Crested oyster

Ostrea equestris

Family Ostreidae - oysters

Bivalve (2 shells); shell oval to triangular; color usually brownish green (from algae, mud and other encrusting organisms, typically white when all removed); interior pearly with gray to greenish tinge; surface sculpture variable; top shell usually flat; bottom (attached) shell usually deep with elevated margins; margins may be smooth or fluted, sometimes with zig zag shape when viewed laterally; muscle scar on inside shell colorless; margins on inside of shell with numerous small parallel ridges or indentations.
Similar Species
Difficult to distinguish from the eastern oyster without opening the shells. Sometimes a fluted or zig zag lateral margin helps distinguish the two. Inside the shell, the crested oyster has the small lateral ridges that are absent in the eastern oyster, and its muscle scars are colorless (purple in the eastern oyster). The crested oyster only grows to a max of 5 cm (2 in) and prefers saltier water than the much larger eastern oyster.
Bay, in high salinity areas
Maximum Size
5 cm (2 in)
Other Common Names
horse oyster
Previous Scientific Names