Scallops

For another understanding, see shells (disambiguation)

Anadara granosa blood clad
Shellfish are aquatic animals including soft-bodied animals (molluscs).

Molluscs are beneficial
Coque blanche (Cerastoderma edule) .jpg
Seafood products ("seafood")
Abalon
Mussels
Scallops
Periwinkel
Kupang
Oyster
Simping
Squid
Octopus
Cuttlefish
Fishing industry
Aquaculture
This box:
see edit talk
The definition of shellfish is general and has no biological significance but its use is wide and is used in economic activities.

In the broadest sense, shellfish means all molluscs with a pair of shells (see Bivalves). With this understanding, it is more appropriate to call it shellfish and commensurate with the meaning of clam used in America. Examples of such usage can be seen in the term "craft from shells".
The word shell can also mean all the shells whose life is attached to an object. These include edible species, such as shellfish and green shell (kupang awung), but do not include edible species but lying on sand or aquatic base, such as lokan and mussels.
Shellfish are also used to refer to a variety of shell-shelled thick, calcareous, with a radial pattern on a firm shell. In this sense, green shells are not included and more properly called kupang. The closest understanding in English is cockle.
In the most narrow sense, what is referred to as mussels are blood clams (Anadara granosa), a type of common cultivation shells found in the Indo-Pacific region and sold in many stalls or restaurants selling seafood.
General Characteristics Edit

All shells have a pair of shells (also called grafts or valves) which are usually symmetry of a mirror connected to a ligament (connective tissue). In most shells there are two adductor muscles that regulate the open-lid of the shell.

Shells have no head (also brains) and only the eyebrows have eyes. The organs are kidney, heart, mouth, and anus. Shellfish can move with "feet" in the form of a flattened organ expelled from the shell at any time or by opening the lid of the shell in a shock.

The circulation system is open, meaning it has no blood vessels. The supply of oxygen comes from the very liquid blood that is rich in nutrients and oxygen that surrounds its organs.

Food shells are plankton, by means of filtering. The shell itself is a prey for squid and sharks.

All shells are male when young. Some will become females along with maturity. [Need a reference]

Shells have gonads, genital glands that produce sperm or eggs depending on the sex of the shell. [Need a reference] Egg fertilization occurs externally where sperm and eggs meet in water. The fertilized egg develops into a larva called a trochophore, which will swim with the current and stick it somewhere before it begins to form a shell.