Feature photo above is of a school of Pacific white-sided dolphins in Queen Charlotte Sound off Vancouver Island courtesy of Rolf Hicker
By Elizabeth Trickey
Dolphin with calf by Jessica RedfernApril 14th is National Dolphin Day! On this date, we are encouraged to celebrate these animals for their intelligence and positive social interactions. And for all you readers who are wondering why dolphins would be part of our wildlife education series, it is because these mammals aren’t just found in warm, southerly oceans. Canadian waters do play host to these intelligent animals, some of which I will describe in this article. Although many “Delphinidae” (their Family) are not at risk, they are valued by our government and protected by Marine Mammal Regulations.
Most of us are not very familiar with large aquatic animals since we rarely have the opportunity to view them in the wild. To start with, dolphins are not fish. They are mammals, like humans, giving live birth, producing milk for their babies, and they breathe via lungs, not gills. Another distinction I would like to make is that although they are similar in habitat, shape and size of sharks, they are very different animals, belonging to both a different Class and different Order. I am sure that when people think of a shark, they envision a big mouth with hundreds of sharp teeth coming right for them! Most sharks have 5 rows of razor sharp teeth, about 3000 of them, that are replaced each time one is lost! But not so for the dolphin which has far fewer teeth that have to last a lifetime. Depending on the species, a dolphin may only have between 4 and 240 teeth. This is because most of these animals swallow their prey whole, so they do not need lots of sharp teeth.
Photos above compare Dolphin teeth vs Sharks teeth.
Dolphins are carnivores that live in groups called “schools” or “pods”, numbering anywhere from 30 to 1000 dolphins! These pods often are grouped according to gender and age. Different species of delphinids prefer specific types of marine prey for their meals, though most eat squid, fish, crustaceans, and other marine mammals. They will often use a group feeding method whereby they surround a school of fish, pushing them into a small area, then one-by-one, the dolphins rush to the centre, devouring all the fish they can. Another method for feeding is to chase the fish into shallow water, or even onto shorelines, where they can feed more easily.
School of Pacific white-sided dolphins in Queen Charlotte Sound off Vancouver Island by of Rolf HickerBeing social animals, dolphins do create lasting bonds with one another, staying and taking care of injured or sick friends, and making sure they get to the water surface to breathe. Most dolphin species, due to the shape of their snout, often appear to be smiling. Sorry to say, but they aren’t. It is not that they aren’t feeling happy, it’s because their heads are shaped so they can glide more easily through the water, which leaves a permanent upturned mouth. As well, they have no facial muscles to express any possible feelings, happy or sad!
The small eyes, on either side of a dolphin’s head, see very well, both in and out of the water, though they do have difficulty in differentiating colours. This animal lacks olfactory lobes, so has no sense of smell and limited sense of taste. I guess those senses would be wasted on a dolphin since it swallows its food whole! Its auditory perception is amazing, being able to pick up higher frequency sounds that humans aren’t able to hear, to a distance of up to 12 miles away. What is most fascinating is that the sounds a dolphins hears, begin first by going into its mouth, then travelling through a fat-filled chamber to the inner ear!
A dolphin is capable of communicating with others using a series of clicking, chirping, and whistling sounds. It is able to make these noises because it has nasal air sacs near its blowhole. Scientists believe that each animal has its own distinct whistle that identifies itself when meeting others of its species. The clicking noises that a dolphin makes help it to find its prey. Like bats, they use echolocation, sending out repetitive clicking sounds from an organ in their head that is called a melon. Mmmm, that must be where we get the slang term for human heads!
Two Striped dolphins porpoising by OceanCareDolphins are often seen swimming out of the water, leaping high in the air and diving back in. This activity is called “porpoising”. They do this frequently when travelling from one area to another because moving through the air is much easier than going through water, so it saves energy. They will also porpoise as a means of communication, for fun, during fights, and to get rid of parasites.
It is generally believed that dolphins are very intelligent, having brains that not only learn well, but also understand and experience many emotions. Scientists studying the brains of delphinids have found that they contain the same neurons that humans have that are responsible for social conduct and self-awareness. Studies have observed dolphins demonstrating grieving rituals for others of their species. These animals are also believed to be capable of feeling depressed. The same behavioural markers for humans can be used for animals – lethargy, moodiness, sleeplessness, uncharacteristic aggressiveness, and helplessness. Interestingly, when animals that were believed to be depressed were given an antidepressant such as Prozac, it was found to be effective in alleviating the depression symptoms. Dolphins that have been captured, taken from their social groups to be trained for human entertainment, have exhibited behaviours linked to depression.
Some species of delphinids that are seen in Canadian waters include the Pacific white-sided and Atlantic white-sided dolphins, in the northern regions of their specific oceans. There are minor differences between these two species, though overall, they are very similar. Generally, they are 6-9 feet long and weigh in the range of 300-500 pounds, with the Atlantic dolphin the larger of the two. They are mostly a smooth glossy black, with grey on their sides, and a white belly. Their strong bodies are tapered, with dorsal fins that are tall and curved, and noses that are short. Lifespan for the Pacific species is up to 40 years, while the Atlantic dolphin lives to around 27 years. They feed on squid, shrimp, and small fish such as herring, cod, and sardines, swallowing them whole. Females start breeding between 6-12 years old, having babies once every 3 years, nursing the calves for 18 months.
Photos above are of the Pacific and Atlantic white-sided dolphins.
The species with the fewest teeth is the Risso’s dolphin which is found around Newfoundland. Interestingly, it only has blunt teeth in its lower jaw, between 4 and 14 of them. This delphinidae looks quite cute with a round head and no snout. Its body resembles a roadmap with visible scars all over its grey and white body. Calves are about 4-5 feet long at birth and weigh around 45 pounds. They are born almost black, and as they age, their skin lightens, just like humans who gradually turn grey over the years!
The lifespan of a Risso’s is 35 years. It can grow to up to 13 feet in length, weighing upwards of 1100 pounds. This dolphin is often found in deep water, being able to dive down to 1000 feet, holding its breath for 30”. It searches for prey mainly at night, at water surface, and their diet comprises mostly of squid, though it also eats krill, cuttlefish, octopus, and assorted fish.
Photos above are of the Risso’s dolphin including a close-up photo of a Risso’s dolphin head.
The warmer waters of Prince Edward Island play host to the Striped dolphin. These mammals can often be observed swimming at the water surface, and jumping up to 20 feet in the air! This species is similar in appearance to the Bottlenose dolphin of which Flipper belonged. They are often trained for entertaining humans at aquariums due to their athletic abilities, and they bring in a high profit for these companies.
Photos above are of the Striped dolphin.
Other delphinids that enjoy our Canadian waters include the White-beaked dolphin which swims near Newfoundland, the Short-beaked common dolphin around Nova Scotia, and the Northern right whale from out west, off the coast of British Columbia.
Photos above are of the White-beaked dolphin and the Short-beaked common dolphin.
Photos of Rare Right Whale surfacing off Anacapa Island, Channel Islands, California in May 5 2017 by Mark Hoffman
Last, but not least, is the Killer whale! Despite having the word “whale” in its name, it is actually a type of dolphin. Its range is all over the world, and in Canadian waters, is on both coasts, even up around Baffin Island and the northern part of Hudson Bay. Also referred to as an Orca, since that is the name of its species, it is the largest of the dolphin family. How big? The largest recorded was 32 feet long, weighing 22 000 pounds – the size of a school bus! But this fella isn’t yellow, it is black on top with a white underbelly.
Orcas are very smart and curious, and do not prey on humans! They do enjoy eating salmon, as well as squid and other marine mammals. There is no documentation of them killing a human in the wild. Now, in captivity, that’s a different story. Message – don’t capture them, leave them alone! They are very social animals, with male calves staying with their mothers for life. Daughters will go off for a period of time to have their own families. Average lifespan of females is 50 years, though some have lived up to 90 years, with males living a shorter time.
Photos above are of the Orca (Killer whale). The 1st photo is of an Orca newborn calf swimming.
The biggest threats to dolphins are entanglement in fishing lines and nets, over-hunting, damaging ocean noises, food shortages, and environmental contamination through garbage, oil and gas development, wastewater from industries, and urban runoff. This is an issue not just for them, but for all marine animals that the dolphins prey upon.
Some countries are aware that certain species of dolphin are diminishing in numbers, so are trying to find ways to stop this decline. Strategies include setting up regulations to protect the animals, building up their food stocks, and creating protective habitats for them. Due to dolphins being aquatic animals with habitats that include vast amounts of open water, it is difficult to research and protect them from all threats. Although North America has Protection Acts, other countries can come to within 200 miles of our shores to hunt marine animals and use the oceans for their own purposes. Keeping the Earth’s water animals at healthy numbers needs to be a worldwide undertaking.
So this April 14th, celebrate National Dolphin Day by remembering to take care of our oceans and respect the free life of these incredible Delphinids!
Editor’s Note:
The photos below show another interesting mammal of the sea, the Humpback Whale. The last picture of the Humpback whale tail diving has an interesting story. Besides the barnacles, the markings on the underside of the tail are from an attack by Orca whales. These markings on the left side are the perfect mouth/teeth marks from an attempt to take this giant down. Photos, courtesy of Jennifer Howard, were taken off Newfoundland.
