Elliptio crassidens

Diagnostics 3


  • size: med-sized to very large. maximum 150 mm, most specimens under 100 mm
  • thickness: thick to very thick, solid and heavy
  • shape: variable. triangular to somewhat elongate, posterior end pointed and posterior ridge pronounced and curved downwards, with narrow posterior slope. ventral margin straight to lightly concave. 'hunched forward' appearance common, due to more pronounced shell growth in posterior ventral edge than anterior ventral edge, causing older ventral growth lines to form an acute angle with more recent ones. posterior end sometimes hooked ventraly in older individuals
  • width: moderate to inflated
  • surface: rough to very rough
  • beaks: relatively flat to slightly elevated, often dissolved/eroded in most adults. sculptures; 2-3 coarse loops, rarely present.
  • color/markings: brown to very dark brown or black
  • sexual dymorphism: none
  • Hinge/teeth: very strong/heavy to massive, striated pseudocardinals. laterals strong/thick. interdentum very wide and thick/full
  • nacre: purple, pink or white

Soft parts: foot white

Similar species/lookalikes: typical-shaped live specimens usually easily identifiable, but more elongate-shelled animals can resemble eastern Elliptio and Spike. empty shells of typical shape readily identifiable by uniquely massive dentition and thickness, but all these features can be much less obvious in many specimens, as a wide range of intermediate forms with those two taxons can be quite common in some localities such as the the Ottawa and Saint-Lawrence drainages in the Greater Montreal Area. Eastern Elliptios, whether elongate or compact-shelled, usually show proportional, harmonious growth lines, causing ventral margin lines to be relatively parallel, not angled. Canadian specimens are usually much smaller than their Mississippi drainage counterparts.

Sources and Credits

  1. (c) Philippe Blais, some rights reserved (CC BY-NC-ND), uploaded by Philippe Blais
  2. (c) Femorale, some rights reserved (CC BY-NC), http://www.femorale.com/shellphotos/detail.asp?species=Elliptio%20crassidens%20(Lamarck,%201819)
  3. Adapted by Philippe Blais from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Elliptio_crassidens

More Info

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