The phrase "blue blood" means someone of aristocratic or noble birth.
The phrase originates from the 17th century, when blue textile dye was expensive and only aristocrats could afford to wear blue clothes.
However, in nature, there is an animal whose blood actually is blue – the horseshoe crab.
Unfortunately, the existence of this 450-million-year-old species is under threat as the crab is being hunted to extinction in the Chattogram region.
The high price of its blood have made horseshoe crabs a prime target for smugglers.
Threatened horseshoe crab population
A powerful international smuggling racket is reportedly involved in smuggling horseshoe crabs from Bangladesh's coastal areas to various countries – including Thailand.
The International Union for Conservation of Nature (IUCN) has included it on its "Red List" of threatened species in Bangladesh.
"Horseshoe crabs are found mostly on sandy and muddy beaches," said Abu Sayeed Muhammad Sharif, senior scientific officer at the Bangladesh Oceanographic Research Institute, Cox's Bazar. He added that rampant use of fishing nets and gear has also contributed to their steep decline.
Joynal Abedin, a resident of Airport Road in Cox's Bazar town, quoting local fishermen, said about 20-to-25 years ago, there were swarms of horseshoe crabs at the Bakkhali River in the Moghchita Para area of the town.
Just 10 years ago, horseshoe crabs were visible at the confluence of the Bakkhali River in the town's Uttar Nuniachhara area. Only four years ago, they could be spotted at Sonadia island but now it is rare to spot one in these areas, he said.
Abdul Qayum, a resident of seacoast at Kumira under Sitakundu upazila in Chattogram, echoed Joynal Abedin's observations. He said swarms of horseshoe crabs can no longer be found at the confluence of the rivers and canals of different sea coasts in Sitakundu.
Noted oceanographer and former district fisheries officer at Cox's Bazar Dr M Kabir Ahmed said due to a decrease in the number of horseshoe crabs on Chattogram's coast the number of migratory birds is also decreasing.
"In winter, migratory birds cross several thousand miles to come to Bangladesh. They eat the eggs of horseshoe crabs for their nourishment, he added."
Expensive blue blood
The blood of a horseshoe crab is expensive because of its wide use in medical science. "The blue blood of a horseshoe crab sells for about US$60,000 [about Tk50 lakh] per gallon [4.5 litres]", said Ashraful Haque, senior scientific officer of Marine Fisheries and Technology Station, Cox's Bazar.
Marine scientist Prof Dr Shahadat Hossain said the crab's unique blood can detect small amounts of bacterial contamination. This blood is used for the detection of bacterial endotoxins in medical applications.
Unlike vertebrates – which have haemoglobin in their blood to transport oxygen throughout their bodies – horseshoe crabs have hemocyanins in their blood. Their blood is blue due to the presence of copper and brass in hemocyanin.
The blood of vertebrates contains white blood cells that detect harmful germs and prevent them from building up.
On the other hand, the blood of invertebrate horseshoe crabs contains amebocytes. It contains a chemical ingredient called Limulus Amebocyte Lysate (LAL).
Usually, the presence of an endotoxin cannot be detected by a blood test. Here the horseshoe crab deserves thanks as the C factor of LAL present in their blood can detect the presence of endotoxins in human blood.
In a laboratory test, by adding C factor to the germ-contaminated blood specimen, scientists find that blood clots around the germ. The drug prepared using the blood of horseshoe crabs helps scientists detect the presence of lethal infections and prevent it from spreading.
Smugglers use sophisticated methods
A number of powerful international rackets have been smuggling the valuable resource out of the country, Fisheries Research Institute sources said.
The gangs include trained and skilled technicians. They have been smuggling horseshoe crabs – and their blue blood – alongside other commodities, via sea routes, they alleged.
A source at the Bangladesh Fisheries Research Institute alleged that some fish farms were also involved in the crime.
At the end of 2019, some aquaculture scientists from Thailand came to Cox's Bazar in search of horseshoe crabs. It is suspected the Thai scientists came primarily to collect horseshoe crab blood, a senior official of the Fisheries Research Institute said.
Horseshoe crabs are caught in the Bay of Bengal and blood is drawn from them after they are brought to shore – using a sophisticated method in laboratories.
The blue blood is then taken to fishing boats by speedboat or trawler. These are consigned on Thailand-bound cargo ships from the fishing trawlers – along with the legs of horseshoe crabs in mid-ocean, sources say.
Apart from sea routes, the blood is smuggled with fish and other commodities.
The fisheries institute source say the government cannot detect the blood smuggling since they lack the necessary technical knowledge.
Prof Dr Sheikh Aftab Uddin said the horseshoe crab has survived for more than 450 million years but it is now critically endangered.
"Once the therapeutic properties of the crab were publicised, it faced the threat of extinction," he said.
He said that in the US, 400 millilitres of blood are collected from adult horseshoe crabs and 50 millilitres from underage crabs. They are then released in nature but about 30 percent of those horseshoe crabs die from weakness and careless handling.
To save the horseshoe crabs in developed countries only 15-to-30 percent of their blood is drawn. However, in many countries, almost all the blood is collected causing many of the crabs to die.
How horseshoe crabs are hunted
Adult crabs come to beaches to lay eggs during their breeding season. They are caught by hunters while returning to the sea after they lay their eggs.
A female horseshoe crab lays 60 thousand to 1 lakh 20 thousand eggs a year, of which a few thousand survive.
Though the habitat of the horseshoe crab has shrunk significantly, a swarm of five to six horseshoe crabs was spotted at the Maheshkhali mangrove forest – opposite Nazirartek in Cox's Bazar town – about one-and-a-half years ago, said, Prof Dr Sheikh Aftab Uddin of the Institute of Marine Science and Fisheries at Chittagong University.
Can they be saved?
There are some measures being taken to save the crab from extinction, Abu Sayeed of the Oceanographic institute said. They have already taken initiatives to save the marine biodiversity of the Saint Martin's Island. There, it is now a punishable offence to disturb endangered sea creatures like coral.
Apart from working from the policymaking level, he also stressed the importance of raising public awareness to save the crab.
The Additional Police Super of Cox's Bazar Md. Iqbal Hossain said, "We know the horseshoe crab is highly sought after globally because of its medicinal value." That's why a gang in the coastal regions and the town hunt these crabs and it is now endangered.
All concerned have been instructed to be vigilant in the coastal and other areas and to take legal actions if anyone is found to be involved in the smuggling of the animal, he added.
The "living fossil" is also becoming extinct in different regions in the world as several crore horseshoe crabs are hunted for use in the pharmaceutical industry.
As the crab population wanes, pharmaceutical industries are trying to find synthetic alternatives to reduce dependence on them.
The encouraging side is that the habitat of the horseshoe crab still exists in some areas of the Bay of Bengal.
"Scientists have not been able to breed the species artificially in enclosures anywhere in the world," said marine scientist Ashraful Haque.
Prof Jahedur Rahman Chowdhury, director of the Institute of Marine Science at Chittagong University said research on horseshoe crabs started in the USA in 1950s but there has been no research on them in Bangladesh.
He added if the species can be saved and used alongside technological advancements, the country's blue economy will be bolstered.
Horseshoe crabs are not actual crabs
In the greater Chattogram region – including Cox's Bazar – the horseshoe crab is more commonly known as the "Raj kakra."
Though the species is known worldwide as a crab, scientists believe that the marine animal is related to an extinct species of sea scorpion.
Marine scientist Ashraful Haque said while there are four kinds of horseshoe crabs in the world, the Tachypleus tridentatus and Tachypleus giga species are found in this region.
However, he said these species are also rare.