Wildlife of the Week!

©Five Star Whale Watching/ Andrew Lees. A Dall’s porpoise is seen racing through the waves of the Salish Sea; it was likely the expulsion of water from the animal’s fast surface swimming produced what is known as a “rooster tail”.

How is everyone’s long weekend? It seems to us like the weekend is already flying by as fast at this Dall’s porpoise! The Dall’s porpoise may often be confused with the Killer Whale, but it is in fact very different than its larger dolphin relative. Baleen whales and toothed whales (includes dolphins and porpoises) have common similarities, but many differences as well. What are some physiological and behavioural differences between a dolphin and a porpoise? Share your comments below.

The Dall’s porpoise is small in cetacean terms, measuring only between 6-7.5 feet (1.8-2.3m) long. It is a truly unique species of porpoise with a certain level of charisma we have all come to know. The species is an agile, playful and fast-moving cetacean capable of reaching speeds up to 55km/ hour (34m/hour or 30 knots). They typically weigh only a few hundred pounds at most (up to 250 pounds, 123 kg). 

The Dall’s porpoise is muscular and they are a relatively thick-bodied porpoise with a rotund shape and blunt face. As compared to dolphins, porpoises typically have a less pointed beak and melon area. 

The most obvious characteristic of the Dall’s porpoise is perhaps their Killer-Whale reminiscent black and white patterning. The dorsal fin and flukes of the Dall’s are white-tipped, and they have a forward facing oval white patch on their belly and up each side. A noticeable feature is a small hump located between their dorsal fin and tail region. 

Dall’s porpoise may be coastal, pelagic, nearshore or offshore distributed and are most often found in several temperate and northern regions. On the West Coast, they range from Baja California, Mexico to Alaska. They are also found from the Bering Sea to the coast of Japan. 

The Dall’s porpoise is believed to primarily feed in the evening, as their prey migrates to the upper levels of the ocean. They sustain themselves on sardines, herring, hake, lanternfish and squid and even crustaceans. This prey is slippery, but dental adaptations help the animal to grasp its food. Their teeth are small, sharp and conical with ridges between them; this tooth shape is often characteristics of porpoises. 

Dall’s porpoise may live between ages 15-20 (normally), reaching sexual maturity at about 3.5- 8 years; the calf is usually in gestation for a little under a year to a year and is nursed for under a year. 

In the Salish Sea, Dall’s porpoise must be on the watch for predators such as Bigg’s (transient) Killer Whales that will seek to hunt them for prey. Dall’s porpoise may form short relations with dolphins and other whales. They are frequently seen to seek out the large waves created by a ship, and “bow-ride”. The explosion of water from their swimming movements and body create a unique “rooster tail” in their wake. 

Interestingly enough, you may one day spot a Harbour/ Dall’s porpoise hybrid. It would certainly be more challenging to identify that porpoise for a beginner! 

If you’re feeling confident about your porpoise know-how, try out some trivia below!

  1. How many teeth may be found in a Dall’s porpoise’s mouth? (ANS: 38-56). 
  2. True or False? Dall’s porpoise are only ever found alone. (ANS: FALSE. Dall’s porpoise may be observed in groups of 2 to several thousand). 
  3. True or False? Dall’s porpoise may dive to depths of over 1,600 feet. (ANS: TRUE. They can reach diving depths of 1,640 feet).

BONUS CHALLENGE:

The Dall’s porpoise, like other toothed cetaceans, may use variable underwater vocalizations to locate prey and navigate their surroundings. This process is called ______. 

echolocation. 

Author: Alexa Desautels/ Five Star Whale Watching.

August 2nd, 2020.

If you want to learn even more about this special species, visit our References to learn more!

1.”Dall’s porpoise.” American Cetacean Society. https://www.acsonline.org/dalls-porpoise

2. “Dall’s porpoise.” NOAA Fisheries. National Oceanic and Atmospheric Administration. U.S. Department of Commerce. https://www.fisheries.noaa.gov/species/dalls-porpoise

Leave a Reply

Your email address will not be published. Required fields are marked *