Final answer:
Bivalves have colored blood, which can vary in color depending on the species. The variation in blood color is due to the presence of different pigments.
Step-by-step explanation:
Bivalves have colored blood. The color of the blood in bivalves can vary depending on the species. Some bivalves have blood that is a reddish or burgundy color, while others have blood that is blue or green. This variation in blood color is due to the presence of different pigments, such as hemoglobin or copper-based hemocyanin, which help transport oxygen throughout the body.