Oysters

Anatomy

Lifecycle

Why the Decline

Disease

Comeback

Oysters in months without an R

 The  life cycle of the Eastern Oyster                      Crassostrea virginica

In general, oysters reproduce in the wild similar the Northern Quahog (hard calm)

Introduction

The Eastern oyster can grow up to 10 inches in length and can live to approximately 20 years of age.

Oysters begin their adult lives as males.  At any one time, an oyster is either male or female.

Sperm cells are much smaller than eggs and require less metabolic energy to produce. 

Reproduction

Spawning   

When conditions are right, male oysters release sperm and females release unfertilized eggs  into the bay.  Fertilization takes place in the water column as sperm and egg unite. 

  As the fertilized egg develops the cells divide and the  embryo grows.

 With further development we see the growth of hair-like cilia and the embryo becomes a free-swimming larva known as a trocophore. 

Next, the larva begins to develop a shell and foot. In this stage, the larva is called a veliger.

The larval shell of the of the umbonate veliger has the characteristic shape of the oyster.

 The last phase of the veliger stage is called the The pediveliger (ped = foot) stage.  This is the final stage prior to settlement and eventual metamorphosis to juveniles.

 Pediveligers have a well-developed foot that extends from the shell.

 Pediveligers settle to the bottom and can crawl short distances to find suitable sites for
setting.

Setting occurs when the larva cements itself to a hard substrate (usually oyster shells) and
metamorphoses into a tiny oyster called a spat.

“Spat” usually refers to a recently metamorphosed oyster, but the term may be applied to any small oyster.

Similarly, the term “seed oyster” may be given to oysters that are too small to harvest, but
it generally refers to juvenile oysters larger than spat.

Fun Fact - Oysters are active and grows in water temperature above 40° Fahrenheit.  Below this temperature they shut down (hibernate).