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Genus Margaritifera

Family Margaritiferidae



Formerly common in the Hackensack River and known from the Delaware River watershed, M. margaritifera today may be extirpated from the Hackensack River and is rare everywhere else in the metro area; it is apparently extirpated from New York State within the metro area, although still present in several other NY localities. It may remain common in restricted mountain stream habitats in the Appalachians (Strayer, 1994).

Species Summary

Species summary

Margaritifera margaritifera (Linneaus, 1758)
eastern pearlshell



beak: coarse, concentric sculpture
color patterns: no color rays
shape: elongate, sub-elliptical, ventral margin often arched dorsally
shell features: periostracum dark brown to black, series of small muscle attachment scars across a broad area of interior nacre
teeth: strong pseudocardinals, laterals absent


abundance: rare
status: US, NY, NJ: not legally protected; CT: special concern IUCN: endangered
conservation challenges: Absence of key host species in the lower Hudson River estuary may impact recovery of this species


N.A. distribution: New England maritimes to Connecticut, New York and Pennsylvania
present metro distribution: NY: not known; NJ: Hackensack River (lower Hudson River watershed); CT: Housatonic River watershed, Southwest coast watershed
other regional localities: NY: Hudson River watershed, Southern Adirondacks, northeastern Lake Ontario watershed, Oswego watershed, St Lawrence River watershed; NJ: not present; CT: lower Connecticut River watershed
historical localities: NY: Richelieu River watershed, upper Delaware River watershed; CT: Thames River watershed, South central and Southeast coast watersheds


Life History:

habitat: cold, nutrient-poor, soft-water streams with moderate to fast flow; substrate fine, firm sand, gravel or cobble Habitat Photo
hosts: Hucho hucho (Linneaus, 1758) huchen; Oncorhynchus clarki (Richardson, 1836) cuthroat trout; Oncorhynchus kisutch (Walbaum, 1792) coho salmon; Onchorynchus nerka (Walbaum, 1792) sockeye salmon; Onchorynchus tshawytscha (Walbaum, 1792) chinook salmon; Onchorynchus mykiss (Walbaum, 1792) rainbow trout; Phoxinus phoxinus (Linneaus, 1758) Eurasian minnow; Rhodeus sericeus (Pallas, 1776) bitterling; Salmo salar (Linnaeus, 1758) Atlantic salmon; Salmo trutta (Linnaeus, 1758) brown trout; Salvelinus fontinalis (Mitchill, 1814) brook trout


M. margaritifera

Left view

left view

Right view

right view

Dorsal view

dorsal view

Profile view

profile view


nacre whitish, with pores

Beak sculpture

beak sculpture with coarse concentric sculpture


pseudocardinals strong, laterals absent

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