CATDOLL : CATDOLL: Are swimming crabs from the sea or the river?

Are swimming crabs from the sea or the river?

The swimming crab is a very fat sea crab that comes from the sea, so there are no river swimming crabs on the market.

The head and chest of the swimming crab are covered with a prismatic cephalothorax, which is blue-grey in color, with a pair of well-developed chelipeds at the front and four pairs of walking legs at the back. They are distributed in the seas of northern and southern China. Generally, from south to north, the peak production season is from March to May and from September to October, and the production is higher in April and May in the Liaodong Peninsula of the Bohai Bay. A species of the genus Portunidae of the order Brachyura, also known as the crab, it is named because of its fusiform cephalothorax and three prominent warts on the back of the stomach and heart.

There are more than 50 species of the genus Portunus known in the Indo-West Pacific region, 17 species of which are found along the coast of China. This species is found in China, Japan and Korea. The front lateral margin is obliquely arched with 9 sharp teeth and a thorn at the end of the rear margin. The fourth (last) pair of walking legs are paddle-shaped and are used for swimming. The abdomen of the male is long and triangular, while that of the adult female is nearly round.

Sea crabs live in soft mud, sandy mud, rocks or water plants near the shore at a depth of 7 to 100 meters. A small number of smaller or medium individuals can also be collected at the low tide line of the intertidal zone.

Sea crabs often use the tips of the first three pairs of walking legs to crawl slowly on the seabed, swim with swimming legs, or move forward sideways or backwards. When encountering an enemy, they raise their large claws upwards to defend themselves or attack the enemy, or use the last two sections of their swimming legs to dig sand and dive into the seabed upright. They have the habit of foraging at night and have obvious phototropism, so they can be trapped with lights.

When swimming crabs live in the ocean, their survival rate is greatly reduced after leaving the high-salt and high-oxygen environment.

This is a sea crab. It cannot survive in the river, so naturally there is no swimming crab in the river.