does a blue whale have a dorsal fin
The dorsal fin is small; its height averages about 28 centimetres (11 in), and usually ranges between 20 and 40 cm (7.9 and 15.7 in), though it can be as small as 8 cm (3.1 in) or as large as 70 cm (28 in). It is visible only briefly during the dive sequence. Located around three-quarters of the way along the length of the body, it varies in shape from one individual to another; some only have a barely perceptible lump, but others may have prominent and falcate (sickle-shaped) dorsals. When surfacing to breathe, the blue whale raises its shoulder and blowhole out of the water to a greater extent than other large whales, such as the fin or sei whales. Observers can use this trait to differentiate between species at sea. Some blue whales in the North Atlantic and North Pacific raise their tail fluke when diving. When breathing, the whale emits a vertical single-column spout, typically 9 metres (30 ft) high, but reaching up to 12 metres (39 ft). Its lung capacity is 5,000 litres (1,300 US gal). Blue whales have twin blowholes shielded by a large splashguard.
Blue whale