Description: The body of the common thresher shark is moderately elongate. The snout is rather short, and the mouth crescent shaped. The first dorsal fin is large, and located midway between the pectoral and ventral fins. The second dorsal and anal fins are very small. The tail is distinctive since it is very long, almost as long as the rest of the body. The coloration may vary from brownish gray, bluish or blackish above to silvery, bluish or golden below. The dorsal, pectoral and ventral fins are blackish and sometimes the pectoral and ventral fins have a white dot in the lip. The bigeye thresher also occurs off the California coast. It can be distinguished by its large eye; however, if you can count the teeth in the upper jaw, the common thresher has 21 - 22 on each side while the bigeye thresher has 10 - 11 on each side.