The Green Sea Turtle is the sea animal whose blood can sometimes appear green.
While not all Green Sea Turtles consistently have green blood, it can occur due to a high concentration of biliverdin. Biliverdin is a green bile pigment, a product of hemoglobin breakdown. Elevated levels of biliverdin in their bloodstream can impart a greenish hue to their blood. This condition, however, often indicates a health issue.
In short, it's not that green blood is normal for them, but it can happen and is most associated with Green Sea Turtles amongst sea creatures.
