What is horseshoe crab (hòu)? Many people subconsciously understand him as a turtle when they see this word. In fact, this is understandable, because it does look like a turtle.
The horseshoe crab's body is divided into three parts, with a broad head and thorax in front. The head has two large eyes , flanked by a pair of compound eyes, followed by a segmented abdomen and a long tail. Think of it as a living bike mat, but with a small tail behind the mat.
Don't look at its appearance, it is a living fossil that has lived for 400 million years. From 400 million years to the present day, they have witnessed the birth of fish, the extinction of dinosaurs, and the rise of humans. However, they themselves have not changed, and their basic form and cellular form are still similar to before.
And their blood was different from most animals today.
The blood of ordinary animals is mostly red. This is mainly because the blood of most animals contains hemoglobin, which is mainly a protein that transports iron. When iron reacts with oxygen in the blood, it appears red.
The blood of horseshoe crabs is very different from other animals, horseshoe crab blood has no iron but contains a lot of copper, copper combined with oxygen in the blood to form blue. There are some other animals in nature that also have blue blood, such as octopuses, shrimp and crabs, all of which have blue blood.
The attention of horseshoe crabs began in the 70s of the 20th century. Scientists have found that the blue blood of horseshoe crabs is very different from other animals. The blood of horseshoe crabs contains amoebic cells, which will coagulate when they encounter bacteria, and the coagulated amoebic cells will wrap the bacteria and trap the cells alive.
This property of horseshoe crabs gives it a natural advantage when it comes to facing bacteria. But you can't eat it all over the world, if large-scale bacteria enter the horseshoe crab's body, then the horseshoe crab will also drink and hate on the spot. Because there are too many bacteria, the amoebic cells in the horseshoe crab's blood will continue to coagulate, eventually leading to blood blockage and ischemic death.
According to this property, as long as horseshoe crab blood is used as a raw material to make a reagent, it is easy to detect whether the sample contains bacteria. This makes him a sweet potato in the medical community, for example, vaccines need to be tested for LAL reagents before they are marketed, and only vaccines that pass the test can be marketed. In addition, horseshoe crab blood is also widely used in the field of food safety.
For people, this is a great thing, but for horseshoe crabs, it is the beginning of a nightmare.
From the moment the detection characteristics of horseshoe crabs were discovered, large-scale hunting of horseshoe crabs began to draw blood. Due to uncontrolled fishing, horseshoe crab populations are declining. People grabbed and tied the horseshoe crab to a machine, inserted steel needles into its heart to collect its blood. In the face of a powerful machine, its pincer limbs pale and weak.
This is very cruel for horseshoe crabs, which can only weakly watch their blood pass little by little, slowly waiting for death to come. Under uncontrolled fishing, horseshoe crab production is declining, and it is listed as a protected animal by many countries.
Some companies have proposed measures to protect horseshoe crabs, capturing them, drawing 30% of the blood at a time, and then releasing them back into the water to recuperate. This seems to be a win-win situation, but it is not.
Some horseshoe crabs die directly during the blood drawing process, and about 10%-15% of horseshoe crabs die. Most horseshoe crabs put back into the water are languishing and more than half of them have reduced fertility. About 20 percent of horseshoe crabs also die soon after returning to the waters. This act of drawing blood and releasing it has had a devastating impact on the increase in the number of horseshoe crab groups.
Moreover, horseshoe crabs are monogamous creatures, and during the breeding season they go en masse to the beach to lay their eggs, which exacerbates the existential crisis. About 10% of horseshoe crabs will roll over when they are pushed ashore by waves, and once the body is turned over, it is difficult to recover. They basically die from sunlight, and horseshoe crabs die from rollover each year.
A horseshoe crab grows for at least 15 years from juvenile to maturity, during which time the male shells 18 times and the female 19 times.
Difficulties in breeding, combined with increasing catches, have led to higher prices for horseshoe crabs. Especially in 2020, when the epidemic broke out, the blood price of a liter of horseshoe crab reached a terrifying 100,000 yuan.
In the face of such high prices, many people have ignored the government ban and caught a large number of horseshoe crabs, which has further reduced the number of horseshoe crabs.
Under multiple effects, the number of horseshoe crabs has become extremely rare. It used to be seen everywhere on the beach, and the inhabitants of the sea used to use it as food. It is said that the taste is not good, and it is easy to be poisoned by heavy metals if you eat too much. Now, it's almost impossible to see a horseshoe crab quietly in wild waters.
The horseshoe crab, which has become an endangered animal, is worth pondering. It's chilling that horseshoe crabs have solved our reagent safety problems and are treated like this. Judging the value of an animal should not be useful to us, let alone cruelly hunt and draw blood for profit.