Pike scale (Esox lucius) 插畫檔

Pike scale (Esox lucius). It shows the microscopic structure used by biologists to determine the age and growth history of the fish.Circuli: The fine, concentric rings visible across the scale are called circuli. As the fish grows, it adds these rings to the edge of the scale.Annuli (Growth Rings): Similar to tree rings, when a fish's growth slows down (usually during winter), these circuli become more crowded or fragmented, forming a "check" or annulus. By counting these bands, scientists can estimate how many years the pike has lived.Radii: The three prominent V-shaped grooves extending from the center (focus) toward the bottom are called radii. These provide flexibility to the scale so it doesn't crack as the fish moves and bends its body.Orientation: The "tricuspid" (three-lobed) part at the bottom is the anterior portion, which is actually buried under the skin and other scales. The rounded top part is the posterior portion, which is the part visible on the outside of the fish.