Vaquitas are the smallest and most endangered species of the cetacean order and are endemic to the northern end of the Gulf of California. The vaquita is somewhat stocky and has a classic porpoise shape. The species is distinguishable by the dark rings surrounding their eyes, patches on their lips, and a line that extends from their dorsal fins to their mouths. Their backs are a dark grey that fades to white undersides. As vaquitas mature, the shades of grey lighten. Female vaquitas tend to grow to be a bit larger than the male. Females usually end up at a length of 140.6 cm (55.4 in), compared to the males at 134.9 cm (53.1 in). The lifespan, pattern of growth, seasonal reproduction, and testes size of the vaquita are all similar to that of theharbour porpoise. The flippers are proportionately larger than other porpoises and the fin is taller and more falcated. Theskull is smaller and the rostrum is shorter and broader than in other members of the genus. The females are discernible from the males due to their larger size.