Horseshoe crabs mating, north shore of Fishers Island, June 15, 2020. The male, smaller than the female, latches onto her shell and fertilizes tens of thousands of pearly green, birdshot-sized eggs that she drops into holes she digs while dragging him up the beach to the high tide line. Often, multiple males will try to latch on, completing for fertilization rights. Tom Sargent Photo

The horseshoe crab mating season is over for 2020, adding a new generation to its 450-million-year lineage on earth. With COVID-19 raging, the existence of these “living fossils” is more critical than ever.

For the past three decades, drug companies have depended on a component in the blue blood of horseshoe crabs to test for bacterial contamination during the manufacture of every implanted medical device, every shot, every IV drip destined to go inside the human body. This includes all vaccines under development and billions of doses that will go into production to fight COVID-19.

The blue blood product can detect E. Coli and salmonella, for example, but does not kill it. Instead, it envelopes bacteria with a jelly-like coating, signaling to scientists the presence of harmful endotoxins that live on the walls of bacteria.

There has long been a push from environmentalists who want to protect the horseshoe crab, which is listed as “near threatened” by the International Union for Conservation of Nature. A synthetic version of this protein has been approved for use in Europe but this year was rejected for routine use in the United States.

“It is crazy to rely on a wild animal extract during a global pandemic,” said Ryan Phelan, head of the nonprofit Revive and Restore, which supports technological solutions to conservation problems.

Drug companies drain 30 percent of blue blood from nearly 500,000 horseshoe crabs each year for a clotting agent used to make a liquid called Limulus amebocyte lysate (LAL). The synthetic product is rFC. The price of LAL is reportedly $15,000 a quart.

The Lonza Group, a Swiss biotech company, has made a deal to supply LAL to Moderna, the company already testing a potential coronavirus vaccine. Lonza said five billion doses of vaccine would require “less than a day’s combined production for all three LAL manufacturers in the United States.”

It is estimated that 70 million endotoxin tests are performed annually, making the harvesting of horseshoe crab blood a multimillion-dollar industry.

FACTS: Horseshoe crabs…

…have two copper atoms in their blood, which causes the blood to be blue.

…are not crabs. They are arachnids, a class of arthropods with scorpions and spiders.

…often do not make it to the larval stage before being eaten by numerous birds, reptiles and fish.

…swim upside down, can go a year without eating and can endure extreme temperatures and salinity.

…die at a rate of up to 30 percent after blood harvesting. Most are returned to the ocean, although scientists surmise that some companies likely sell the horseshoe crabs as fishing bait instead.

Horseshoe crabs being bled at Charles River Laboratory in Charleston, S.C. Timothy Fadek/Corbis/Getty