ate crabs.

The word crab means crab.

Crab (páng xiè): Kingdom Animalia, phylum Arthropoda, subphylum Crustacea, class Mollusca, subclass Euphyla, decapoda, gastropodia, brachyurina. It is a crustacean (crustacean). Its body is protected by a hard shell and it breathes through gills. In terms of biological taxonomy, it is the same animal as shrimp, lobster, and hermit crab. Most types of crabs live in the sea or offshore areas, and some live in freshwater or land. They rely on female crabs to give birth to baby crabs, and each time the female crab lays a large number of eggs, the number can reach millions or more. Crabs rely on the geomagnetic field to determine direction. China has a long history of crab-eating, which is recorded in "Yi Zhou Shu Wang Hui Jie" and "Zhou Li Tian Guan Bu Ren".

The number of genetic materials of such organisms is complex and highly diverse, often as many as 100 pairs. Common crabs include hairy crabs (river crabs, hairy crabs, blue crabs), swimming crabs, etc. my country is rich in crab resources, among which the hairy crabs produced in the lower reaches of the Yangtze River include Gucheng Lake hairy crabs, Taihu Lake hairy crabs, Gaoyou Lake hairy crabs, Yangcheng Lake hairy crabs, and Crab House hairy crabs.

Although crabs are small, they have all five internal organs. After removing the hard shell of the crab, we can find that the crab's body is protected by a shell. These shield-like shells are called carapace by biologists.

The body of the crab is symmetrical and can be divided into the forehead area, eye area, heart area, liver area, stomach area, intestine area and gill area. The two sides of the crab's body are connected by appendages. The appendages on the head are called antennae, which provide touch and smell functions. Some appendages have mouth functions, which are used to tear food apart and bring it into the mouth.

The crab's chest has five pairs of appendages called thorax. The pair of appendages in the front are equipped with strong claws, which can be used for foraging. The remaining four pairs of appendages are the crab's feet. Crabs rely on these four pairs of appendages to walk and move. Their walking appearance is unique and unique. Interesting, most of them are walking sideways instead of going straight forward. The exception is monk crabs, which walk straight.

Crabs rely on the geomagnetic field to determine direction. Over the long time since the formation of the Earth, the magnetic north and south poles have reversed many times. The reversal of the geomagnetic poles disorients many organisms and even causes extinction. The crab is an ancient migratory animal. Its inner ear has small directional magnets and is very sensitive to geomagnetism. Due to the reversal of the geomagnetic field, the small magnets in the crab's body lose their original orientation. In order to survive the reversal of the geomagnetic field, crabs adopt the approach of "keeping the same constant in response to all changes". They simply do not move forward or backward, but walk sideways.

Crabs rely on the geomagnetic field to determine direction. Over the long time since the formation of the Earth, the magnetic north and south poles have reversed many times. The reversal of the geomagnetic poles disorients many organisms and even causes extinction. The crab is an ancient migratory animal. Its inner ear has small directional magnets and is very sensitive to geomagnetism. Due to the reversal of the geomagnetic field, the small magnets in the crab's body lose their original orientation. In order to survive the reversal of the geomagnetic field, crabs adopt the approach of "keeping the same constant in response to all changes". They simply do not move forward or backward, but walk sideways.

The head and thorax of a crab are indistinguishable in appearance, so they are called cephalothorax. The full legs of this animal grow on either side of its body. The first pair of chelicerae is not only a tool for digging holes, but also a weapon for defense and offense. The remaining four pairs are used for walking and are called walking legs. Each foot is made up of seven joints, and the joints can only move up and down. The width of the thorax of most crabs is greater than the length, so when crawling, they can only bend one side of the foot and grasp the ground with the toe, while the other side of the foot stretches outward. When the toe reaches the ground far away, it begins to contract. The originally bent foot immediately straightened, pushing the body to the opposite side. Since the lengths of these pairs of legs are different, the crab actually moves sideways and forward. However, not all crabs are allowed to run amok. For example, long-armed monk crabs that live in groups on the beach can run forward. Many spider crabs that live in seaweed can also climb vertically on the seaweed.

Through experiments, it was discovered that the bony eyes (where muscle bundles pass through) in the crab body are connected to the limbs. For each limb, there are two upper and lower bony eyes (i.e. two bundles of muscles) connected to it. Moreover, the bending direction of the joints at the base of its limbs is in the dorsal and ventral direction, so when the muscles contract, it affects the limbs to move in the dorsal and ventral direction, so the crab moves laterally.

The vowel letter a is pronounced as a short vowel /?/ in a stressed closed syllable. When pronouncing it, the tip of the tongue is close to the lower teeth, the front of the tongue is raised, and the tongue position is low. It is the four front Among the vowels, it has the lowest tongue position but the largest opening. It is a short vowel. However, it is quite long in actual pronunciation. The gums are between half-open and open, and the lips are not rounded. This sound appears at the beginning and middle of words, such as:

mat mat

map map

bag bag, bag

cat cat

hat wide-brimmed hat

fan fan

bat racket, bat

apple apple

hope I can help you clear up your doubts.