By Obiabin Onukwugha
Porpoises are small dolphin-like cetaceans classified under the family Phocoenidae. Although similar in appearance to dolphins, they are more closely related to narwhals and belugas than to the true dolphins.
There are eight extant species of porpoise. Several species exhibit sexual dimorphism in that the females are larger than males.
Porpoises tend to be social and live in groups. They use echolocation as their primary sensory system.
Echolocation, also called bio sonar, is a biological active sonar used by several animal groups, both in the air and underwater. It is used for navigation, foraging, and hunting prey.
Some species are well adapted for diving to great depths. As all cetaceans, they have a layer of fat, or blubber, under the skin to keep them warm in cold water.
Porpoises are abundant and found in a multitude of environments, including rivers, coastal and shelf waters and open oceans.
Porpoises feed largely on fish and squid, much like the rest of the odontocetes.
However, scientists say little is known about reproductive behaviour. Researchers note that females may have one calf every year under favourable conditions, born in the spring and summer months and remain dependent on the female until the following spring.
Porpoises, like dolphins are at the top of the food chain and play an important role in the overall balance of the marine environment. These animals are often referred to as “sentinels” of ocean health providing insight into marine ecosystem dynamics.
Numerous studies have explored the effects of noise and chemical pollution, habitat degradation, and changes in climate on these animals.
Porpoises are also protected under the Marine Mammal Protection Act, and some are also listed under the Endangered Species Act.
The life span of a harbor porpoise is typically eight to 10 years, but they can live to be 20 years of age.
According to Native-languages.org, “Porpoise are occasionally used as a clan crest or totem in Northwestern tribes, such as the Tlingit Porpoise Clan, called Chookaneidi or Chukanedi in Tlingit. Porpoise can sometimes be found carved on totem poles in these cultures.