what is the color of horseshoe crab blood
Horseshoe crab Horseshoe crabs use hemocyanin to carry oxygen through their blood. Because of the copper present in hemocyanin, their blood is blue. Their blood contains amebocytes, which play a similar role to the white blood cells of vertebrates in defending the organism against pathogens. Amebocytes from the blood of L. polyphemus are used to make Limulus amebocyte lysate, which is used for the detection of bacterial endotoxins in medical applications.[19] This means there is a high demand for harvesting the blood, which involves collecting and bleeding the animals, and then releasing them back into the sea. Most of the animals survive the process; mortality is correlated with both the amount of blood extracted from an individual animal, and the stress experienced during handling and transportation.[20] Estimates of mortality rates following blood harvesting vary from 3-15%[21] to 10-30%.[22] Approximately 500,000 crabs are harvested annually.[23]
Japanese spider crab The Japanese spider crab has the greatest leg span of any arthropod, reaching up to 5.5 metres (18 ft) from claw to claw.[5] The body may grow to a size of 40 cm (16 in) in carapace width and the whole crab can weigh up to 19 kilograms (42 lb)[6]—second only to the American lobster among all living arthropod species. The males have the longer chelipeds;[7] females have much shorter chelipeds, which are shorter than the following pair of legs.[8] Apart from its outstanding size, the Japanese spider crab differs from other crabs in a number of ways. The first pleopods of males are unusually twisted, and its larvae appear primitive.[1] The crab is orange, with white spots along the legs.[9] It is reported to have a gentle disposition, despite its ferocious appearance.[9] The Japanese name for this species is taka-ashi-gani literally translating to “tall legs crab.” Their armored exoskeletons help protect them from larger predators such as octopuses, but giant spider crabs also use camouflage. The crab's bumpy carapace blends into the rocky ocean floor. To further the illusion, a spider crab will adorn its shell with sponges and other animals.[10]