Shellfish IQ

Shellfish: a healthful addition to a balanced, low-fat diet. Beef and pork can contain over 40 percent of the calories from fat. Shellfish, such as clams and scallops, contain 15 percent or fewer calories from fat. Even oyster, mussel, and geoduck meats only contain approximately 20 percent to 28 percent calories from fat.

Shellfish: A Source of the ‘Good' Fats

Salmon and other fatty fish are rich sources of the ‘good' fats called omega-3 fatty acids. Shellfish also contain significant amounts of these fats. If the shellfish is cooked until done, but not overcooked, then omega-3 fatty acids are usually preserved.

Shellfish are called Filter Feeders

Shellfish are referred to as filter feeders because they feed by drawing water through their gills and filtering out tiny plants and animals called plankton. A large oyster can filter up to seven gallons of plankton-bearing water an hour; a clam, half that amount.

What's in a Name: Mollusks or Bivalves?

Oysters, clams and mussels are classified as mollusks and are relatives of other spineless animals such as snails and octopuses. They are further classified as bivalves because they have two-part shells held together by a ligament hinge.

Shellfish Keep the Water Clean

In the ecosystem, bivalve shellfish filter seawater and in the process help regulate vital flows of nutrients and energy in the overall coastal system.

Do Oysters Breath?

Yes, oysters breathe much like fish, using both gills and mantle. The mantle is lined with many small, thin-walled blood vessels which extract oxygen from the water and expel carbon dioxide. A small, three chambered heart, lying under the abductor muscle, pumps colorless blood, with its supply or oxygen, to all parts of the body. At the same time a pair of kidneys located on the underside of the muscle purify the blood of any waste products it has collected.

How do oysters produce pearls?

Pearls begin when a foreign substance, such as a grain of sand, lodges in the shell. The oyster's body reacts by depositing layers of nacreous (pearl-like) material around the foreign body to wall it off and reduce irritation.

Are Oysters Male or Female?

There is no way of telling male oysters from females by examining their shells. While oysters have separate sexes, they may change sex one or more times during their life span. The gonads, organs responsible for producing both eggs and sperm, surround the digestive organs and are made up of sex cells, branching tubules and connective tissue.

Why do clams squirt water through their siphons? What purpose does the siphon serve?

The siphon of a clam serves three main purposes: breathing, obtaining food, and eliminating waste products. Since clams are relatively immobile and movement is usually limited to burrowing in the sand, their siphon - which operates much like a snorkel - is their lifeline. Inflowing water is pumped through the siphon, passed over the gills, and strained to remove food particles. After receiving carbon dioxide from the gills and other waste products from the digestive tract, the water is expelled through the outgoing siphon.

Did You Know that….

Bivalve filter feeding shellfish can be regarded as the canaries of coastal health, providing an early warning system of environmental degradation.