**2.5** *Astacus leptodactylus*

Although the Eastern European crayfish (*Astacus leptodactylus*) was considered an important commercial product (a luxury food item) in the world after the 1830s, it was only used in World War II in Turkey. After the World War II, it became one of the important export products among aquaculture products. While the total crayfish production was 500 tons in 1979, this value was 6500 tons in 1982, and after 1986, it gradually decreased due to the occurrence of crayfish plague (*Aphanomyces astaci*), overfishing and environmental pollution. Today, total crayfish production (1894 tons, 2002 data) is around 15% of the 1980s. About 600 crayfish species are found naturally in other continents except Africa and Antarctica. In addition, crayfish migrate from their original environment to other environments, intensively, naturally (with migration or currents); They were transported by chance (by ships' ballast waters, channels, being used in traps for catching fish, escaping from the environments where they were kept under control, being carried by predators or people unknowingly) or consciously by people (keeping them as a hobby in aquariums, production and aquaculture, control of aquatic plants). The most important and common factor in the transportation of crayfish from one environment to another is the desire of entrepreneurs to earn economic income from these creatures (**Figure 7**) [23].

The trunk is divided into two parts, the thorax, and the abdomen. The chest is covered with a hard and prominent shell. The skeleton-shell is outside. The shell is immobile and hard except for the articular parts. The joints are soft and thin, and their structure is also different. There are 4 pairs (8 pieces) of feet for walking in the chest part. The abdomen consists of 6 segments. Freshwater crayfish are smaller

**Figure 7.** Astacus leptodactylus, *Eschscholtz, 1823 [13].*

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

and red in color. Those that live in salt water are also larger and lighter in color. They are voracious and aggressive species. It is found in rivers, lakes, streams, and ponds. In many countries, the consumption of crayfish with pleasure and the increase in its economic value day by day has accelerated the production of this product under cultural conditions. It is cultivated on farms in Europe, especially in South America. There are 300 different types available. Some species are distinguished by the red or white color of their claws. Their shells are red, brown, and purple in color. It has lean and delicious pink, white flesh. Crayfish normally have a heavy, wobbly gait. Walking is forward through the legs. However, their swimming is backwards. Crayfish generally like flowing and abundant calcareous waters. It enables the development of limestone crusts. They are rarely found in acidic waters. It can be sold live, cooked, frozen, or canned. If cooked, those with firm skins and complete claws should be chosen. It must be cleaned before cooking. It contains very little meat. Live crayfish can be stored wrapped in a damp cloth for 12 hours in the refrigerator, 1–2 days in the refrigerator when cooked, and 1–2 months frozen [24].
