Porpoises are marine mammals and are part of the cetacean species which also includes dolphins and whales.
So far there are currently around 6 known species of porpoises in existence today.
Out of all three groups porpoises are the smallest of the cetaceans with an average size of between 5 – 8 ft. in length and an average weight of between 100 – 200 lbs., however it is possible for some porpoises to weigh in excess of 400 lbs when fully grown.
Although porpoises are able to dive to depths of over 650 ft. when searching for food they usually stay at or near the surface of the water.
When startled or surprised some species of porpoise are known to reach speeds in excess of 30 miles per hour in order to help them escape from a potential threat or predator.
Physical Characteristics
When it comes to physical characteristics porpoises have a shorter, stockier build than dolphins and appear to have a rotund shape.
As stated earlier they typically grow between 5 – 8 ft. long and weigh between 100 – 200 lbs. with the largest porpoises weighing over 400 lbs.
Porpoises tend to be the thickest near the center with their body tapering down towards the flukes.
The head is rounded with a very short beak and the neck is short and immobile (fused) whereas dolphins on the other hand have un-fused necks that allow them to turn their head in multiple directions.
To assist them with grabbing their prey porpoises have a short mouth with spade shaped teeth.
Swimming is performed by arching their back, tail and flukes up and down to propel themselves forward while steering with a pair of flippers that taper back towards the end.
The small triangular-shaped dorsal fin located on its back helps the porpoise maintain stability while traveling through the water.
In terms of color most porpoises are varying shades white, gray, brown and/or black and some porpoises have multiple colors.
Species such as the harbor porpoise have dark gray or dark brown coloring with a white belly.
Diet
In terms of diet porpoises are known to consume fish, squid, and crustaceans as part of their primary food sources.
To assist them with locating prey porpoises hunt for food using echolocation.
In addition to helping them find food echolocation also helps them navigate the ocean in areas where light is absent and keep track of other pod members.
Although porpoises are predators they prefer to hunt in shallow coastal waters and usually hunt for food near or at the surface of the water.
Hunting in shallow coastal waters helps these marine mammals avoid attacks from potential predators since they are smaller than other cetaceans.
Due to the porpoises small size it requires frequent eating in order to maintain its energy and body heat as compared to some of the larger cetacean species that can reserve large amounts of energy which they store in their fat/blubber.
Migration
When it comes to migration porpoise aren’t known to make long migration trips, however they may be seen migrating to different locations within their coastal environments.
Some populations may migrate away from the coastline during the colder winter months when their local habitat freezes over and travel back once the water warms up.
Other populations may migrate based on their dieting needs and where the most abundant supplies of food can be found.
Migrations may include travel towards and away from coastal waters and from coastal waters to large rivers depending on the situation.
Social Structure
Unlike some dolphin species, porpoises appear to be less social and tend to avoid interacting with humans or boats.
They usually prefer to live in small groups of 10 or less but can aggregate into groups of several hundred during times of feeding or during certain social interactions.
Porpoises aren’t nearly as energetic as dolphins when it comes to showing off and prefer to be more reserved when it comes to things such as leaping and jumping, however they do appear to be more sexually aggressive than dolphins.
Due to the fact that porpoises stay to themselves and travel in small groups it is hard for scientists and researchers to develop significant research on the topic of porpoises and their social structure.
Breeding
The average gestation period for a porpoise (the period between conception and birth) is about 10 – 11 months.
Most female porpoises reproduce once every 1 – 3 years while fertile.
After birth the child will be nursed by its mother and fed milk until it is able to hunt and consume solid foods.
Sexually maturity for porpoises usually occurs between the ages of 3 – 5.
Once sexually mature the porpoises will begin reproducing their own offspring.
While sexual maturity comes early in life these marine mammals have a relatively short lifespan.
When compared to other cetaceans that are able to live between 25 – 200 years (depending on species) porpoises only live till around 10 – 20 years of age on average.
When looked at from this perspective a porpoise may have already lived 30% – 50% of its life when it begins reproducing.
Threats
Although porpoise are a protected species these marine mammals are known to be hunted for food or as bait for other marine animals.
In commercial areas porpoises may end up getting caught in fishing nets or other types of fishing equipment.
They may also become sick due to oil or other toxic chemicals that are spilled into the water.
10 Spectacular porpoise facts
- There are currently six known species of porpoise which include Burmeister’s porpoise, Dall’s porpoise, the Finless porpoise, the Harbor porpoise, the Spectacled porpoise and the Vaquita.
- Porpoises are marine mammals which means they are warm-blooded, give birth to live young, breathe air and produce milk to feed their children.
- These marine mammals are equipped with echolocation which allows them to navigate the ocean and search for food; even in complete darkness.
- The porpoise species makes up six of around eighty known species of cetacea. As stated earlier cetaceans include all species of whale, dolphin and porpoise.
- Porpoise are known to face threats from natural predators such as killer whales and sharks.
- These marine mammals (along with all cetacean) are a protected species and hunting them in certain countries is considered illegal and can lead to steep fines and jail time.
- Dall’s porpoise has been recorded swimming at speeds in excess of 32 mph making it one of the fastest known cetaceans in existence.
- The most popular and well-known species of porpoise is the harbor porpoise as they are abundant and often found swimming near the harbor and in coastal waters.
- The smallest species of porpoise is the Vaquita porpoise which measures in at around 5 ft. long. It is also one of the rarest species of known cetacea.
- Porpoises are extremely intelligent and are able to learn how to perform various tricks and complete specific tasks when taught by a trainer.