Whales and Dolphins

 

Common Dolphin

Common Dolphin

  (Delphinus delphis)

The Common Dolphin has a criss-cross pattern well defined on its side, similar to an hour glass shape. The previous segment is yellow, while the subsequent is gray. The surface dorsal is black and the womb is white.

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Bottlenose Dolphin

Bottlenose Dolphin

The body of this dolphin is long and somewhat chubby. Dorsal fin is dark grey and white or pinkish.

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Striped Dolphin

Striped Dolphin

  (Stenella coeruleoalba)

This dolphin is a member of the family Delphinidae. Its body is fusiform with tall dorsal fins, long and narrow flippers and a prominent beak. It is identified easily from other Delphinidaes and by their distinctive coloring. They are typically bluish- gray in colour with a dark gray dorsal cape and a coloration of white. It is called the "Striped Dolphin" due to the strip of bluish black colour, that runs the across the entire length of its body, from the eye to the tail, and it possesses a dark flipper.

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Pilot Whale

Pilot Whale

  (Globicephala melas)

The body in Pilot Whales is robust, with a thick tail stock. The melon is exaggerated and bulbous and the beak is barely discernible or non-existent. The dorsal fin is wide, broad based, falcate and set well forward on the body. The flippers are long, slender, and sickle-shaped, typical of this species. Its size and shape are depending on the animal age and sex, being the dorsal fin more bulbous in males than in females; and also thicker and wider. Female dorsal fin is then straighter

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Killer Whale

Killer Whale

  (Orcinus orca)

Killer Whales are robust animals. The head has a characteristic bulbous melon. The flippers are highly mobile and rounded, looking like large paddles. The most striking feature is the large dorsal fin. It is tall (1.8 m or more) and triangular in males and may even be curved slightly forward. In juveniles, the dorsal fin is smaller and falcate (sickle shaped).

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Sperm Whale

Sperm Whale

  (Physeter macrocephalus)

This whale has a very distinctive, huge squarish head occupying at least one-third of its body and projecting, often up to 1.5 m, well beyond its lower jaw. The large head contains a cavity called the spermaceti organ which is a mass of web-like tubes filled with a yellow wax. This organ is believed to be used in maintaining buoyancy and may also be used to focus sonar clicks.It has a huge brain that weights about 9 kg. It is the largest brain of any animal.

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Fin Whale

Fin Whale

  (Balaenoptera physalus)

The Fin Whale is long, sleek, and streamlined, with a V-shaped head, which is flat on top. A single ridge extends from the blowhole to the tip of the rostrum (upper jaw). There is a series of 50-100 pleats or grooves on the underside of its body extending from under the lower jaw to the navel. The Fin Whale has a prominent, slightly falcate (curved) dorsal fin located far back on its body. Its flippers are small and tapered, and its fluke is wide, pointed at the tips, and notched in the center.

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Cetaceans

Dolphins and Whales are MAMMALS included in the Cetacea order, which represents the highest adaptation level for life underwater, being completely land independent. Mating, feeding and any other behaviour take place under the water.

The words "whale" and "dolphin" are misleading. They have no real scientific basis and are the cause of much confusion. For example, Pilot Whale is a member of the dolphin family, Delphinidae, so they should really be called "dolphin". The solution is to think of modern cetaceans in terms of two distinct groups: the toothed whales, or odontocetes, which possess teeth; and the baleen whales, or mysticetes, which do not. These groups have a strong scientific basis, and avoid all the confusion associated with "whales" and "dolphins". The main differences between the two groups are:

Mysticeti Odontoceti
No teeth. Instead they have keratin baleen plates, suspended from the roof of the mouth. All species have teeth. The number of teeth varies from 2 in some beaked whales to more than 250 in some dolphin species.
Two nasal openings (or blowholes) Single nasal opening (or blowhole)
The skull is symmetrical. The skull is asymmetrical.
The melon is present only in the fetal stage and absent or poorly developed in adults. They have no echolocation capabilities. The melon is well developed. It plays a major role in echolocation.

 

Characteristics

The vast majority of cetaceans are odontocetes. There are 70 species in all. The number, size and shape of their teeth vary enormously. In the main, odontocetes feed on fish and squid, although some also take a variety of crustaceans, and a few take marine mammals. The mysticetes comprise the remaining 11 species, including many of the large and most popular whales, such as the blue, grey, humpback and right whales. Instead of teeth, they have hundreds of furry, comb-like baleen plates, often referred to as whalebone, which hang from their upper jaw. These are tightly packed inside the whale's mouth, and have stiff hairs that form a sieve-like structure to filter food out of the sea water. Mysticetes feed mainly on small schooling fish or crustaceans, such as krill and copepods.

There are other, more subtle, differences between odontocetes and mysticetes. Toothed whales, for example, are recognizable by their single blowhole, while baleen whales have two blowholes side by side. Like other mammals, cetaceans maintain a constant warm internal temperature (37ºC). Blubber insulates against the chilling effects of water and heat-conserving counter current exchange systems reduce heat loss in blood that circulates near the surface.

The two types of oral structure are related to their kind of diet:
  - The Mysticetes are filters: possess wide, large mouths and baleen plates.
  - The Odontocetes are hunters: possess serrated and fine teeth.
In general they have a "vocal" repertoire. The Mysticetes use this sound only to communicate among themselves, but the Odontocetes have an additional range of high frequencies by using sonar.

The Blue whale (Balaenoptera musculus) is especially well known for being the largest mammal that exists to our knowledge. It can reach 30 meters in length and weigh 180 tons.


Phylogenetics Classification

Suborden Familia Subfamilia Descripción
Mysticeti
Cetaceans with baleen plates
Balaenidae   Right whales and Groenland whale
Balaenopteridae Balaenopterinae Fin Whale and Blue Whale
Megapterinae Humpback whale
Eschrichtiidae   Gray Whale
Neobalaenidae   Pygmy whales
Odontoceti
Cetaceanswith teeth
Delphinidae   Dolphins and killer whales
Platanistoidea   River Dolphins
Phocoenidae   Porpoises
Physeteridae   Sperm Whale
Kogiidae   Pygmy and Dwarf Sperm whales
Ziphiidae   Beaked whales
Monodontidae   Beluga and Narwhal