Creature Feature!

 Cetaceans (Dolphins, Whales & Porpoises)
Pinnipeds and Others (Seals, Sea Lions, Walruses and the Sea Otter)
Reptiles - The Sea Turtles
Fish
Invertebrates
Birds

Whales, Dolphins and Porpoises!

• Whales!
• Dolphins!
• Porpoises!
• Orcas!

Dolphins, whales and porpoises belong to the order Cetacea which means any hairless "fishlike" aquatic mammals that do not have external hind limbs, but have forelimbs shaped like a paddle. These animals are therefore called Cetaceans.

What are the differences between dolphins, whales and porpoises?

Dolphins have a well defined snout that is shaped like a beak and they have pointed teeth. Porpoises on the other hand have a blunt snout, teeth that are shaped like a chisel and shorter, fatter body. Whales have the largest bodies in this group and they may or may not have teeth. Whales with teeth are known as "Toothed Whales". All other whales are known as "Baleen Whales", which refers to the structure that they use for feeding instead of teeth. Will will look at Baleen and what it does a little later.

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Dolphins!

Dolphins are Marine mammals that are closely related to whales and porpoises. There are approximately 32 species of dolphins that exist in the world today. The most common example of a dolphin is the bottlenose dolphin, Tursiops truncatus which is a gray coloured dolphin that is often seen performing at aquariums. Orca's or Killer whales (Orcinus orca) are also in the dolphin family, although the word whale is in their name. Orca's are the largest species of dolphin growing up to 9 metres in length and weighing up to 9 tons. There are a few species of dolphin that live in freshwater. River dolphins, as they are called do not live in Canada, they are found in both Asia and South America.

Diet & Feeding Behavior

Dolphins eat about one third of their weight of food per day. Their diet consists of fish and squid. Their pointed beak and teeth help them grasp food quickly and skillfully.

Dolphins have between 200 to 250 sharp pointed teeth. When feeding they follow groups of fish called schools in groups of varying size.

Intelligence

Dolphins communicate with each other by making clicking and whistling sounds. The clicks are short bursts that contain approximately 300 sounds per second. Clicks are transmitted from an area located immediately below the blowhole. These clicks are helpful for the Echolocation of objects by the melon area of the head, which is located above the forehead and acts like an acoustic lens. The echoes received at an area of the rear of the lower jaw are transmitted by a fat organ in the lower jaw to the dolphins middle ear. This echolocation system is similar to that used by bats. Echolocation allows dolphins to navigate among members of their group, predators, larger objects and to detect fish, squid, and even small shrimp. The whistling sounds that dolphins produce are squeals that come from deep in the larynx. They are used to communicate emotions such as alarm, sexual excitement, and other emotional states.

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Did You Know?... Some scientists have suggested that dolphins may be capable of learning a true language and communicating with humans. Most scientists however, agree that dolphins have about the same intelligence as primates and that their is no evidence to support the claim that a dolphin communications approaches the complexity of a language as we know it.

Locomotion

Dolphins have a very powerful tail fin which is known as the Flukes (referring to the forked nature of the tail). This fin allows the dolphin to move forward. The tail flukes also provide dolphins with good power for swimming and jumping out of the water. The flippers on their sides are used for stabilization. Dolphins can swim up to 30 km/h, which is made easy by the shape of their bodies. Dolphins have a very Streamlined body which is shaped like a torpedo. This shape reduces the degree of resistance from the water passing over the dolphins body as it swims. Dolphins are expert divers as well and they can reach depths of more than 300 metres during a single dive.

How long do dolphins live?

The most commonly seen dolphin, the bottlenose dolphin is able to start having young between the ages of 5 and 13 years old. Mating occurs in the springtime and it takes 11 or 12 months for the calf to be born. Once the calf is born it swims to the surface for its first breath of air. Different species of dolphins have varying life expectancies. The bottlenose, common and river dolphins live to be approximately 20 years and most narwhals lives to be 25 years. Some narwhals and the spotted dolphin can live up to 50 years old, while Baird's beaked whale (also a member of the dolphin family) can live to be 70 years of age.

Respiration & Breathing

Blowhole

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Dolphins breathe by taking air in through the blowhole on the top of the head. This allows them to dive under water for up to 20 minutes before having to come to the surface of the water for more air. The air travels to the lungs after entering the blowhole, which immediately closes so that water does not get into the lungs.

Scientific Classification: Dolphins belong to the suborder Odontoceti of the order Cetacea. The bottlenose dolphin is classified as Tursiops truncatus and the common dolphin as Delphinus delphis. Pilot whales make up the genus Globicephala and the Pacific white-sided dolphin is classified as Lagenorhynchus obliquidens.

Don't Be Confused: A dolphinfish is actually a tropical fish (not a mammal) which gets to be a size of one or one and a half metres long !!

Lets examine the largest member of the dolphin family more closely . . . .

Orca's - Killer Whales!

The Orca or Killer Whale is the largest member of the dolphin family. Killer whales occur in more parts of the world than any other cetacean (see above). They occur in all oceans, both in open waters and close to shore. These dolphins are more common in the colder, more productive waters of both hemispheres than they are in tropical regions. Resident Populations can cover an area of several hundred square kilometers. The transient populations usually move through an area quickly, swimming more than 1000 km (more than 600 miles) of shoreline in a few days.

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Killer whales are black or deep brown for the mostpart. They have white patches above the eye, from the lower jaw to the stomach and a grayish-white saddle patch just behind the dorsal fin. Male orcas are much larger than the females. Mature females reach lengths of up to 8.5 m (up to 28 ft), and mature males reach lengths of up to 9.8 m (up to 32 ft). All killer whales have a large obvious dorsal fin which is triangular in shape in the middle of the back. The dorsal fin of males is much larger and taller than those of females. It may grow to 1.8 m (5.9 ft) tall on an adult male. The flippers of both sexes of killer whale are large and oval, which is unlike those of any other toothed whale.

Killer whales may be solitary or they can live in groups of 2 to more than 50 individuals. They feed on fish, squid, marine birds, pinnipeds (sea lions and seals), and sometimes other cetaceans (dolphins and porpoises). Orcas usually work together during hunting, especially when feeding they have to catch large prey such as marine birds, seals, and porpoises.

Most killer whales have specialized feeding habits that fit with the area that they live in. In the Pacific Northwest of the United States and Canada, the resident populations feed mainly on salmon and other fish that live near to shore. The transient populations in this area feed mostly on harbor seals and porpoises.

Did You Know?... Killer whales have even been known to attack blue whales, the largest species on the earth.

Killer Whale Food

Like other dolphins, Killer whales use echolocation to sense their surroundings and search for prey.

Groups of killer whales (called PODS) are very stable. The males and females stay in the pod that they are born to for life. It is believed that mating occurs between members of different pods to prevent inbreeding and birth defects. The female gives birth to one calf after 16 or 17 months. The calf nurses for approximately 14 to 18 months.

Scientific Classification: The killer whale belongs to the family Delphinidae of the suborder Odontoceti, order Cetacea. It is classified as Orcinus orca.

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Porpoises!

The word porpoise refers to small whales-like mammals that are closely related to dolphins. Porpoises are generally smaller than dolphins and they have rounded cone-shaped heads. They lack the typical beak of a dolphin. The dorsal fin on a porpoises is triangular in shape unlike the hooked dorsal fin of a dolphins.

The most commonly known porpoise is the common, or harbour porpoise. It is also the porpoise with the widest range. This porpoise lives in the cool and cold waters of the northern hemisphere, especially near tidal estuaries and the inlets of large rivers. They grow to a length of 1.2 to 2 m (4 to 6.6 ft) long and are usually bluish-black in colour. Some porpoises are more whitish on their underside. Porpoises frequently travel in small schools. Mating occurs between June and September and the female gives birth after about 11 months to a calf that measures between 0.7 to 1 m (2.3 to 3.3 ft) long.

Other porpoises have a more restricted range. The Dall porpoise for example has distinctly white underbelly markings that rise high up the side. This porpoise lives in the cold waters of the North Pacific as far south as Japan.

Scientific Classification: Porpoises make up the family Phocoenidae of the order Cetacea. The common porpoise is classified as Phocoena phocoena and the Dall porpoise as Phocoenoides dalli.

Whales!

Whales are another interesting group of marine mammals worth examining. They are descendants of land dwelling ancestors (as are dolphins and porpoises). Nowadays they are very different from these ancestors that had four legs. Today there are two groups of whales: Baleen Whales and Toothed Whales.

The largest living animal is the blue whale, Balaenoptera musculus. It can measure between 24 and 27 metres in length and it can weighs up to 120 tons. The blue whale is 25 times as large as the largest living land animal, the African Elephant.

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Diet & Feeding

Baleen whales are so named because of their baleen plates (structures that replace teeth) that filter shrimp, krill and small fish from the water. Baleen whales accomplish this filtration through three interesting mechanisms.

The first feeding method is commonly used by Right Whales (Balaenidae). The prey of these whales concentrate at the surface of the water. The whale swims along the waters surface with its mouth wide open. Water and plankton pass along the sides of the tongue and the water comes back out through the baleen which traps the food organisms. This group of whales are characterized by long baleen and no ventral pleats.

The second filtering style is employed by Rorqual whales (Balaenopteridae) which have huge mouths and heads and shorter baleen. The most unique feature on these whales is a furrowed throat pouch. The many folds and pleats in the pouch allow the animal to swallow huge amounts of water at one time. Rorquals usually feed on dense swarms of krill (similar to shrimp) and fish. Food and water are gulped into the pouch, which is then contracted allowing the water to pass through the baleen trapping the food.

Did You Know?... The blue whale can engulf 6400 kilograms of water in one gulp.

The third method of filter feeding is carried out by the Gray Whale, Eschrichtius robustus. This whale feeds by scooping the matter from the sea floor into its mouth and filtering out the bottom-dwelling organisms with its baleen.

Toothed whales are part of the suborder Odontoceti along with dolphins and porpoises. This group also includes sperm whales, pilot whales, the beluga, the narwhal and others.

Did You Know?... The large whale that is in the novel Moby Dick is a Giant Sperm Whale.

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The Giant Sperm Whale, Physeter catodon can reach a maximum length of 18 metres and can weigh over 53 000 kilograms. Pigmy Sperm Whales, Kogia sp. are much smaller at 4 metres in length and weighing approximately 320 kilograms.

The Giant Sperm Whale has 25 teeth on each side of its lower jaw which it uses to clamp onto food. They dive up to 1130 meters in search of deep-sea squid. They also eat barracuda, sharks and skates.

Giant Sperm Whales are highly social whales, congregating in large groups of up to 1000 individuals. There are however some solitary males.

The Beluga Whale, Delphinapterus leuceus is known as the "White Whale". It's body shape is similar to that of a dolphin without a dorsal fin or a small pilot whale. The beluga is pure white and it lives in northern seas like the narwhal (below). In the summer the belugas move up large rivers where they feed mainly on fish on the bottom and at medium depths.

The Narwhal, Monodon monoceros is a unique creature. It is a small whale that looks a lot like the beluga whale, except for the large straight Tusk that comes out of its forehead. Narwhals live in northern oceans and they are mainly pelagic, living in open water areas. The male narwhals will fence each other with their tusks, which can break off or get stuck in one of the whales bodies. The tusk is actually a modified tooth and it is only present in males. It can reach a length of 2.7 metres.

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Did You Know?... Both narwhals and belugas are extremly vocal animals. The beluga is often called the "sea canary" because of the unique sounds that it makes.

Barnacles & Whales

Whales can be a habitat for other small animals. Barnacles for example encrust themselves on the whales body. The barnacles which filter feed particles of food from the water get the leftover particles from the whales food. Sea lice is another pest that likes to live on whales. Some scientists believe that when whales jump out of the water and land hard on their bodies they are trying to get rid of pests.

Migration

Whales must migrate large distances to the place where they breed in the summer. They move to avoid cold weather and to take advantage of increases of seasonal food supplies in certain areas. Some whales travel from the Arctic to their summer breeding grounds in the Indian Ocean.

The Gray Whale for example travels very long distances. The round trip distance of its migration can total between 10 000 and 22 000 kilometres.

Movement

Locomotion in whales is very similar to that of dolphins and porpoises. The tail flukes are used for power and the pectoral fins are used for balance. The following are different types of movements that whales, dolphins and porpoises do in their daily lives.

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Breaching is a behaviour where the animal jumps fully out of the water. Many whale, dolphin and porpoise species can be seen doing this in the wild. One theory about why these animals breach relates to parasites found on their bodies. It is thought that the whales force when it hits the water helps to break loose annoying parasites such as sea lice and barnacles.

Spy-hopping occurs when the cetacean uses the force of its tail to lift its head out of the water. Scientists believe that they do this to get a good look of their surroundings.

Lobtailing refers to flipper and fluke smacking. This is a possible form of communication between individuals or groups. The loud sounds produced travel great distances underwater. It is also believed that the smacking is done for fun.

Fluke waving helps to orientate the animal before diving. This is when the flipper or flukes stick up out of the water.

Fin whales can reach a maximum age of approximately 90 years. This age is measured by growth layers in a horny plug that is part of the internal structure of the ear. Sperm whales reach a maximum life expectancy of about 60 years. This is measured by the layers of dentine in the teeth.

Links

Beluga Whales - Sea World Education Department Resource
http://www.seaworld.org/infobooks/Beluga/home.html

Canadian Marine Mammals
http://www.aquatic.uoguelph.ca/mammals/whales/marine_frame.htm

Dall's Porpoise
http://www.aquatic.uoguelph.ca/mammals/whales/accounts/dall.htm

Dolphins
http://earthtrust.org/wlcurric/dolphins.html

Harbour Porpoise
http://www.imma.org/porpoise.html

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Killer Whales - EnchantedLearning.com
http://www.enchantedlearning.com/subjects/whales/species/Orca.shtml

Marine Mammals - The Natural History of Nova Scotia
http://museum.gov.ns.ca/mnh/nature/nhns/t11/t11-12.htm

Phocoena.org
http://www.phocoena.org/factsheets/index.html

WhaleNet
http://whale.wheelock.edu/Welcome.html

References!

Carwardine, Mark. 1995. Eyewitness Handbooks: Whales, Dolphins and Porpoises. Stoddart Publishing Co. Limited, Toronto.

Donoghue, Michael & Wheeler, Annie. 1990. Save the Dolphins. Key Porter Books Limited, Toronto. 119pp.

Gambell, Ray. 1989. Whales: How they live. Mallard Press, New York. 46pp.

Microsoft Encarta. 1996 Edition. Microsoft Corporation

Microsoft Oceans.1995 Edition. Microsoft Corporation.

National Audubon Society Pocket Guide: Familiar Marine Mammals of North America. 1997.

New Webster's Dictionary and Thesaurus. 1992. Lexicon Publications, Inc., Danbury, CT

Vaughan, Terry A. 1986. Mammalogy. Saunders College Publishing, Toronto. 576pp.

Artwork:
Clipart by the Corel Corporation
Original Art by Jennifer Lalonde