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Elephant Ear (Elliptio crassidens)


Overview

Overview


Elephant ear (Elliptio crassidens), a mussel listed as Endangered in Wisconsin, is found in large rivers in the western part of the state. Only very old relic individuals have been found since 1920. The only known host is the skipjack herring, which only very rarely occurs in the upper Mississippi River and its tributaries.

State status

Status and Natural Heritage Inventory documented occurrences in Wisconsin

The table below provides information about the protected status - both state and federal - and the rank (S and G Ranks) for Elephant Ear (Elliptio crassidens). See the Working List Key for more information about abbreviations. Counties shaded blue have documented occurrences for this species in the Wisconsin Natural Heritage Inventory database. The map is provided as a general reference of where this species has been found to date and is not meant as a range map.

Documented locations of Elliptio crassidens in the Natural Heritage Inventory Database as of March 2012.

Summary Information
State StatusEND
Federal Status in Wisconsinnone
State RankS1
Global RankG5
Tracked by NHIY

Species guidance


Note: a species guidance document is not available at this time. Information below was compiled from publication PUB-ER-085-99 (now out-of-print).

Identification: The black to brown shell is moderately compressed and elongated. Anterior end is rounded and the posterior end is obliquely truncated and sharp. The ventral margin is almost straight and the beak is slightly elevated. The nacre color ranges from salmon to purple. Length to 6 inches (15.2 cm).

Habitat: The black to brown shell is moderately compressed and elongated. Anterior end is rounded and the posterior end is obliquely truncated and sharp. The ventral margin is almost straight and the beak is slightly elevated. The nacre color ranges from salmon to purple. Length to 6 inches (15.2 cm).

State Distribution: Occurs in the Mississippi River and the St.Croix River.

Phenology: The only known host fish is the skipjack herring (Alosa chrysochloris). Breeding season is from April through July.

Management Guidelines: The primary host fish for this species, the skipjack herring, has nearly been eliminated in the upper Mississippi due to locks and dams restricting migration from the Gulf of Mexico. Habitat destruction and river pollution have resulted in mussel declines. Protection of habitat and improvements in water quality along with restriction of dredging, impoundments, sand and gravel mining, and navigational improvements would benefit this species. The development of fish runways to facilitate the movement of host species through or around locks and dams would help to protect the elephant ear. Without a suitable host fish, extirpation is inevitable in Wisconsin and other upper Mississippi states.

Photos / Video

Photos


Elephant Ear  [Photo #13727]

Photo ©  Illinois Natural History Survey.


Last revised: Thursday, August 07, 2014