Chinese horseshoe crab (scientific name: Tachypleus tridentatus): The body length can reach 60 cm and the weight is 3-5 kg. The horseshoe crab consists of three parts: the head and breastplate are slightly horseshoe-shaped (hence the name horseshoe crab), the abdomen is hexagonal with spines on both sides, and the tail is a long tail sword. Limulus is like a crab, bigger than it. Although they all have joint appendages, the relationship between horseshoe crab and horseshoe crab is far less close than that with spiders.

The first pair of appendages of horseshoe crab and spider are chelated. All have four pairs of feet, which are taxonomically called chelated animals. The main difference between horseshoe crab and spider is that horseshoe crab has many spines at the base of its appendages and surrounds its mouth to chew food, so it is also called arthropod.

Living on the sandy bottom of shallow sea. Mainly carnivorous animals, feeding on annelids and mollusks, and sometimes feeding on benthic algae. The growth cycle of Chinese horseshoe crab is very long, and it takes nearly 13 years to complete reproduction. The blood of horseshoe crab is blue because it contains copper ions. The blood of Chinese horseshoe crab is blue.

food

Limulus is mainly carnivorous animals, feeding on annelids and mollusks, and sometimes feeding on benthic algae. When eating, the food is sent to the mouth with the pincers, rubbed and chewed with the base of the jaw, and then sent to the mouth. Behind the mouth is the esophagus, which expands forward into a gizzard, in which horny teeth can grind food and enter the midgut after passing through the valve.

Its front end is the stomach, and there are 1-2 pairs of developed hepatic diverticulum, whose branches reach the head, chest and abdomen, and there are hepatic ducts opening to both sides of the stomach.

digest

Hepatic diverticulum is a place for chemical digestion and absorption of food. Behind the midgut is the rectum, with the anus opening at the end of the abdomen and the ventral surface before the tail sword. The circulation system is open. There is a tubular heart on the back of the digestive tract, located in the pericardiac sinus, with 8 pairs of heart holes and developed blood vessels. There are 3 anterior arteries forward and 4 pairs of lateral arteries on both sides. After the arterial branches enter the tissue, two large abdominal blood sinuses are formed on the ventral surface. Blood flows from the abdominal sinus into the gill of the book, and then flows back to the heart through the pericardial sinus and cardiac orifice after gas exchange.

Blood contains hemoglobin and a kind of deformed cells, which have strong coagulation function. The excretory organs are four pairs of basal ganglia, which are located on both sides of the grinding stomach. The metabolic wastes collected by the glands are sent into a same bag, and then open at the base of the last pair of feet through the drainage tube, bladder and drainage hole. The basal ganglia also have the function of water regulation.