The earth is a big stage, where the ups and downs of life are constantly being played out. Whenever the story is calm, it will try its best to set off a huge wave.
When the gamma rays generated by the supernova hit the earth, 75% of the marine life went extinct; when the super mantle plume erupted, 96% of the marine life went extinct; when the asteroid hit the earth, the dinosaurs that ruled the earth for 160 million years were wiped out.
Big waves wash away the sand, and some lives come and go, including odd shrimp , Deng's fish , Mosasaurus and other marine overlords have gone extinct one after another, the marine ecosystem has undergone many great changes, and those who can escape an extinction are very lucky , while some animals have escaped all mass extinctions, and continue to this day, it is the horseshoe crab (hòu).
limulus
The miracle that lasted for 500 million years
Of course there is, aside from simple single-celled organisms such as cyanobacteria , the horseshoe crab is undoubtedly one of the longest-lived animals.
It is an arthropod born 500 million years ago ( Ordovician ). Today's horseshoe crabs are almost the same in shape as the fossils of the Jurassic period. Their bodies are broad horseshoe-shaped, because the shape is similar to horseshoes. , so it is also called horseshoe crab , but they are not actually crabs, but closer to scorpion, trilobite .
It moves in the water by plucking the gills on its abdomen, and has a long, pointed tail sword on its tail. Despite its majestic appearance, this animal is not as effective as a crab, feeding only on worms, thin-shelled mollusks , and sometimes carrion. It is such a weak animal that was once the overlord in the ocean .
Male horseshoe crab (left) female horseshoe crab (right)
The oldest plate-footed horseshoe crab (also called sea scorpion) was born in the Ordovician period. It is quite different from today's horseshoe crab in shape. They are closer to the tail without a long tail. Barbed scorpion, body length of 1.5m. At that time, there were no continents on the earth, and marine plants had just appeared. Trilobites, brachiopods, and echinoderms were the most common. The straight-shelled nautilus with a length of 8 and 9 meters was a ferocious marine carnivore in this period.
The 10m-long straight-shelled parrot
plate -legged Limulus was originally suppressed by the straight-shelled nautilus, but everything changed because of the first mass extinction of the earth in the late Ordovician.
The plate-footed horseshoe crab that turned over due to mass extinction
.449 billion years ago, a neutron star collided with a black hole for unknown reasons, resulting in a gamma-ray burst , one of which hit the earth impartially, the rays It destroyed the earth's atmosphere and destroyed 1/3 of the ozone layer. The strong ultraviolet rays caused the death of a large number of plankton, and directly changed the ecological environment of the earth, causing 56% of species to become extinct.
The trilobite fossil
The straight-shelled nautilus miraculously survived, but a bad gene mutation occurred, and the body size was reduced to 2 meters. After the disaster, it quickly replaced the straight-shelled nautilus and became the top predator, becoming the largest individual species of marine arthropods in the Silurian era.
However, this domination lasted only a few thousand years. With the rise of various fish in the Devonian era, the era dominated by arthropods and mollusks officially came to an end, some horseshoe crabs went extinct, some survived down.
Comparison of the size of the plate-footed horseshoe crab and the nautilus
In today's lively ocean, the modern horseshoe crab has long lost its dominance, but they escape the predation of many fish with their hard spiny shells, and have a 40-50m shallow water area. One place, their main predator is the loggerhead sea turtle, but this turtle is now an endangered animal, their real predator is someone else.
It was obviously unpalatable, but it was fooled into the dining table.
The horseshoe crab entered the Chinese recipe from a very early age. According to the Compendium of Materia Medica:
The horseshoe crab is shaped like a crown of Huiwen and an iron, and it is wider than a foot. Its armor is smooth blue-black. The back bone has eyes, the mouth is under the abdomen, and the head is like a dung beetle. Twelve legs, like crabs, with stems on both sides of the abdomen. The back has bones like horns, seven or eight inches high, like a stony coral. Every time we cross the sea, we are called horseshoe crabs. Its blood is blue. Belly has sub- such as millet, can be glutinous sauce.
The eggs of the horseshoe crab
"Ling Table Records of Differences" records how people in Lingnan eat horseshoe crabs: there is a seed in the abdomen such as mung bean, the southerners take it, break its feet, and eat it as a sauce.
It can be seen that the Lingnan people have had the habit of eating horseshoe crabs from a very early time. Today, the cooking methods of horseshoe crabs vary from place to place. There are for soup and for barbecue. It is also recorded in the book: "The little ones are called ghost king crabs, and eating them will harm people." It can be seen that the ancients also discovered some side effects of eating king crabs.
The surface of modern research: Limulus meat contains macromolecular non-specific protein allergenic substances and endocyclic amide purine chemicals. Eating Limulus can cause allergic skin rashes, redness and itching, and in severe cases, allergy. Shock or lethal toxicity, poisoning has a higher mortality rate, and there is a risk of severe gout.
Fun Limulus
In addition, the taste of Limulus is very general, with a strong fishy smell and meaty wood, but even so, there are still many unscrupulous traders in order to make money. threaten.
Blue blood, causing death
The feeding of horseshoe crabs is only one of the reasons for the decrease in the number of horseshoe crabs. As early as in the colonial period of America , people used "limulus fertilizer" to fatten the land. Millions of horseshoe crabs are caught, crushed into fertilizer, and some are made into pig feed.
Farms use horseshoe crabs as fertilizer
In modern times, people have better fertilizers and understand the dangers of eating horseshoe crabs. The horseshoe crabs, which should have retired gloriously, have ushered in a real nightmare.
In 1956, when a scientist named Frederic was studying the blood circulation of the horseshoe crab, he found that a horseshoe crab died strangely. This horseshoe crab was infected with the Gram-negative bacteria in a large area. It condensed into a colloid, which intrigued him.
The study found that horseshoe crabs have a magical amoeba-like cell in their blood. When they encounter a virus, this cell will rupture and release an enzyme that causes the blood to coagulate, thereby killing the virus. Using this characteristic of limulus blood, scientists have invented the use of the blue blood of limulus as a virus detection reagent.
Limulus live blood
With this reagent, people can easily test various injection drugs for bacteria, instead of using rabbit (rabbit is very sensitive to toxins, but the test time is long) for testing, because of its unique Due to its biological characteristics, this reagent was soon used on a large scale in medicine, and the price of horseshoe crab blood began to soar. About 1 liter of horseshoe crab blood could be worth as much as $15,000, and its price was no less than gold.
Every year, more than 500,000 horseshoe crabs are taken for blood. Although they are released after the blood is taken, 10% to 30% of the horseshoe crabs will die after the blood is taken, but some of them are lucky. More The horseshoe crab continued to be squeezed out of the remaining value after being blooded.
Changes in the value of Limulus
In the 1980s, Limulus-based virus detection reagents began to develop in China, and we also started the R&D and production of the related Limulus reagent . The blood-drained Limulus was either sent to the table, or was With the production of chitin , smart people think they have squeezed all its value, but ignore its deeper value.
As a creature that has survived for nearly 500 million years, it can be said to be "living fossils in living fossils ". They are close relatives of trilobites and are precious materials for studying the evolutionary history of animals.
Limulus fossil
Limulus was first used as an ingredient, and then as a reagent. Before we fully understood its value, we couldn't wait to kill the chicken and retrieve the eggs. We tried every means to squeeze its final value, but it was only after a hundred years that we found that we are even the most fundamental The value is not clear, this is really the biggest joke.
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