Question

what is the blood colour of crab
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Answer 1

Blue is the colour of crabs due to presence of copper in hemocyanin

Answer 2

Answer:

BLUE

Their blue blood? That's because copper plays the role in the crabs' blood that iron does in ours. The iron-based, oxygen-carrying hemoglobin molecules in our blood give it that red color; the copper-based, oxygen-carrying hemocyanin molecules in theirs make it baby blue.