Whilst on the water this morning we also encountered a group of Dall's Porpoise. This uniquely marked, black and white porpoise was named after the American naturalist W. H. Dall, who collected the first specimen of the type, which is now on display in the U. S. National Museum. It may be the fastest swimmer of all the small cetaceans and has been reported to reach speeds of 30 knots. It delights in bow riding with fast-moving vessels. As the porpoise dashes in at high speed, its head and back produce a bow wave called a "rooster tail", which creates a hollow cone allowing the animal to breathe while still under the surface of the water.
This cetacean is quite small, averaging 6 feet (1.8 m) for males with a maximum length of 7.5 feet (2.29m). Females average 6 feet (1.8 m) with a maximum length of 7 feet (2.1m). Weight averages 270 pounds (123 kg) for both males and females. Possible maximum weight is about 350 pounds (160 kg).
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