Archerd Shell Collection > Shell Classes > Bivalvia > Ostreidae

Family: Ostreidae (Oysters)

The Ostreidae, or true oysters, are the food oysters of commerce world-wide. While all oysters are capable of secreting the nacre that forms pearls, those of the Ostreidae family are inconsequential (gemstone pearls are commercially harvested from oysters of the more distantly related Pteriidae family).
Despite obvious shell differences, oysters and scallops (Pectinidae) are related in that both molluscs have a central adductor muscle with the characteristic central shell scar. In the Ostreidae, the central adductor muscle is  much larger and not bounded by ridges. Radial ribbing if present subdivides and is more irregular, as is also the shell shape, which beomes distorted by cementation to other objects. If present, denticles or teeth along the shell margin are characteristic of individual species. The remarkable Cock's Comb oyster is typically heavily encrusted by sponges, as shown in the live photos, at right below.
Reproductive behavior in the oyster is remarkable in that both oviparous (egg   bearing) and larviparous (larvae bearing) species are found. The larviparous species, of which Ostreia edulis is typical, show a life history of alternating sex changes in the same individual, whereas the oviparous species, e.g., O. virginica, or O. gigas, are essentially hermaphroditic and may produce either predominantly male or predominantly female gametes depending on environmental temperature and nutrient availability (Morton, 1960).
Class: Bivalvia
Subclass: Pteriomorphia
Order: Ostreina
Superfamily: Ostreacea
Family: Ostreidae
Major Genera
  • Genus: Crassostrea
  • Genus: Hyotissa
  • Genus: Lopha
  • Genus: Ostrea
  • Genus: Saccostrea
Lopha_crystagalli.JPG (40613 bytes)
Lopha cristagalli (Linnaeus, 1758)
Cock's Comb Oyster

Oestraea_edulis.JPG (48462 bytes)
Ostrea edulis (Linnaeus, 1758)
Common European Oyster


Doug Segar and Elaine Stamman Segar,

Lopha cristagalli
from Milne Bay, Papua, New Guinea


Creative Commons License
(Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Generic License)

Lopha cristagalli
from Turtle Cave, Sabah, Malaysia

Archerd Shell Collection > Shell Classes > Bivalves > True Oysters