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Our Dolphin Friends and Their Distinctive Features

written by: ciel s cantoria•edited by: Donna Cosmato•updated: 11/29/2010

Discover several interesting facts about these fascinating creatures, so you can be aware of how human activities could cruelly impact their existence.

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    General Dolphin Traits

    Leaping dolphins 

    • Dolphins, along with whales and porpoises, belong to the mammalian order of marine animals known as cetaceans.

    • As a cetacean, the dolphin family is known as Delphinidae. Most, but not all, have distinct beaks called rostrums. They have a set of cone-shaped teeth, and their bodies are covered with thick, hairless and glandless skin, which is kept smooth by the constant sloughing-off of the outermost skin layers.

    • Dolphins are carnivores; they feed on fish and other invertebrates like cuttlefish, squids, octopus, crabs, shrimp, and lobsters.
    • Each type of dolphin has to find its habitat according to an ecosystem by which its characteristics fit.
    • The speed at which dolphins swim with the aid of their flippers and powerful tails depends on their habitats and prey. The coastal types move at about 10 miles per hour (mph), while the oceanic kind have the ability to move as fast as 15 to 25 mph.
    • Dolphins travel not just by swimming alone, but also through leaps and bounds; some of them spin while diving in and out of the water.
    • Others have been observed riding the bow waves of fast-moving sea vessels as their way of gaining speed.
    • A dolphin-calf is born with its tail part coming out first, while its eyes are already wide open and alert. This is necessary for the calf’s survival because it has to follow its mother immediately on the way up to the surface in order to catch its very first breath of air.
    • Although some suggest the dolphin’s level of intelligence is comparable to that of the regular human, other marine scholars caution that this should not be taken as a generality among dolphins. Its habitat and environment are influential factors to a dolphin’s mental capabilities, and most of their survival skills were developed and adapted according to their home waters.
    • Dolphins emit clicking sounds through their blowholes, which tend to echo or resonate. The resonating sounds often catch-up with the succeeding clicking hums and thus produce a distinctive sound. Marine scientists call this behavior, echolocation, in which the sound waves bounce back from the waters to the dolphin’s ears. Their ears send messages to their brains, which create an acoustic vision that enables the dolphin to estimate the time and distance needed to reach their target. For more details about echolocation among these mammals, refer to “Hearing Your Way Around: Echolocations in Whales and Dolphins.
    • The Delphinadae are known to be very sociable and have been observed to form long-lasting bonds with their fellow dolphins. A small group of delphinids, called pod, can have from two to up to forty members. The large groups, on the other hand, are called schools or herds, comprising several hundreds up to thousands of different types of dolphin species in a single group.

    At this point, we discuss the features which make one type of dolphin different from the others. The following sections provide a cursory view of these distinctions, and examine each type's current conditions in our present-day environment:

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    The Different Types of Dolphins

    800px-Girl playing with Bottlenose Dolphin Tursiops Truncatus 

    1. The Bottlenose Dolphin

    Take note of this delphinid’s image on your left, and notice how its stubby beak closely resembles a bottle’s neck; hence, earning for itself the moniker bottlenose. This species’ vertebral-structure is different from the other oceanic dolphins, as five out of its seven vertebrae are not hinged together, thus making the dolphin’s neck more flexible.

    Learn about these species' other distinct habits and current status by reading “Bottlenose Dolphins Endangered Species".

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    800px-Witsnuitdolfijn - Lagenorhynchus albirostris whitebeaked 

    2. The White-Beaked Dolphin

    Although described and called white-beaked, the color of its rostrum borders more on grey. The white part is located in the belly area and on both sides of its flanks. This type of dolphin is found in the sub-arctic parts of the ocean; mostly, in the North Atlantic, off the Norwegian coasts, in the Baltic Seas, and occasionally along the Spanish coasts.

    Observers have noted a marked decrease in the overall population of the white-beaked dolphins as hunters and fishermen in Newfoundland, Labrador, Greenland, and the Faeron Islands hunt and kill them, albeit not for commercial purposes. However, a corresponding increase in their population was noted in the European region, which could be interpreted as a migratory move by this species.

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    This page of our article about the different types of dolphins contains brief descriptions of Pilot Whales, Risso's, Spotted, Orcas, Hourglass and Heaviside Dolphins. Read overviews on how each species' population is affected by pollution and degradation problems as well as human activities that prey on them for human consumption and commercial purposes.
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    800px-PilotWhale Short Finned 

    The Different Types of Dolphins (continuation)

    3. The Short-Finned Pilot Whale

    The features of this short-finned delphinid are somewhat whale-like for its lack of beak, the presence of a prominent bulge on its forehead and its rounded head. Their teeth are noticeably larger than those of the other dolphin species and are framed by a distinctively oblique mouth.

    They are commonly found in tropical offshores or where the water temperature is relatively warmer; hence, a large number of them can be found in the Gulf of Mexico. A pilot-whale dolphin's pod is considered a noisy lot because the members make plenty of squealing, smacking, whistling, whining, and snoring sounds. Nonetheless, scholars distinguish this species as highly communicative.

    Although mass-stranding may occur during severe storms, this dolphin species manages to survive by taking shelter along the in-shores. Currently, their population remains steady in numbers.

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    Grampus griseus Risso's dolphins 


    4. Risso’s Dolphin

    Risso’s dolphins are recognizable by their heavily-scarred bodies and by their blunt and almost square-shaped heads. However, from a distance, they could be mistaken for killer-whales because of their size and tall dorsal fins.

    This species of Delphinadae are scattered across the western Atlantic, in Newfoundland, and along the Canadian and American east coasts. Their large numbers inhabit other parts of the globe including the Indian Ocean, from along the African coasts to the Bay of Bengal, through Indonesia and Sri Lanka.

    Risso’s dolphins are known to interrelate with other cetaceans, particularly with the bottlenose herds. Although there are records showing cross breeds of dolphin species, their hybrids are feared to have been taken in captivity. Currently, the population of Risso’s dolphins remains relatively regular in numbers.

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    Pantropical spotted dolphin 

    5. Pantropical Spotted Dolphins

    These are small dolphins with black rings around their eyes and a short black beak with a black stripe across the base. The whiteness of its abdomen makes the black spots very noticeable. In contrast, its black upper body parts are peppered with white spots.

    These types of dolphins are prevalent in tropical and subtropical waters and are found abundantly in the Pacific, where they are frequently victimized by tuna-seining sea vessels. However, the mortality rates subsequently decreased as the territorial governments strictly implemented laws and programs that aim to lower the numbers to less than 5,000 dolphin lives lost annually.

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    6. Long-Finned Pilot Dolphins

    These dolphins inhabit the in-shores and bays of North Carolina during the summer but are largely predominant in Iceland’s and Greenland’s offshore waters. Owing to their large and bulbous melon-shaped body, they are often mistaken for whales, but they are definitely different because of their exceptionally long flippers. A grayish white stripe diagonally appearing behind their eyes adds to their distinctive features.

    Due to their similarity to whales, they are affected by the whaling activities in the Nordic areas.

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    448px-Type C Orcas 

    7. Orca or Killer Whales

    Some readers may be surprised to know that the Orcas, or killer whales, are actually dolphins. Their large, paddle-like flippers and the white patch around their eyes are the identifying marks that distinguish them from among other species. To learn more about these killer whales, read “Interesting Facts about the Orca Whales".

    Another article, “Why are Killer Whales Endangered?", furnishes a report about the unfortunate circumstances that are causing this dolphin species to dwindle in numbers.

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    8. Hourglass Dolphin

    This delphinid has an hourglass silhouette pattern on its flanks; hence the hourglass name. In addition, they inhabit only the Southern Hemisphere and are found largely in Antarctica. Nonetheless, they can migrate as far as Australia, New Zealand, and South America.

    Hourglass dolphins are the least of the species to encounter any threats because they prefer to stay in-shore most of the time.

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    9. The Heaviside Dolphin

    This dolphin species is often mistaken for a porpoise because of its small and robust body and lack of beak. However, the remarkable lines that separate into a fork-like pattern on its belly and the grayish black cape over its head serve as their identification as a Heaviside delphinid.

    These dolphins prefer to inhabit the cold, shallower parts of the waters of the Benguela Current and hardly stray away from it or even migrate. However, researchers find it difficult to track or monitor their population or any possibility of endangerment, since there is not enough data provided by South Africa, Angola, and Namibia where large numbers of Heaviside dolphins exist.

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    Page three of the examination of different types of dolphins contains brief descriptions of False & Pygmy Killer whales, Commerson's, Striped, Peale's, Melon-Headed, Irrawaddy, Frasier's and Hector's Dolphins. Learn about their distinctive features and their current status in today's environmental conditions.
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    484px-Pseudoorca Crassidens false killer whale 

    The Different Types of Dolphins (continuation)

    10. False Killer Whale

    Obviously, this dolphin earned its name due to its large resemblance to the Orca, but it could be easily identified by its mostly black color around the surface-visible parts of their bodies. The inner sections are of a lighter grayish-black shade.

    It is generally believed that the false killer whales are near-extinct because only a few have been visible in recent years. The toxicity of the ocean’s contaminants and over fishing activities are considered the causes of its disappearance.

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    11. Commerson’s Dolphin

    The Commerson’s dolphin is a sociable and outgoing delphinid species, and it prefers to frolic in the coastal waters of the Falkland Islands, Tierra del Fuego, and the Straits of Magellan. Typically black with white Piebald-like patterns, this dolphin is characterized by a blazing white forelock sweeping through its midsection. Its wide and rounded dorsal fin is another identifying mark.

    They can migrate as far as Chile and Argentina but are threatened by poachers who purposely kill them for their meat, which is used as crab bait.

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    12. Striped Dolphins

    These delphinadae are easily recognizable by the stripe that begins from their beaks running down through their flanks. They largely inhabit the major bodies of water, particularly the Atlantic and the Pacific Oceans and the Mediterranean seas. These marine creatures are well-loved for their acrobatic nature; they playfully flip, spin, leap, and plunge into the water in an upside down position.

    There are no known threats against their population’s existence.

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    714px-Lagenorhynchus australis Peale's 

    13. Peale’s Dolphin

    The main distinguishing marks of this dolphin species are the double black rings around its eyes extending toward the rostrum. This dolphin is a bow wave-rider, and an acrobat often observed in the company of Risso’s and Commerson’s dolphins in the Straits of Magellan. However, they prefer to nest in the cool open coastlines.

    They are also threatened by poachers around Tierra del Fuego, who kill them for their meat. Overfishing of crabs in the areas resulted in the recent lack of zealousness in poaching activities.

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    14. Pygmy Killer Whale

    This dolphin is named by virtue of its character, since it has manifested aggressiveness and killer instincts by fatally attacking its fellow-dolphins. As an example, a pygmy killer whale in conservation killed a pilot whale which arrived to share the tank the pygmy was occupying. The cause of death was established as a sharp blow to the pilot whale's cranium with the use of the killer whale’s head.

    Its main distinguishing features are the white lips and the white lower jaw, which resembles a goatee. Refer to illustration number one of this photo image. They can be found inhabiting the Gulf of Mexico, the Indian and Southeastern Atlantic Ocean, and around Sri Lanka and the Lesser Antilles.

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    Melon-headed whale large 

    15. Melon Headed Whale

    This species closely resembles the pygmy killer whale in size, shape, and color but a closer look at its face shows that it has a black widow’s peak-like mask on its face and none of the pygmy’s white goatee.

    They inhabit mostly tropical and subtropical waters and are abundant in the Philippine Sea. There are no known reports of threats or endangerment to the population of the melon-headed whales.

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    Faunapesutmahakam irrawaddy 

    16. The Irrawaddy Dolphins

    These delphinadae have the typical features of other dolphins, and their main distinctions as Irrawaddy species are their anatomical structures. They have no cardiac sphincter muscles, and their stomachs are divided into sections. They prefer to inhabit the coastal waters of Southeast Asia, Papua New Guinea, and Northern Australia.

    The pods and herds inhabiting the Mekong River and Songkhla Lake are listed as critically endangered. Accordingly, they are affected not only by human activities like the constructions of dams and barges, which destroy their habitats, but also by the polluted waters in the area.

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    17. Hector’s Dolphin

    These dolphins are one of the smallest of all delphinid species and are found only in New Zealand’s waters. Conservation efforts for their preservation have proven successful, since there are no reports of threats and endangerments.

    Fraser s group.jpg 

    18. Frasier’s Dolphins

    These types of delphinids are mostly grayish brown in color, and their identifying marks are the stripes on their backs and on their faces. There is not enough information about their distribution, but they have been frequently sighted around near-equator areas of the eastern Pacific. Reports are that they fall victim to the harpoons of Indo-Pacific poachers for both commercial and human consump