7 Sealife Wonders whose blood isn't red, and here's why?

Octopus - Their blood is blue due to the presence of hemocyanin, which contains copper instead of iron. –

Horseshoe Crab - Their blood is blue, also due to hemocyanin, and contains a unique clotting agent used in medical research.

Sea Slug (Nudibranch) - Their blood is often blue or green because of different respiratory pigments.

Brachiopod - These marine animals often have blue blood due to hemerythrin, which contains iron but turns purple when oxygenated.

Peanut Worm (Sipuncula) - Their blood can be green due to chlorocruorin.

Sea Anemone - Some sea anemones have greenish blood due to different pigments.

Sea Spider (Pycnogonid) - Their blood can be yellowish due to unique pigments.