total length

the greatest length of the whole body between the most anterior point of the body and the most posterior point, in a straight line, not over the curve of the body. Sometimes, when there are two equal lobes, the caudal rays are squeezed together and their tip is taken as the most posterior point, or the longest lobe is squeezed to the midline (maximum length or extreme tip length). Also an imaginary line may be drawn between the two lobe tips and length to its mid-point taken as the most posterior point (total auxiliary length or bilobular length). Usually the tip of the most posterior lobe of the fin in normal position is taken as the posteriormost point (total normal length or natural tip length). Total length is used in Amphioxi, Myxini, Petromyzontiformes, usually in Elasmobranchii and sometimes in other fishes. Standard length, q.v., is usually employed with Teleostei. Abbreviated TL