**2.1** *Mytilus galloprovincialis*

The black mussel, whose scientific name is *Mytilus galloprovincialis* (Lamarck, 1819), is also known as the Mediterranean Mussel. The Black mussel is in the Bivalvia (bivalves) class of the Mollusca (**Figure 3**).

Mussels are creatures consisting of bivalves, interlocked with each other with a very strong musculature, triangular in front, ovoid in the back and bilateral

**Figure 1.** Rapana thomasiana*, Gross 1861 [6].*

*The Effects of Shellfish Consumption Frequency for Human Health DOI: http://dx.doi.org/10.5772/intechopen.100405*

**Figure 2.** Octopus vulgaris*, Linnaeus 1758 [7].*

**Figure 3.** Mytilus galloprovincialis, *Lamarck, 1819 [8].*

symmetry. The shell consists of anterior margin, posterior margin, ventral margin, and dorsal margin. The leading margin is very brief and the shells interlock here. The outside of the shell is in diverse trace of purple-black and brown, and the inside is of pearl shine. There are growth lines on the shells that draw small elliptical circles starting from the junction of the shells. Although the common height of this species is 5–8 cm, it can reach a maximum of 10–11 cm. The temperature and salinity of the region have an important effect on the development of mussels, and the most delicious period of mussel meat is from autumn to the beginning of spring. Since bivalve mollusks feed by filtering water, they accumulate microbiological, chemical, or natural toxins in polluted aquatic environments, therefore, they must be given for consumption in a controlled manner. In aquatic environments with increased pollution, aquaculture rather than hunting is the most reliable way to enable controlled production [14–16].

Black mussel is a popular seafood that is consumed with admiration all over the world, especially in European and Pacific countries. These creatures, which live in the coastal regions of the marine ecosystem, can be obtained from nature by hunting or they can be produced through culture. Mussels, which have as valuable and quality protein as fish meat, can be consumed in various ways such as stuffed mussels, pan and brine. Mussels, which have a short shelf life, should be prepared, and consumed as soon as possible or stored by paying attention to storage conditions [16].

#### **2.2** *Penaeus keathurus*

Shrimp are ten-legged arthropods that live in fresh and salt water. Freshwater shrimps are mostly common in tropical regions. Their size is varying cylindrical body between 1 and 30 cm. Its body is covered with an armor made of calcium carbonate. These creatures, whose bodies are jointed, swim backwards by waving their wide, fin-like tails. It has five pairs of legs and at least two of them have claws. The antennae, which are two pairs, are very long and bifurcated. At least one of these forks bends back, allowing the shrimp to retract into the crevices and signal danger from behind. The most obvious reaction of the shrimp in the face of danger is to try to protect itself with a sudden twist. Their body color can change to suit their environment. There are large-clawed predators that feed on small fish, as well as scavengers that feed on food particles in the sand. In some species, there are brush-like bristles on their claws to easily collect food particles (**Figure 4**) [17].

Some types are less tasty than others and some types are not consumed. It is farmed in countries such as America, Japan, Thailand, and Taiwan. Consumption in the USA is higher than in other countries. Since shrimp species found in cold waters grow slowly, their meat is more delicious. Depending on the species, their flesh can be firm and transparent, pink, yellow, gray, brown and red. The flesh color, which is transparent when cooked, takes a dull and pinkish color. One of the commercially important species is the deep-water shrimp (*Pandalus borealis*). The other is the large black shrimp (*Penaeus monodon*). Since shrimp species spoil easily after hunting and melanosis (black spots) form on their meat, they should be cooled immediately, and their heads should be cut off. The most expensive of the shrimp species are the largest ones. If fresh shrimp are to be bought, their bodies should be firm, not sticky, and soft, their bodies should not be separated from their shells and their heads should not be surrounded by black spots. It can be stored fresh for about 2 days in the refrigerator and frozen for 1 month [18].

#### **2.3** *Loligo vulgaris*

Squid, like other cephalopods, has a prominent head, bilaterally symmetrical structure, mantle, and arms. The substance called melanin in it is the same pigment that tans human skin. Its eyes are in the middle of its head and body. It has 8 arms surrounding the mouth with a sharp, parrot-like beak, and two distinctly longer tentacles. Most of the squid is formed by a thick muscle cover called the mantle, which protects the internal organs and allows the squid to move through the water by spraying strongly with water. It compresses the water in the mantle and sprays the water quickly from the section also called siphon, allowing it to swim backwards. Thanks to its funnel-shaped structure that creates a jet effect, squid can accelerate in water more than 3 times the speed of Olympic swimmers (**Figure 5**) [19].

**Figure 4.** Venus verrucosa, *Linnaeus, 1758 [9].*

*The Effects of Shellfish Consumption Frequency for Human Health DOI: http://dx.doi.org/10.5772/intechopen.100405*

#### **Figure 5.** Penaeus keathurus, *Forskål, 1775 [10].*

Squid, which is the lowest calorie seafood product, contains protein, very little fat, phosphorus, magnesium, and calcium. It also contains vitamins B2, B3 and B12. To clean the squid, the internal organs must be removed by pulling from the tail. By holding the tip of the squid, it is necessary to quickly pull and clean the outer skin. After cleaning the outer skin and internal organs, the transparent bone in the middle of the squid should also be removed and the squid should be washed well. The cleaned squid is offered for sale in the form of rings and frozen. Fresh squid can be stored in the refrigerator for 1–2 days. Frozen squid can be stored in the freezer for 1–2 months [20].
