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move en masse from one area to another. In scallops, the shell shape tends to be
highly regular, and is commonly used as an archetypal form of a seashell
(Wikipedia 2019i).
Scallops have many small eyes arranged along the edge of their mantles. These
eyes represent an innovation among molluscs, relying on a concave, parabolic mirror of guanine crystals to focus and retro-reflect light instead of a lens as found in
many other eye types (Wikipedia 2019i).
Scallops are filter feeders and eat plankton. Unlike many other bivalves, they
lack siphons. Water moves over a filtering structure, where food particles become
trapped in mucus (Wikipedia 2019i).
In the Pectinidae, gametes are released into the sea and fertilisation occurs externally. Sperm penetration takes place while the egg is at the metaphase I stage of
meiosis (Cragg 2006). Spermatozoa and ova are released freely into the water during mating season, and fertilized ova sink to the bottom. After several weeks, the
immature scallops hatch and the larvae, miniature transparent versions of the adults
called “spat”, drift in the plankton until settling to the bottom again (an event called
spatfall) to grow, usually attaching by means of byssal threads (Wikipedia 2019i).
Distribution of Scallops
There are some 400 known living species in the bivalve family Pectinidae, commonly known as scallops. They occur in all the seas of the world from polar regions
to the tropics. Most of the commercially important species occur in the inshore
waters of the continental shelves but scallops are found in waters of all depths from
the intertidal zone down to some 7000 m (Brand 2006).
Scallops inhabit all the oceans of the world, with the largest number of species
living in the Indo-Pacific region. Most species live in relatively shallow waters from
the low tide line to 100 m, while others prefer much deeper water. Although some
species only live in very narrow environments, most are opportunistic and can live
under a wide variety of conditions. Scallops can be found living within, upon, or
under rocks, coral, rubble, sea grass, kelp, sand, or mud. Most scallops begin their
lives as byssally attached juveniles, ability that some retain throughout their lives
while others grow into free living adults (Wikipedia 2019i).
Fishing/Harvesting of Scallops
Bottom-cultured scallops are harvested either by hand (SCUBA divers) or dredge.
Scallops cultured in suspension are harvested by different means. For example, the
harvest of P. yessoensis from suspension culture employs the use of vessels outfitted
with winches to lift longlines and associated nets (Heinonen 2013). For wild scallops, dredge harvest techniques are used. Dredges are steel-framed structures with
or without a cutting bar on the leading edge that drags above the surface of the
3 Molluscan Shellfish
move en masse from one area to another. In scallops, the shell shape tends to be
highly regular, and is commonly used as an archetypal form of a seashell
(Wikipedia 2019i).
Scallops have many small eyes arranged along the edge of their mantles. These
eyes represent an innovation among molluscs, relying on a concave, parabolic mirror of guanine crystals to focus and retro-reflect light instead of a lens as found in
many other eye types (Wikipedia 2019i).
Scallops are filter feeders and eat plankton. Unlike many other bivalves, they
lack siphons. Water moves over a filtering structure, where food particles become
trapped in mucus (Wikipedia 2019i).
In the Pectinidae, gametes are released into the sea and fertilisation occurs externally. Sperm penetration takes place while the egg is at the metaphase I stage of
meiosis (Cragg 2006). Spermatozoa and ova are released freely into the water during mating season, and fertilized ova sink to the bottom. After several weeks, the
immature scallops hatch and the larvae, miniature transparent versions of the adults
called “spat”, drift in the plankton until settling to the bottom again (an event called
spatfall) to grow, usually attaching by means of byssal threads (Wikipedia 2019i).
Distribution of Scallops
There are some 400 known living species in the bivalve family Pectinidae, commonly known as scallops. They occur in all the seas of the world from polar regions
to the tropics. Most of the commercially important species occur in the inshore
waters of the continental shelves but scallops are found in waters of all depths from
the intertidal zone down to some 7000 m (Brand 2006).
Scallops inhabit all the oceans of the world, with the largest number of species
living in the Indo-Pacific region. Most species live in relatively shallow waters from
the low tide line to 100 m, while others prefer much deeper water. Although some
species only live in very narrow environments, most are opportunistic and can live
under a wide variety of conditions. Scallops can be found living within, upon, or
under rocks, coral, rubble, sea grass, kelp, sand, or mud. Most scallops begin their
lives as byssally attached juveniles, ability that some retain throughout their lives
while others grow into free living adults (Wikipedia 2019i).
Fishing/Harvesting of Scallops
Bottom-cultured scallops are harvested either by hand (SCUBA divers) or dredge.
Scallops cultured in suspension are harvested by different means. For example, the
harvest of P. yessoensis from suspension culture employs the use of vessels outfitted
with winches to lift longlines and associated nets (Heinonen 2013). For wild scallops, dredge harvest techniques are used. Dredges are steel-framed structures with
or without a cutting bar on the leading edge that drags above the surface of the
3 Molluscan Shellfish