Crabs, short-tailed crayfish (Brachyura), suborder invertebrates
animals of the order decapod crustaceans.
The head is small; eyes are stalked. The chest is wide,
the width of the chest shield is from 2 to 20 cm, in the Japanese deep-sea
crab (Macrocheira kaempferi) up to 60 cm.The first pair
walking legs are equipped with claws.
The abdomen is short, bent under the cephalothorax; abdominal
limbs in males (2 pairs) converted to copulative
apparatus, in females (4 pairs) are used for bearing eggs.
They live in the seas, in fresh water bodies and on land. Everything
crabs, except for freshwater ones, breed in the sea. Development
crab occurs with metamorphosis; comes out of the eggs
zoea larva, which turns into a megalopa larva,
and then into an adult crab. Only in freshwater crabs
(family Potamidae) no free-swimming larva.
The pursued crab is capable of breaking off with a sharp movement
limbs, in place of which new ones grow.
Crabs feed mainly on invertebrates.
Many crabs are edible and fished. T.
n. Kamchatka crab is close not to crabs, but to hermit crabs.
Some crabs destroy commercial molluscs – oysters and mussels,
and the Chinese fur-handed crab (Eriocheir sinensis) sometimes,
entering rivers, destroys dams in which he arranges
burrows and also spoils fishing nets.
More than 4 thousand species of crabs are known,. about 50 types.
Crab meat has a low calorie content, since 100
g of such meat contains 73 kcal. Boiled crabs contain 96
kcal per 100 g, and the energy value of canned crabs
– 85 kcal per 100 g. In 100 g of cooked crabs
for a couple, contains 97 kcal. Crab meat has a lot of
proteins and the body is well saturated with energy. In moderation
this product does not cause obesity.
Nutritional value per 100 grams:
Proteins, g Fats, g Carbohydrates, g Ash, g Water, g Calorie content, kcal 18,3 0,6 – 1,8 79,6 73
Useful properties of crabs
Crab meat is a physiologically valuable product
nutrition. It is usually consumed boiled. It
appreciated for its high taste and for what it contains
biologically active substances. Raw crab meat
has a jelly-like consistency and a grayish color.
Crab meat contains 80,1-82,5% moisture, 0,2-1,4%
lipids, 11,6-19,2% protein, 1,2-2,2% ash. Crab meat
contains more essential amino acids than fish meat.
It also contains a large amount of glycogen.
(in Kamchatka crab – up to 2,4%). This carbohydrate gives
crab meat has a pleasant sweetish taste. In crab meat
contains B vitamins. Compared to other foods
vegetable and animal origin, crab meat
favorably with a high level of biologically active magnesium,
Of the trace elements, a high copper content is found in it.
For this reason, crab meat has such a vice,
like blue discoloration – formation of colored copper compounds
under the action of enzymes.
Edible meat is located in the limbs and abdomen.
The limbs are made of carapace tubes connected
joints. A bundle of muscle fibers that form the musculature
limbs, rests on chitinous plates connected
with a shell in the area of the joints. Under the shell the body of the crab
covered with a red film, which is the basis for education
new shell after the molt of the crab, if it remained
in the sea.
Crabs are not only dietary, but also rich in vitamins, amino acids
and trace elements. This is iodine,
and calcium, zinc,
polyunsaturated fatty acids, antioxidants: taurine
and vitamins E and C.
Crabs are also useful for anemia, cardiovascular
diseases and deterioration of vision.
A number of high quality products can be produced from crabs:
make canned food, boiled-frozen crab legs,
dried meat. Sale of fresh and chilled crabs
must be done very quickly: at a temperature not
above 12-15 ° C crabs are stored for no more than 15 hours, and sprinkled
finely crushed ice – 30-36 hours.
Record holders for sodium
Dangerous properties of crabs
Eat crab meat carefully, as it can
be contaminated with bacteria due to the peculiar nutrition of these marine
inhabitants. And regular over-consumption of contaminated crabs
can lead to severe toxic poisoning, and can also
provoke loss of hearing, vision, disruption of the nervous system.
Also, crab meat is contraindicated for people with allergies.