At Associates of Cape Cod located in Falmouth, MA, lab technicians remove the blood from horseshoe crabs for pharmaceutical purposes via direct vein puncture. The process begins with local fisherman who collect the crabs which are stored live in corrals then transferred in trash barrels by the truckload to the laboratory. The crabs are placed on special racks and the blood is removed with large-bore needles and then processed. The processing creates a disgusting protein byproduct similar in consistency to slime/silly-putty which tenaciously sticks to everything especially the tons of lab glassware which subsequently needs to be washed by hand. The main product, a solution used for bacterial testing, is bottled and freeze-dried.
Ironically, the whole process takes place in a "clean" environment to avoid contamination of the product. Workers must wear hot tyvek suits and the whole place stinks like fish. The process ends with the crabs being returned to the ocean - yes, they survive the process (more or less) or they are used by the fishermen for bait. The process is time sensitive due to the seasons and migratory habits of the crabs, so bleeding always takes place in mid-summer.