Description
The blue whale is a slender-bodied cetacean with a broad U-shaped head; thin, elongated flippers; a small 33 centimeters (13 in) sickle-shaped dorsal fin located close to the tail, and a large tail stock at the root of the wide and thin flukes. The upper jaw is lined with 70–395 black baleen plates. The throat region has 60–88 grooves which allows the skin to expand during feeding.[6][7][36][37][38] It has two blowholes that can squirt 9.1–12.2 meters (30–40 ft) up in the air.[6][36][37] The skin has a mottled grayish-blue coloration, appearing blue underwater.[7][36][37] The mottling patterns near the dorsal fin vary between individuals.[39][40][41] The underbelly has lighter pigmentation and can appear yellowish due to diatoms in the water,[7][36][37] which historically earned them the nickname "sulphur bottom".[12][42] The male blue whale has the largest penis in the animal kingdom, at around 3 m (9.8 ft) long and 12 in (30 cm) wide.[43]