AY Honor Cetaceans Answer Key
Skill Level
2
Year
2001
Version
22.12.2024
Approval authority
General Conference
1
The Cetacean family is different from most other sea life because Cetaceans are mammals.
This means :
- A: They give birth to live babies. The largest whale is the Blue Whale and its newborn baby will be up to 7 meters long and weigh up to 2700 kg/6,000 lbs, (about as much as two cars).
- The large whale mothers move to warm tropical waters to give birth and spend about six months there so their babies can grow a layer of fat (blubber) to help them survive the cold frigid waters where they live for the other six months. While in the warm waters the adult whales do not eat at all.
- B: They feed their babies milk. The baby will drink 400 liters / 100 gallons of milk and gain 90 kg / 200 lbs a day for the first seven months of its life.
- C: They have warm blood. A blue whale’s heart is the size of a small car and its aorta (the main heart artery) is the diameter of a soccer ball.
- D: They breathe air just like us. This means that they must hold their breath while under the water. A Sperm Whale can hold its breath for 30 minutes. When they want to breathe they come to the surface, blow out moist air from their lungs and snatch a new breath. Their nostrils are called blowholes. Baleen whales have two blowholes and toothed whales one blowhole. The whale hunters could tell what sort of whale it was by the shape of the spout blown out.
- E: They have some hair on their bodies. You may not easily see the hair on a whale but most have small whiskers on the chin.
In addition to the characteristics of mammals listed above, cetaceans differ from other sea life in other ways as well. One of these differences between a cetacean and a fish is the shape of the tail. The tail of a fish is vertical and moves from side to side when the fish swims. The tail of a cetacean – called a "fluke" – is horizontal and moves up and down.
2
The order Cetacea contains about 90 species, all marine except for four species of freshwater dolphins. The order contains two suborders: Mysticeti (baleen whales) and Odontoceti (toothed whales, which includes dolphins and porpoises). The species range in size from Commerson's dolphin, smaller than a human, to the blue whale, the largest animal ever known to have lived.
Baleen Whales
The baleen whales, also called whalebone whales or great whales, are one of two suborders of the Cetacea (whales, dolphins and porpoises). Baleen whales, rather than having teeth, have baleen plates which hang from the upper jaw and are used for filtering food from water. This distinguishes them from the toothed whales. Baleen is a type of hair but stiff like a soft fingernail. It grows from the roof of the mouth in two rows and is used to filter out food from water.
The whale is able to take in a huge mouthful of water and then squeeze its mouth shut and squeeze out the water while straining out the food. Baleen whales feed on tiny creatures called krill and need lots of these to fuel their bodies. Most of the big whales are baleen whales, e.g. Blue whale, humpback whale and fin whale. Krill is one of their major foods, which they strain through their baleen.
Baleen whales are generally larger than toothed whales, and females are larger than males. This group includes the Blue Whale, the largest animal species that has ever lived. Baleen whales have two blowholes, causing a V-shaped blow whereas toothed whales have a single blowhole.
Toothed Whales
The toothed whales have teeth because they feed on creatures much larger than krill, such as squid, fish, seals and even other whales. These whales are the dolphins and porpoises, the killer whale and the giant sperm whale.
Dolphins and porpoises mainly feed on fish and may hunt in groups called pods.
Killer whales eat seals, fish, dolphins and even blue whales. They are called the Wolves of the Sea.
The sperm whale is the largest toothed whale. It will eat fish and octopus but its favorite food is giant squid that live in the deep ocean. A sperm whale has been known to dive to 3200 meters looking for squid.
| Characteristic | Odontoceti (toothed whale) |
Mysticeti (baleen whales) |
| Feeding | Echolocation, fast | Filter feeder, not fast |
| Size | Smaller (except Sperm whale and beaked whale) | Larger (except pygmy right whale) |
| Blowhole | One | Two |
| Dentition | Teeth | Baleen plates |
| Melon | Ovoid, in anterior facial region | Vestigial or none |
| Skull and facial tissue | Dorsally asymmetric | Symmetric |
| Sexual dimorphism | Some species have larger males | Females always larger |
| Mandible | Symphyseal (fused anteriorly) | Nonsymphyseal |
| Pan bone of lower jaw | Yes | No |
| Maxillae projection | Outward over expanded supraorbital processes | Under eye orbit, with bony protuberance anterior to eye orbit |
| Olfactory nerve and Olfactory bulb | Absent& | Vestigial& |
| Periotic bone | tympanic bulla | Fused with skull& |
3
In some cultures, whales provide meat for both pets and for humans. Whales also provide oil for fuel, perfumes, and other products. Entire communities were established devoted to whaling. Although whaling is now illegal in most parts of the world, whales continue to provide benefits to man. They are a major tourist attraction in areas where they are common, and an entire industry has sprung up to bring people to see the whales.
There are many stories of dolphins protecting shipwrecked sailors against sharks by swimming circles around the swimmers. Because of their high capacity for learning, dolphins have been employed by humans for any number of purposes. Dolphins trained to perform in front of an audience have become a favorite attraction at many aquariums, for example SeaWorld. Such places may sometimes also provide an opportunity for humans to interact very closely with Dolphins. Dolphin/Human interaction is also employed in a curative sense at places where dolphins work with autistic or otherwise disabled children. The military has employed dolphins for various purposes from finding mines to rescuing lost or trapped persons.
4
Whales have a very thick layer of fat beneath their skin called blubber. Blubber is a very effective insulator, much like a wet suit which is used for keeping divers warm when they swim in cold waters. Blubber is far more effective than a wet suit because it is so thick. In fact, blubber can comprise up to 50% of the body mass of some cetaceans during some points in their lives. Blubber also serves as a source of energy, and whales metabolize (burn) fat to generate heat internally and thus warm themselves. People metabolize fat too when they shiver (shivering serves the same purpose - to warm us up).
5
5a
Quizlet flashcards (4 cards): Link
So God created the great creatures of the sea and every living and moving thing with which the water teems, according to their kinds, and every winged bird according to its kind. And God saw that it was good.
5b
- Son of man, take up a lament concerning Pharaoh king of Egypt and say to him:
- " 'You are like a lion among the nations;
- you are like a monster in the seas
- thrashing about in your streams,
- churning the water with your feet
- and muddying the streams.
5c
- Am I the sea, or the monster of the deep,
- that you put me under guard?
5d
- For as Jonah was three days and three nights in the belly of a huge fish, so the Son of Man will be three days and three nights in the heart of the earth.
6
Go beyond just the part about Jonah and the Whale everyone knows. There is a whole (short) Bible book on Jonah.
If you are teaching this honor to your unit, you can have them retell the story (and act it out) for worship at a campout or at a regular meeting. You can also have your Pathfinders tell the story during regular church service if your church has a time allotted for "Children's Story". Alternately, you can have them write it out and read it back to you (or to the group).
7
7a
These are the "strainers" in a baleen whale's mouth.
7b
A cetacean breaths through this little hole in the top of its head.
7c
The fin on the top of many cetaceans.
7d
These are hard to see because they're so small, but cetaceans all have them on the sides of their heads.
7e
The better to see you with!
7f
These are the folds in a baleen whale's throat and allow the whale's throat to expand when it fills its mouth with water to filter its food through its baleen.
7g
The tail.
7h
The fins on the side.
7i
The reproductive organ of a female cetacean.
7j
The notch in the middle of the trailing edge of the fluke.
7k
The part of the body to which the fluke is attached.
8
The order Cetacea includes whales, dolphins, and porpoises. There are around 90 living species, divided into the suborders Mysticeti (the baleen whales covering about 17 species) and Odontoceti (the toothed whales, including porpoises and dolphins covering about 73 species). All Cetacea live in ocean water except for the river dolphins. We present at least one sample from each family of Cetacea here to help you learn to identify them. For more details including range maps and comparative sizes visit https://en.wikipedia.org/wiki/List_of_cetaceans or the wikipedia article linked from the scientific name.
Quizlet Flashcards (40+ options): Link
Baleen whales
- Family Balaenidae: right whales
Balaenoptera musculus
The blue whale (Balaenoptera musculus)
Where found: Blue whales were abundant in nearly all the oceans on Earth until the beginning of the twentieth century. For over a century, they were hunted almost to extinction by whalers until protected by the international community in 1966. A 2002 report estimated there were 5,000 to 12,000 blue whales worldwide located in at least five groups. Before whaling, the largest population was in the Antarctic, numbering approximately 239,000 (range 202,000 to 311,000). There remain only much smaller (around 2,000) concentrations in each of the eastern North Pacific, Antarctic, and Indian Ocean groups. There are two more groups in the North Atlantic, and at least two in the Southern Hemisphere.
Description:
At 30 metres (98 ft) in length and 170 tonnes (190 short tons) or more in weight, the Blue Whale is the largest known animal ever to have existed.
Long and slender, the blue whale's body can be various shades of bluish-grey dorsally and somewhat lighter underneath. There are at least three distinct subspecies: B. m. musculus of the North Atlantic and North Pacific, B. m. intermedia of the Southern Ocean and B. m. brevicauda (also known as the pygmy blue whale) found in the Indian Ocean and South Pacific Ocean. B. m. indica, found in the Indian Ocean, may be another subspecies. As with other baleen whales, its diet consists almost exclusively of small crustaceans known as krill.- Family Balaenopteridae: rorquals
Megaptera novaeangliae
Humpback Whale (Megaptera novaeangliae)
Where found: The Humpback Whale lives in oceans and seas around the world, and is regularly sought out by whale-watchers.
Description: The Humpback is a very large whale. It is well known for its breaching (leaping out of the water), its unusually long front fins, and its complex whale song. The species feeds only in summer and lives off fat reserves during winter. It is an energetic feeder, taking krill and small schooling fish, such as herring, capelin and sand lance. It will hunt fish by direct attack or by stunning them by hitting the water with its flippers or flukes. Its most inventive feeding technique is called bubble net fishing. A group of whales will blow bubbles while swimming to create a visual barrier against fish, while one or more whales in the group make vocalizations that drive the fish against the wall. The bubble wall is then closed, encircling the fish, which are confined in an ever-tighter area. The whales then suddenly swim upwards and through the bubble net, mouths agape, swallowing thousands of fish in one gulp. This technique can involve a ring of bubbles up to 30 m (100 ft) in diameter and the cooperation of a dozen animals at once. It is one of the more spectacular acts of collaboration and cooperation among marine mammals.
- Family Eschrichtiidae: gray whale - The only species in its family.
Eschrichtius robustus
Grey Whale (Eschrichtius robustus)
Where found: Two Pacific Ocean populations of Gray Whales exist: one small population traveling between the Sea of Okhotsk and southern Korea, and a larger one traveling between the waters off Alaska and the Baja California. A third, North Atlantic, population was hunted to extinction 300 years ago. In the fall, the California Gray Whale starts a 2–3 month, 8,000–11,000 km trip south along the west coast of the United States and Mexico. The animals travel in small groups. The destinations of the whales are the coastal waters of Baja California and the southern Gulf of California, where they breed and the young are born.
Description:
- Family Neobalaenidae: pygmy right whale - only one species in its family.
Caperea marginata
Pygmy right whale (Caperea marginata)
Where found: Southern Ocean
Description: The Pygmy right whale is rarely seen and little studied. Only about 25 "at sea" sightings have been recorded. It is not a right whale (misnamed) and was thought extinct until 2012. The smallest of the baleen whales, ranging between 6 metres (20 ft) and 6.5 metres (21 ft) in length and 3,000 and 3,500 kg in mass. Despite its name, the pygmy right whale may have more in common with the gray whale and rorquals than the bowhead and right whales.
Toothed whales
Toothed whales include both true whales, porposes, and ocean and river dwelling dolphins. The Toothed Whales make up about 73 out of the 90 known living species of Cetaceans. As the name implies, these species have teeth to hunt prey with.
Family Monodontidae: Narwhal and Beluga
These two related species live in cold Arctic waters.
Delphinapterus leucas
Beluga Whale (Delphinapterus leucas)
Where found: Arctic and sub-arctic oceans around North America, Russia and Greenland.
Description: Adapted to life in the Arctic, it has a number of anatomical and physiological characteristics that differentiate it from other cetaceans. The unmistakable all-white colour, absence of a dorsal fin, and the distinctive protuberance at the front of its head which houses an echolocation organ called the melon. The beluga’s body size is between that of a dolphin’s and a true whale’s, with males growing up to 5.5 m (18 ft) long and weighing up to 1,600 kg (3,500 lb). This whale has a stocky body; it has the greatest percentage of blubber. Its sense of hearing is highly developed and it possesses echolocation, which allows it to move about and find blowholes under sheet ice. Belugas form groups of up to 10 animals on average, although during the summer months, they can gather in the hundreds or even thousands in estuaries and shallow coastal areas. They are slow swimmers, but they can dive down to 700 m (2,300 ft) below the surface. They are opportunistic feeders and their diets vary according to their locations and the season. They mainly eat fish, crustaceans and other deep-sea invertebrates. Worldwide population is thought be around 150,000 individuals. They are migratory and the majority of groups spend the winter around the arctic ice cap; but when the sea ice melts in summer, they move to warmer river estuaries and coastal areas. Belugas are one of the cetaceans most commonly kept in captivity in aquaria and wildlife parks in North America, Europe and Asia where they are popular with the public due to their colour and expressivity. Wilma the Beluga Whale
Monodon monoceros
Narwhal (Monodon monoceros)
Where found: Arctic and sub-arctic oceans around North America, Russia and Greenland.
Description: Adapted to life in the Arctic, Narwhale Nat Geo. These small whales have a long tusk (actually an elongated left canine tooth) protruding from the mouth. They eat fish which they hunt beneath the pack ice of arctic waters. Thy do not have a dorsal fin as most whales and dolphins do. Narwhals range from 4 to 5.5 meters (13-18 feet) in length.
Family Physeteridae: Sperm Whales
There are three species in the sperm whale family, including the largest toothed predator in the world and smallest whale in the world. A common characteristic of these species is the spermaceti, a semi-liquid waxy white substance filling the 'case' or spermaceti organ in the whale's head, which is thought to be involved in providing ballast for diving and maintaining buoyancy. This may be done by flushing cold water through the nose, hardening the spermaceti, to dive, and pumping warm blood to melt the spermaceti to surface. All three species dive to great depths to find food, although the sperm whale is believed to dive much deeper than either of its smaller cousins. Sperm whales eat squid, fish, and even sharks.
Physeter macrocephalus
Sperm Whale (Physeter macrocephalus)
Where found: The sperm whale can be found anywhere in the open ocean.
Description: Largest of the toothed whales and largest toothed predator in the world. The Sperm Whale breaks all kinds of records! Mature males may reach 20.5 metres (67 ft) and 57,000 kilograms (males much larger than females). It is the loudest of any animal, second deepest diving mammal with dives of up to 90 minutes, largest brain (five times heavier than a human brain), 116 kg (255 lbs) heart, longest intestinal system (exceeding 300 m in larger specimens) and other mind blowing measurements. The sperm whale's distinctive shape comes from its very large, block-shaped head, which can be one-quarter to one-third of the animal's length. The S-shaped blowhole is located very close to the front of the head and shifted to the whale's left, giving a distinctive bushy, forward-angled spray. Primary food is squid and they can live for more than 60 years. The sperm whale's flukes are triangular and very thick. Proportionally, they are larger than that of any other cetacean, and are very flexible. The whale lifts its flukes high out of the water as it begins a feeding dive. It has a series of ridges on the back's caudal third instead of a dorsal fin. The largest ridge was called the 'hump', and can be mistaken for a dorsal fin because of its shape and size. In contrast to the smooth skin of most large whales, its back skin is usually wrinkly and has been likened to a prune by whale-watching enthusiasts. From the early 18th century through the late 20th the species was a prime target of whalers. The head of the whale contains a liquid wax called spermaceti, which was used in lubricants, oil lamps, and candles. Ambergris, a waste product from its digestive system, is still used as a fixative in perfumes. The Sperm Whale is now protected by a whaling moratorium, and is currently listed as vulnerable. Sperm whales have sunk ships, including the real life Moby Dick who sunk the Essex. Jonathan Bird's Blue World: Sperm Whales
Kogia breviceps
Pygmy & Dwarf Sperm Whales (Kogia breviceps)
Where found: Dwarf and Pygmy sperm whales are found throughout the tropical and temperate waters of the Atlantic, Pacific and Indian Oceans. However, they are rarely sighted at sea, so most data come from stranded and captured animals - making a precise range and migration map difficult. The dwarf is more coastal than the pygmy. There is no accurate estimate of number of these whales in the world or good data on conservation status.
Description: The dwarf sperm whale is the smallest species commonly known as a whale. It grows up to 2.7 m (8.9 ft) in length and 250 kilograms (550 lb) in weight. The species makes slow, deliberate movements with little splash or blow and usually lies motionless when at the sea's surface. Consequently it is usually observed only in very calm seas. These two species were not distinguished from each other until 1966 and are difficult to tell apart but the dwarf is slightly smaller and has a larger dorsal fin than the pygmy. The body is mainly bluish gray with a lighter underside with slightly yellow vein-like streaks possibly visible. There is a white false gill behind each eye. The flippers are very short and broad. The top of the snout overhangs the lower jaw, which is small. The whales have long, curved and sharp teeth (0–6 in the upper jaw, between 14 and 26 in the lower). These whales expel a dark reddish substance when frightened or attacked—possibly to put off any predators. They are usually solitary or paired but have occasionally been seen in small groups. All sperm whales have a spermaceti organ in the forehead. The brain of the dwarf sperm whale is roughly half a kilogram in mass.Video of stranded Pygmy Sperm Whale
Family Ziphiidae: Beaked Whales
There are 22 recognized species of Beaked Whales, toothed whales notable for their elongated beaks. Of air breathing animals, beaked whales are some of the most extreme divers. Cuvier's beaked whales regularly dive for an hour at a depth over 1,000 m (3,300 ft), and the longest and deepest foraging dive recorded is 137.5 minutes and 2,992 m (9,816 ft).
Beaked whales are one of the least known groups of mammals because of their deep-sea habitat, mysterious habits, and apparent low abundance. Only three to four of the 22 species are reasonably well-known. Baird’s and Cuvier's beaked whales were subject to commercial exploitation, off the coast of Japan, while the Northern bottlenose whale was extensively hunted in the northern part of the North Atlantic late in the 19th and early in the 20th centuries.
Berardius
Giant Beaked Whale/Arnoux and Baird’s Beaked Whales (Berardius)
Where found: Arnoux’s beaked whale Berardius arnuxii lives in cold Southern Hemisphere waters and Baird’s beaked whale Berardius bairdii is found the cold temperate waters of the North Pacific.
Description: You would not be able to see the differences between Arnoux and Baird’s beaked whales except that they live on opposite ends of the world. They grow to 10–12 m in length and up to 14,000 kg (31,000 lb). They have very long prominent beak, even by beaked whale standards. The lower jaw is longer than the upper and the front teeth are visible even when the mouth is fully closed. The melon is particularly bulbous. The body shape is slender - the girth is only 50% of length. The body is uniformly coloured and a particular individual's colour may be anything from light grey through to black. The flippers are small, rounded and set towards the front of the body. The dorsal fin similarly is small and rounded and set about three-quarters of the way along the back. Adult males and females of both species pick up numerous white linear scars all over the body as they age and may be a rough indicator of age.
- B. arnuxii is known as Arnoux's beaked whale, southern four-toothed whale, southern beaked whale, New Zealand beaked whale, southern giant bottlenose whale, and southern porpoise whale.
- B. bairdii is known as Baird's beaked whale, northern giant bottlenose whale, North Pacific bottlenose whale, giant four-toothed whale, northern four-toothed whale, and North Pacific four-toothed whale.
Hyperoodon
Northern and Southern Bottlenose Whales (Hyperoodon)
Where found: Northern bottlenose whale are found in the North Atlantic Ocean and is found in cool and subarctic deep waters such as the Davis Strait, the Labrador Sea, the Greenland Sea and the Barents Sea and as far south as Cape Verde Islands. Southern bottlenose whales are probably the most abundant whale in Antarctic waters.
Description: These sister species are fairly rotund with an extremely bluff melon. The beak is long and white on males but grey on females. The dorsal fin is relatively small at 30–38 centimetres (12–15 in) and set behind the middle of the back. It is falcate (sickle-shaped) and usually pointed. The Northern species measures 9.8 metres (32 ft) in length when physically mature. The back is mid-to-dark grey, with a lighter underside. The Southern bottlenose whale smaller growing to 7.5 m (25 ft) in length when physically mature. The back is light-to-mid grey, also with a lighter underside. Males are about 25% larger than females. These bottlenose whales live up to 37 years. Weight estimates are hard to come by. For the northern bottlenose whale, 5,800–7,500 kilograms (12,800–16,500 lb) is given somewhat consistently, while the smaller and less studied southern species will be lighter. The bottlenose whales are some of the deepest diving mammals known, reaching depths of 1453 m (4767 ft) The whales feed on squid, sea cucumbers, herring, cuttlefish, sea stars and other benthic invertebrates.Video Northern Bottlenose Whale
Ziphius cavirostris
Cuvier's beaked whale (Ziphius cavirostris)
Where found: Open ocean worldwide except in the Arctic and Southern oceans.
Description: The Cuvier's beaked whale or goose-beaked whale is the most widely distributed of all the beaked whales. Individuals commonly have white scars and patches caused by cookiecutter sharks. It prefers depth greater than 1,000 m (3,300 ft) and avoids ships, it is still one of the most frequently spotted beaked whales. The maximum known depth reached by the Cuvier's beaked whale is 2,992 metres (9,816 ft), or 1.8 miles, making it the deepest-diving mammal. The species name comes from Greek xiphos, "sword", and Latin cavus, "hollow" and rostrum, "beak", referring to the indentation on the head in front of the blowhole. The body of Cuvier's beaked whale is robust and cigar-shaped, similar to those of other beaked whales and can be difficult to distinguish from many of the mesoplodont whales at sea. Males and females are the same size up to about 5–7 m (16–23 ft) in length 2,500 kg (5,500 lb). The dorsal fin is curved, small and located two-thirds of the body length behind the head. Flippers are equally small and narrow and can be tucked into pockets in the body wall, presumably to prevent drag while swimming. Like other beaked whales, its flukes are large and lack the medial notch found in all other cetaceans. The head is short with a small, poorly defined rostrum and a gently sloping melon. A pair of throat grooves allow the whale to expand this region when sucking in its prey. Cuvier's beaked whale has a short beak in comparison with other species in its family, with a slightly bulbous melon. The melon is white or creamy in color and a white strip runs back to the dorsal fin about two-thirds of the way along the back. The rest of the body color varies by individual: some are dark grey; others a reddish-brown. The dorsal fin varies in shape from triangular to highly falcate, whilst the fluke is about one-quarter the body length. They live for forty years. Culvers beaked whale
Family Phocoenidae: Porpoises
Porpoises are small cetaceans that are distinct from dolphins, although the word "porpoise" has been used to refer to any small dolphin, especially by sailors and fishermen. The most obvious visible difference between the two groups is porpoises have spatulate (flattened) teeth distinct from the conical teeth of dolphins. Porpoises rear more young more quickly than dolphins. They have small flippers, notched tail flukes, and no beaks. All carry at least 11 pairs of small teeth in their upper and lower jaws.
Porpoises, divided into six species, live in all oceans, mostly near the shore.
Neophocaena phocaenoides
Finless Porpoise (Neophocaena phocaenoides)
Where found: The Finless Porpoise lives in the coastal waters of Asia, especially around India, China, Indonesia and Japan. A unique fresh water population is found in the Yangtze River. At the western end, their range includes the length of the western coast of India and continues up into the Persian Gulf. Throughout their range, the porpoises stay in shallow waters (up to 50m), close to the shore, in waters with soft or sandy seabeds. In exceptional cases they have been encountered as far as 100 miles off-shore in the East China and Yellow Seas, albeit still in shallow water.
Description: The Finless Porpoise almost completely lacks a dorsal fin. Instead there is a low ridge covered in thick denticulated skin. Adult Finless porpoises are a uniform light grey color. Infants are mostly black with grey around the dorsal ridge area, becoming grey after 4-6 months.
Phocoena phocaena
Harbour Porpoise (Phocoena phocaena)
Where found: The Harbour Porpoise, as its name implies, stays close to coastal areas or river estuaries and as such is the most familiar porpoise to whale watchers. This porpoise often ventures up rivers and has been seen hundreds of miles from the sea.
Description: The Harbour Porpoise is a little smaller than the other porpoises. It is about 75 cm long at birth. Males grow up to 1.6 m and females to 1.7 m. The females are correspondingly heavier, with a maximum weight of around 76 kg compared with the males' 61 kg. The body is robust and the animal is at its maximum girth just in front of its triangular dorsal fin. The beak is poorly demarcated. The flippers, dorsal fin, tail fin and back are a dark grey. The sides are a slightly speckled lighter grey. The underside is much whiter, though there are usually grey stripes running along the throat from the underside of the mouth to the flippers.
Family Delphinidae: Oceanic Dolphins
Dolphins, including the river dolphins, comprise 45 species out of the 90 Cetacean species. Six species in the family Delphinidae are commonly called "whales", but genetically are dolphins. They are sometimes called blackfish. These are the Melon-headed whale, (Peponocephala electra) Killer whale/Orca (Orcinus orca). Pygmy killer whale, (Feresa attenuata), False killer whale, (Pseudorca crassidens), Long-finned pilot whale, (Globicephala melas) and the Short-finned pilot whale (Globicephala macrorhynchus)
Orcinus orca
Orca, or killer whale (Orcinus orca)
Where found: The orca is found in all the world's oceans, from the frigid Arctic and Antarctic regions to warm, tropical seas.
Description: The Orca or Killer Whale is the largest species of the oceanic dolphin family (Delphinidae). Orcas are versatile predators, with some populations feeding mostly on fish and others on other marine mammals, including large whales. Wild orcas are usually not considered a threat to humans.
Tursiops truncatus
Bottlenose dolphin (Tursiops truncatus)
Where found: The Bottlenose dolphin inhabits warm and temperate seas worldwide and may be found in all but the Arctic and the Antarctic Oceans.
Description: The Bottlenose Dolphin is the most common and well-known dolphin species. They are gray, varying from dark gray at the top near the dorsal fin to very light gray and almost white at the underside. This makes them harder to see both from above and below when swimming. The elongated upper and lower jaws form what is called the rostrum and give the animals their name of Bottlenose. The real nose however is the blowhole on top of the head, and the nasal septum is visible when the blowhole is open. Their face shows a characteristic "smile".
Delphinus delphis
Common dolphin (Delphinus delphis)
Where found: The common dolphin is widely distributed in temperate, sub-tropical and tropical waters throughout the world in a band roughly spanning 40 degrees south to 50 degrees north. The species typically prefer enclosed bodies of water such as the Red and Mediterranean Seas. Deep off-shore waters and to a lesser extent over continental shelves are preferred to shallow waters. Some populations may be present all year round, others appear to move in a migratory pattern. Preferred surface water temperature is 10-28 degrees Celsius.
Description: Common dolphins travel in groups of around 10-50 in number and frequently gather into schools numbering 100 to 2000 individuals. These schools are generally very active - groups often surface, jump and splash together. Typical behavior includes breaching, tail-slapping, chin-slapping, bow-riding and porpoising.
Superfamily Platanistoidea: River Dolphins (fresh water dwelling)
River Dolphins are part of the toothed whale group but are uniquely adapted to living in fresh water.
- Family Iniidae: river dolphins
Carcharhinus limbatu
Amazon River Dolphin or Pink Dolphin (Carcharhinus limbatu)
Where found: freshwaters of the Orinoco, Amazon and Araguaia/Tocantins River systems of Brazil, Peru, Bolivia, Ecuador, Colombia and Venezuela.
Description: Although not a large cetacean in general terms, this dolphin is the largest freshwater cetacean; it can grow larger than a human. Body length can range from 1.53 to 2.4 m (5.0 to 7.9 ft), depending on subspecies. Females are typically larger than males. The largest female Amazon river dolphins can range up to 2.5 m (8.2 ft) in length and weigh 98.5 kg (217 lb). The largest male dolphins can range up to 2.0 m (6.6 ft) in length and weigh 94 kg (207 lb). They have unfused neck vertebrae, enabling them to turn their heads 90 degrees. Their flexibility is important in navigating through the flooded forests. Also, they possess long beaks which contain 24 to 34 conical and molar-type teeth on each side of the jaws. In colour, these dolphins can be either light gray or carnation pink.
- Family Lipotidae: baiji
Lipotes vexillifer
Baiji (Lipotes vexillifer)
Where found: Yangtze River in China until extinction
Description: The Baiji (Chinese: 白鱀豚) was a freshwater dolphin found only in the Yangtze River in China. Lipotes meaning "left behind", vexillifer "flag bearer". The baiji population declined drastically in decades as China industrialized and made heavy use of the river for fishing, transportation, and hydroelectricity. Efforts were made to conserve the species, but a late 2006 expedition failed to find any baiji in the river. Organizers declared the baiji functionally extinct, which would make it the first known aquatic mammal species to become extinct since the demise of the Japanese sea lion and the Caribbean monk seal in the 1950s. It would also be the first recorded extinction of a well-studied cetacean species to be directly attributable to human influence. In August 2007, a Chinese man reportedly videotaped a large white animal swimming in the Yangtze. Although it was tentatively confirmed that the animal on the video is probably a baiji, the presence of only one or a few animals, particularly of advanced age, is not enough to save a functionally extinct species from true extinction. The last known living baiji was Qiqi (淇淇), who died in 2002.
- Family Platanistidae: South Asian river dolphin
Platanista gangetica
South Asian river dolphin (Platanista gangetica)
Where found: The South Asian river dolphins are native to the freshwater river systems located in Nepal, India, Bangladesh, and Pakistan. They can be most commonly found in water with high abundance of prey and reduced flow. The Ganges subspecies (P. g. gangetica) can be found along the Ganges-Brahmaputra-Meghna and Karnaphuli-Sangu river systems of Bangladesh and India, although its range formerly extended to Nepal. A small subpopulation can be still found on the Ghaghara River and possibly the Sapta Kosi River. The majority of the Indus subspecies (P. g. minor) is located between the Sukkur and Guddu barrage in the Sind Province of Pakistan. Two smaller subpopulations have also been recorded in the Punjab and Khyber Pakhtunkhwa Provinces. Since the two river systems are not connected in any way, it is a mystery how these sub-species ended up in the two rivers. It is improbable that the river dolphins made it from one river to another through the sea route since the two estuaries are very far apart. Makes you think God put them there.
Description: The South Asian river dolphin has the long, pointed nose characteristic of all river dolphins. Its teeth are visible in both the upper and lower jaws even when the mouth is closed. The teeth of young animals are almost an inch long, thin and curved; however, as animals age, the teeth undergo considerable changes and in mature adults become square, bony, flat disks. The snout thickens towards its end. The species is effectively blind, although it may still be able to detect the intensity and direction of light. Navigation and hunting are carried out using echolocation. They are unique among cetaceans in that they swim on their sides. The body is a brownish color and stocky at the middle. The species has only a small, triangular lump in the place of a dorsal fin. The flippers and tail are thin and large in relation to the body size, which is about 2-2.2 meters in males and 2.4-2.6 m in females. The oldest recorded animal was a 28-year-old male, 199 cm in length. Mature adult females are larger than males. Entanglement in fishing nets can cause significant damage to local population numbers. Some individuals are still taken each year and their oil and meat used as a liniment, as an aphrodisiac, and as bait for catfish. Irrigation has lowered water levels. Poisoning of the water supply from industrial and agricultural chemicals may have also contributed to population decline. Perhaps the most significant issue is the building of more than 50 dams along many rivers, causing the segregation of populations and a narrowed gene pool in which dolphins can breed. Currently, three subpopulations of Indus dolphins are considered capable of long-term survival if protected.
- Family Pontoporiidae: La Plata river dolphin
Pontoporia blainvillei
La Plata Dolphin (Pontoporia blainvillei)
Where found: La Plata dolphin is found in coastal Atlantic waters of southeastern South America. It is a member of the river dolphin group and the only one that actually lives in the ocean and saltwater estuaries, rather than inhabiting exclusively freshwater systems.
Description: The La Plata dolphin or Franciscana has the longest beak (as a proportion of body size) of any cetacean — as much as 15% in older adults. Males grow to 1.6 m (5 ft, 3 in) and females to 1.8 m (5 ft, 10 in). The body is a greyish brown colour, with a lighter underside. The flippers are also very large in comparison with body size and are very broad, but narrow on joining the body, so are almost triangular in shape. The trailing edges are serrated. The crescent-shaped blowhole lies just in front of a crease in the neck, giving the impression that dolphin forever has its head cricked upwards. The dorsal fin has a long base and a rounded tip. The La Plata dolphin weighs up to 50 kg (110 lb), and lives for up to 20 years. The gestation period is around 10–11 months and juveniles take just a few years to mature. Females may be giving birth by the age of five.
Notes
This honor has significant overlap with Marine Mammals. Why not teach or earn them both at the same time?
References
Wikipedia articles
Other references
- Education, conservation, and research from the world's first cetacean protection organization.
- Marinebio.org
- ↑ Dolphin Senses
- ↑ Baleen Whales: Senses
- ↑ Hooker, Sascha K. (2009). "Toothed Whales. Overview". In Perrin, William F.; Wursig, Bernd; Thewissen, J. G. M.. Encyclopedia of Marine Mammals (2 ed.). Burlington Ma. 01803: Academic Press. p. 1174. Template:Hide in printTemplate:Only in print. http://www.elsevier.com/wps/find/bookdescription.cws_home/716899/description#description.
