129
© Springer Nature Switzerland AG 2021
N. Gökoğlu, Shellfish Processing and Preservation,
https://doi.org/10.1007/978-3-030-60303-8_3
Chapter 3
Molluscan Shellfish
3.1 Bivalves
Bivalves are animals having two symmetrical shells belonging to the pelecypoda
class of molluscs and collected in the families of Mytilidae, Ostreide, Pectinidae,
Cardinidae, Donaeidae, Veneridae and Solenidae. They are found in marine and
freshwater environments. They have not an obvious head. The body is placed in two
shells joined by a hinge on the back. The shells are lined by a specialized tissue
called the mantle. In both shell, there is a shell-bound mantle which secretes the
shell, and a mantle cavity inside of the mantle which opens to the outer surface. Two
large lamellar gills are placed on the mantle cavity. Internal organs and foot are on
the abdominal side. The soft body inside of the shell includes a muscular foot, gills
(or ctenidia, used for respiration and feeding), muscles, a digestive system, nerves,
a three-chambered heart, and an open circulatory system (with sinuses). According
to the bivalve type, the foot has elastic fibrous (byssus) structure that can penetrate
and gouge the soft medium or adhere to the hard environment. Some species, such
as the hard-shelled clam have siphons. The abdominal siphon takes the water and
transmits it to the mantle cavity. The back siphon takes the water out of the mantle
cavity and throws it out (Atay 1997; Mikkelsen and Henne 2011).
Bivalves are an important part of marine biomass. Bivalves also account for a
large percentage of the total mollusc diversity in temperate regions. Marine bivalves
exploit a wide range of habitats, from intertidal rocks to subtidal sands and deep-sea
muds. Some bivalve groups burrow deeply into the sediments, and still others bore
into rock or wood. Both wild and cultivated bivalves have some functions in the
ecosystem. They play a role in water quality management. Due to their ability to
filter water, they purify water from particles and make water transparent. Thus, they
promote the production of phytoplankton by providing better penetration of light.
Direct ammonia excretion and mineralisation of bio-deposits, produced by the
bivalves, act as a source of inorganic nutrients. Through uptake and assimilation of
phytoplankton, the bivalves accumulate nutrients in their tissue, and harvesting of
© Springer Nature Switzerland AG 2021
N. Gökoğlu, Shellfish Processing and Preservation,
https://doi.org/10.1007/978-3-030-60303-8_3
Chapter 3
Molluscan Shellfish
3.1 Bivalves
Bivalves are animals having two symmetrical shells belonging to the pelecypoda
class of molluscs and collected in the families of Mytilidae, Ostreide, Pectinidae,
Cardinidae, Donaeidae, Veneridae and Solenidae. They are found in marine and
freshwater environments. They have not an obvious head. The body is placed in two
shells joined by a hinge on the back. The shells are lined by a specialized tissue
called the mantle. In both shell, there is a shell-bound mantle which secretes the
shell, and a mantle cavity inside of the mantle which opens to the outer surface. Two
large lamellar gills are placed on the mantle cavity. Internal organs and foot are on
the abdominal side. The soft body inside of the shell includes a muscular foot, gills
(or ctenidia, used for respiration and feeding), muscles, a digestive system, nerves,
a three-chambered heart, and an open circulatory system (with sinuses). According
to the bivalve type, the foot has elastic fibrous (byssus) structure that can penetrate
and gouge the soft medium or adhere to the hard environment. Some species, such
as the hard-shelled clam have siphons. The abdominal siphon takes the water and
transmits it to the mantle cavity. The back siphon takes the water out of the mantle
cavity and throws it out (Atay 1997; Mikkelsen and Henne 2011).
Bivalves are an important part of marine biomass. Bivalves also account for a
large percentage of the total mollusc diversity in temperate regions. Marine bivalves
exploit a wide range of habitats, from intertidal rocks to subtidal sands and deep-sea
muds. Some bivalve groups burrow deeply into the sediments, and still others bore
into rock or wood. Both wild and cultivated bivalves have some functions in the
ecosystem. They play a role in water quality management. Due to their ability to
filter water, they purify water from particles and make water transparent. Thus, they
promote the production of phytoplankton by providing better penetration of light.
Direct ammonia excretion and mineralisation of bio-deposits, produced by the
bivalves, act as a source of inorganic nutrients. Through uptake and assimilation of
phytoplankton, the bivalves accumulate nutrients in their tissue, and harvesting of