Do crabs have blood???

Question

i've wondered this and feel stupid for asking, but do crabs have blood???

Answer 1

Crabs (and all other arthropods, like flies and spiders) have a watery fluid called hemolymph which fills the inside of their shell. The internal organs float freely in this fluid which is like something half blood and half sweat. Like sweat, it is a mixture of water and various electrolytes like salt and soda. Like blood, it has oxygen carrying proteins, but they are not bundled into cells like they are in things like humans and cows. The oxygen carrying proteins float freely in the hemolymph and are frequently based on Copper instead of Iron. This is why hemolymph is often blue. This fluid is kept circulating by the contractions of the arthropod's legs and a long, tubular heart which is open ended and runs along the arthropod's back. It sucks fluid in at the tail end and passes it to the head end, sort of like an aquarium water pump.  

Answer 2

Yes, crabs have blood, however their blood is blue in color. This is because the protein that transports oxygen in their blood is hemocyanin, which uses copper. Oxidized copper is blue, hence the blue color of their blood.

Red-blooded animals have hemoglobin which uses iron. Oxidized iron is red.

Answer 3

Yes they do. Their blood color ranges from blue to colorless based upon what type of crab it is.

Not a dumb question at all.