What is a horseshoe crab like? Why is it called the amazing species on the planet ?

It is a slow-moving sea creature whose blood color is blue. They have lived on the earth for hundreds of millions of years and are living fossils of the earth, so they are called "amazing species".

The horseshoe crab is what we often call a horseshoe crab. The reason why it is called a magical species on the planet is that I think it is also called a living fossil, and the strange color of blood and swimming habits are inextricably linked.

Crab-like, horseshoe crabs, close relatives of the long-extinct trilobites, have survived the Earth for more than four or a year, have survived five mass extinctions, and their blood cells are blue.

This guy is an ancient creature, its ancestors were born more than 400 million years ago, what is the concept, it is 200 million years earlier than the dinosaurs, and from 400 million years ago to today, the appearance has basically not changed, so the horseshoe crab also got the name of a living fossil. But now overfishing, coupled with environmental degradation, some of the stocks of horseshoe crabs, which originally had four populations, are now endangered.

The blood of horseshoe crabs is blue. Horseshoe crab has a unique medical value, the blood of horseshoe crab contains copper ions, and the color of copper oxidation is blue-green, so the extract of blue blood is "horseshoe crab reagent", which can accurately and quickly detect whether the internal tissues of the human body are diseased due to bacterial infection; In the pharmaceutical and food industries, it can be used to monitor toxin contamination. Scientists also use horseshoe crab blood to study cancer.

The horseshoe crab is a national second-class protected animal, it is an arthropod, the horseshoe crab resembles a crab, the body is blue-brown or dark brown, covered with a hard carapace, and has four eyes, two of which are compound eyes.

The ancestors of the horseshoe crab appeared in the Devonian period of the Paleozoic era in geological history, when the dinosaurs had not yet appeared, and the primitive fish had just appeared, and with the passage of time, the animals of its contemporaries either evolved or became extinct, and only the horseshoe crab still retained its primitive and ancient appearance from more than 400 million years ago, so the horseshoe crab is called a "living fossil".

The earliest fossils of horseshoe crabs were found in the Ordovician, and the fossils of horseshoe crabs similar in morphology to modern horseshoe crabs appeared in the Jurassic. Horseshoe crabs are as old as trilobites. Horseshoe crabs, also known as horseshoe crabs, are not crabs, but are related to scorpions, spiders, and extinct trilobites.

Invertebrates, the ancestors of shrimp and crabs.

Horseshoe crabs originated very early and are known as living fossils. The earliest horseshoe crab fossils were found in the Ordovician period (billions of years ago), and the horseshoe crab fossils with morphological similarities to modern horseshoe crabs appeared in the Jurassic period (billions of years ago). There are 3 extant genera:

Two genera are found along the coast of Asia and one genus is found off the coast of North America. The most well-known species is the only American horseshoe crab (Limulus polyphemus), which can reach more than 60 cm (2 ft) in length. 3 other kinds:

Three-spined horseshoe crab (Tachypleus tridentatus, Chinese horseshoe crab), giant horseshoe crab (T. tridentatus).Gigas) and Carcinoscorpinus rotundicauda, which are found in Asia, from Japan to India, and resemble the genus Limulus in morphology and habits. Horseshoe crabs are most abundant in the waters of the harbor, found in water at moderate depths in winter and on mudflats in the intertidal zone in summer.

Horseshoe crabs have always been used as food for humans and are natural enemies of soft-shell crabs. In the case of larval horseshoe crabs, the diet is dominated by monocytes, rotifers, larvae of abundant insects, and copepods. If it is an adult, it can eat shrimp and small fish.

The horseshoe crab is a marine arthropod that appeared in the ancient Devonian period and has not changed its form for 400 million years, so it is called a "living fossil". Horseshoe crabs are mainly found in the Beibu Gulf and the Gulf of Mexico in China, and are known as the "Chinese horseshoe crab" and the "American horseshoe crab", respectively. Due to the threat of marine environmental pollution, horseshoe crabs are disappearing off the coast of Japan and other countries.

But the real danger to this animal comes from the outlaws.

Shu Yuyan, director of the Biotoxin Committee of the Chinese Society of Toxicology, said: "Horseshoe crabs with blue blood have a unique role in medical research. If the reagent immediately coagulates or changes color, it means that the injection contains bacterial endotoxins that cause fever, shock and even death.

LAL can be widely used for endotoxin detection and quantification of injections, radiopharmaceuticals, vaccines and other biological products, various liquids, food and dairy products, etc.

In recent years, some criminals have taken a fancy to this unique role of horseshoe crabs, and they have wantonly purchased Chinese horseshoe crabs on the shores of the Beibu Gulf. They drained the horseshoe crab blood and finally brought it to restaurants where some diners devoured it. Fisherman Ah Hai said that in the past, there were countless horseshoe crabs on the local beaches, but now they are not easy to see due to excessive fishing and killing.

Fishermen have realized that it is illegal to hunt and kill Chinese horseshoe crabs, and they must consciously release them when they catch them at sea. According to reports, it takes 15 years for a horseshoe crab to reach adulthood, and medical workers pay great attention to protecting the ecological balance when collecting horseshoe crab blood, because a horseshoe crab can still survive if 1 3 or 2 3 of the blood is removed. "The phased development and utilization of coastal horseshoe crab resources can completely allow horseshoe crabs to donate blood in turns.

The nautilus appeared hundreds of millions of years ago.

The fisherman Ah Xiong catches the Chinese horseshoe crab, which looks like a turtle and is an ancient creature.