Oysters are vegetarians.
They eat algae -- microscopic plants that are rich in nutrients. The algae is filtered from the water by their gills. Mucous on the gills trap the algae. Special cilia on the gills move the trapped algae to the oyster’s mouth.

Oysters reproduce in summer.
Oyster larvae float in the water for about 10-18 days, then they settle to the bottom where they attach to a hard clean surface. After attaching they grow into oysters and never move again.

Newly attached oysters are called spat.
Spat are oysters less than 1 year old. Oyster spat require a hard clean surface on which to attach. While oyster shells are preferred for spat settlement, spat can attach to other types of shells and even rip rap, bulkheads, stones and other hard surfaces. Larvae that settle on mud or sand will die.

Oysters change sex.
Young oysters are mostly male. At 2 years old, most have changed to females. Older oysters are mostly females.

An oyster bar is a rich, diverse ecosystem.
Oysters provide habitat to many other creatures, making an oyster bar a living reef. Numerous attached organisms grow on the outside of oysters, such as mussels, barnacles, sponges, hydroids, amphipods, worms and bryozoans. These organisms attract fish and crabs.

Oysters grow about an inch a year; a 3-inch market oyster is about 3 years old.
They grow slower in lower salinity (about 1/2 an inch per year), and faster in higher salinity, sometimes reaching market size in 2 years.

A large oyster can filter up to 50 gallons of water per day during warm months.
The small oysters In a cage can filter over 100 gallons per day. A restoration site with 10 million large oysters can filter about 500 million gallons per day. However, today’s depressed oyster population has little, if any, affect on water quality because the population is so low relative to the vast size of the Chesapeake Bay.

The oyster population has been severely impacted by two diseases that kill oysters.
Although they are harmless to people who eat oysters, the diseases Dermo and MSX (microscopic protozoan parasites) have killed billions of oysters and degraded hundreds of oyster bars.

Oyster restoration efforts underway in Maryland include:
Creating hard habitat to enhance reproduction and increase the oyster population; stocking sites with hatchery produced oysters when natural reproduction is low; closing areas to harvest to protect stocks; and regulating the fishery to limit harvest.