Mytilus californianus
A pair of pinnotherid crabs in the mantle cavity of a sea mussel Mytilus californianus, possibly a smaller male and larger female Fabia subquadrata. The crabs enter a mussel as larvae or juveniles 1X
  photograph of a Pinnixa-crab in the mantle cavity of a mussel Mytilus californianus
Female pea crab Fabia subquadrata tucked within the gills of a mussel Mytilus californianus. Pea crabs feed on material filtered from the water by their hosts 2.5X
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Research study 1

photograph of copepod Mytilicola orientalis, a parasite of marine invertebrates including mussels Mytilus spp.The copepod species Mytilicola orientalis inhabits the intestinal regions of bivalves including oysters, clams, and mussels Mytilus spp.  A study on aspects of infestation in mussels Mytilus trossulus at the Bamfield Marine Sciences Centre, British Columbia shows that up to 80% of summer-collected mussels in sheltered habitats host the parasite.  No parasites are found in mussels from wave-exposed sites.  On average, only 2 copepods are present in each mussel, although large individuals living closest to the low tide mark may have 4 or more.  Why so few parasites per mussel and do their numbers reflect balanced sex ratios? The authors do not discuss this, but do remark on restricted distribution owing to limited transmission within sheltered, muddy estuaries.  Goater & Weber 1996 J Shellf Res 15: 681.

NOTE  both M. orientalis and M. ostrea may have been introduced to the west coast in shipments of oysters Crassostrea gigas from Japan

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