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Pacific Whitesided Dolphins

















What is taxonomy?

Pacific whitesided dolphins often jump, somersault, and spin in midair.  These dolphins are seen in groups ranging from a few hundred to thousands of animals  in the temperate North Pacific Ocean. 

Interesting Facts:

  • Pacific whitesided dolphins (and all dolphins) are extremely fast swimmers.  They often ride the bow waves of ships and sometimes even overtake slow ships.
  • It is believed that all dolphins sleep with half a brain. No joke!  When a dolphin such as a Pacific whitesided dolphin sleeps, half of its brain rests while the other half stays awake to allow the dolphin to function normally.  Later, the two halves of the brain switch functions while the other side rests.  This half-brained sleeping prevents dolphins from drowning while asleep.

What should I know about Pacific whitesided dolphins?

Where do Pacific whitesided dolphins live?

Pacific whitesided dolphins inhabit the temperate Northern Pacific Ocean north of the coasts of Japan and Baja California, Mexico, and across the North Pacific between the latitudes of 38°N and 47°N.  They range from the open ocean to nearshore waters. 

How many Pacific whitesided dolphins are there?

Pacific whitesided dolphins are not considered endangered. You can read more about Pacific whitesided dophin stocks in the NMFS Alaska and Atlantic stock assessment reports.

How can I identify a Pacific whitesided dolphin?

Pacific whitesided dolphins grow to be about 7.5 feet (2.3 meters) long and are marked by distinctive color patterns.  Their backs are dark gray or soft black, their sides are light gray and their belly is white.   They have a white or light gray stripe along their sides that is sometimes referred to as "suspenders."  Pacific whitesided dolphin beaks, the front edge of their dorsal fins, and their flukes and flippers are all dark.  Pacific whitesided dolphins have a unique bicolored dorsal fin.  Pacific whitesided dolphins have 21-28 teeth in each jaw and their beaks are short, but well-defined. 

How well can a Pacific whitesided dolphin  see or hear?

All dolphins, including the Pacific whitesided dolphin,  have strong eye muscles that can change the shape of the eye lens in order to focus in both air and water.  Dolphins can recognize some colors and their pupils can adjust to light and dark changes in their environment.   Dolphins have a well-developed sense of hearing and navigate their environments through echolocation.   Dolphins have very sensitive skin, which is easily damaged but also heals quickly. 

What do Pacific whitesided dolphins eat?

Pacific whitesided dolphins are known to consume hake, anchovies, squid, and sardines. Instead of using their teeth to chew their food, dolphins grip food with their teeth, then swallow it whole--head first--so the spines of the fish don't catch in their throats. 

How do Pacific whitesided dolphins have their young?

Pacific whitesided dolphins mate during the late summer and early fall.  Approximately 3 foot (0.9 meter) calves are born after a 11.6 month gestation period, and calves are nursed for a year plus after their birth.  Female dolphins can bear a calf every two years but generally give birth every three years. 

How long do Pacific whitesided dolphins live? How do they die?

No one really knows the average life span of a Pacific whitesided dolphin however, it is believed to be anywhere between 36 and 40 years.  Pacific whitesided dolphins are sometimes preyed upon by killer whales, are caught incidentally in drift nets and gill-nets, and some countries harvest them for food. 

Where can I find more information about Pacific whitesided dolphins?

Books and the world wide web are excellent places to learn more about marine mammals. 


  • Leatherwood, Stephen. Reeves, Randall R. Foster, Larry.   The Sierra Handbook of Whales and Dolphins.  Sierra Club, San Francisco, CA.  1983.
  • Leatherwood, Stephen.  Reeves, Randall R. Perrin, William F.   Evans, William E.  Whales, Dolphins, and Porpoises of the Eastern North Pacific and Adjacent Arctic waters; A Guide to their Identification.  Dover Publications, Inc., New York, NY.  1988.
  • Wynne, Kate. Folkens, Pieter. Guide to Marine Mammals of Alaska.  Alaska Sea Grant Program.  University of Alaska Fairbanks, Fairbanks, AK.  1992. 

World Wide Web

There are many more sources to learn about cetaceans.   Check with MML's online library or your local librarian for her or his recommendations.

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This portion of the MML website is intended for a student audience and their educators.
Information within the education website should not be cited in scientific journals or publications.

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