Fish and shellfish are commonly known as Seafood. There are different types of Seafood occurred in this world, based upon their nature the classification of Seafood are below.
Vertebrates have skin and scales which cover the body. They move with the help of their fins.
They are subdivided into :
Flat (White or Lean) Fish
These are mainly flat fish and contain oil only in the liver.
Most of these are deep sea fish. E.g. Sole, Plaice, Lemon Sole, Skate, Flounder, Turbot, Dab, Halibut, Brill etc.
A real flat fish will have both the eyes on the same side. Common local examples are Sole.
Oily (Round) Fish)
These are mainly round fish and contain fat all over the body. The amount of fat varies from 0.5 to 20% in different varieties.
These fish are often pigmented and tend to be surface fish. Fresh Water fish include Trout, Crap, Pike, Eel, Salmon etc.
In this classification of Seafood include Red mullet, Sea Bass, Red Snapper, Gray Mullet, Red Bream, Cod, Hake, Whiting, Sardine, Whitebait, Sprat, Mackerel, Herring, Smelt, Pollack, Monkfish, and Haddock etc.
Want more information about fishes read the post Cuts of Fish
Cephalopods mean shellfish that have legs over their heads.
They are closely related to snails family but the only difference is that they do not have external shells like the snails, instead they have internal shells that are made from a spongy material.
Or in another definition say that
These types of fish or seafood have neither bones nor shell. Some of them have small cartilage e.g. Squid, Octopus, Cuttle fish etc.
Shell fish may be divided into:
Molluscs are the shellfish that have a hard inedible shell. They are divided in to following group
Molluscs may be further divided into :
These are recognized by the characteristic spiral formation of their shells, which unlike those of bivalves, are not divided into halves e.g. Whelks, Winkles etc.
These have two distinctly separated shells joined by a hinge-like membrane. The movements of shell are controlled by a strong muscle.
When the muscles relax, the two halves of the shell fall open.
The shell also opens when the organism dies, thus exposing the contents of the shell to contamination from outside, e.g. Oysters, Scallops, Mussels, Clams and Cockles.
The shells of the Molluscs increase at the rate of one ring per year to allow for the growth of the organism.
The age of the molluscs can thus be roughly estimated by the number of the rings on the shell.
These have a segmented crust like shell e.g. Lobster, Crabs, Prawns, Shrimps, Crayfish (has claws), Crawfish (has no claws).
The shells of the crustaceans don’t grow with the fish, unlike those of the Molluscs, but are shed each year, with a new one forming to suit their new size.
Basically these are classification of Seafood done by their nature of Fish and shellfish, if you are any query about you can comment below.