10 Facts About Dolphins

10 Facts About Dolphins
Pink Dolphins

Dolphins are well known for their intellect, their gregarious nature, and their acrobatic abilities. But there are many lesser known qualities that make a dolphin a dolphin. Here we'll explore ten characteristics of dolphins and learn more about these much-loved marine mammals.

1. Dolphins belong to a group of mammals referred to as cetaceans (or Cetacea). The cetaceans are further broken down into two main groups, the toothed whales (or Ondontoceti) and the baleen whales (Mysticeti). Dolphins are classified as toothed whales (Ondontoceti). Other toothed whales include killer whales, pilot whales, beluga, narwhal, sperm whales, and several groups of river dolphins.

2. The term 'dolphin' refers to a diverse assortment of marine mammals. The term dolphin is not restricted to a single taxonomic class and therefore is an unspecific term. The groups of toothed whales whose members are often referred to as dolphins include the oceanic dolphins (Delphinidae), river dolphins (Iniidae), and the Indian river dolphins (Platanistidae). Of these groups the oceanic dolphins are by far the most diverse.

3. Oceanic dolphins are also referred to as 'true dolphins' and are the most diverse group of cetaceans. The species of dolphins that belong to the Family Delphinidae are referred to as 'oceanic' or 'true' dolphins. The Delphinidae group includes about 32 species and is the largest of all subgroups of the cetaceans. Species of oceanic dolphins (Delphinidae) inhabit the open ocean, though this is not a strict rule for the group (in some cases, oceanic dolphins inhabit coastal waters or riverine habitats).

4. Some oceanic dolphins have a prominent beak also known as a 'rostrum'. The snout of some oceanic dolphins is long and slender due to their elongated, prominent jaw bones. Within the dolphins' elongated jaw bone sits numerous conical teeth (some species have as many as 130 teeth in each jaw). Species that have prominent beaks include, for example, Common Dolphin, Bottlenose Dolphin, Atlantic Humpbacked Dolphin, Tucuxi, Long-Snouted Spinner Dolphin, and numerous others.

5. A dolphin's forelimbs are known as 'pectoral flippers'. The forelimbs of a dolphin are anatomically equivalent to the forelimbs of other mammals (for example, they are analogous to arms in humans). But the bones within the forelimbs of dolphins have been shortened and made more rigid by supporting connective tissue. Pectoral flippers enable dolphins to steer and modulate their speed.

6. Some dolphin species lack a dorsal fin. The dorsal fin of a dolphin (located on the back of the dolphin) acts like a keel when the animal swims, giving the animal directional control and stability within the water. But not all dolphins have a dorsal fin. For example, the Northern Rightwhale Dolphins and the Southern Rightwhale Dolphins lack dorsal fins.

7. Dolphins have a unique sense of hearing. Dolphins do not have prominent external ear openings. Their ear openings are small slits (located behind their eyes) which do not connect to the middle ear. Instead, scientists suggest that sound is conducted to the inner and middle ear by fat-lobes located within the lower jaw and by various bones within the skull.

8. Dolphins have excellent vision in and out of the water. When light passes from air to water, it changes speed. The creates an optical effect referred to as refraction. For dolphins, this means their eyes must correct for these differences if they are to see clearly in both conditions. Fortunately, dolphins have specially adapted lens and cornea that enable them to see clearly in and out of the water.

9. The Baiji is a critically endangered river dolphin that inhabits the murky waters of the Yangtze River in China. The Baiji has suffered dramatic population declines over recent decades due to pollution and heavy industrial use of the Yangtze river. In 2006, a scientific expedition set out to locate any remaining Baiji but failed to find a single individual in the Yangtze. The species was declared functionally extinct.

10. Dolphins probably do not have a very strong olfactory sense. Dolphins, like all toothed whales, lack olfactory lobes and nerves. Because dolphins do not possess these anatomical features, they most likely have a poorly developed sense of smell.
Pink Dolphins
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PINK DOLPHINS ANCESTORS

PINK DOLPHINS ANCESTORS

Ancestors:
Ancestors of Inia geoffrensis were a relatively successful marine group, but were displaced during the Miocene period by the appearance of more advanced delphinids. Inia may have entered the Amazon from the Pacific Ocean approximately 15 million years ago, or from the Atlantic Ocean between 1.8 million and 5 million years ago. Their long beaks (often lined with tiny hairs), small eyes, disproportionately large flippers and highly flexible bodies -- once considered "primitive" features -- are now recognized as specialized adaptions to a complex environment.

Soltalia fluviatlis is a warm-water coastal species distributed from the eastern coast of Central America down along the northeastern coast of South America. No one knows for sure when some of these delphinids began to occupy and adapt to freshwater river systems. They are one of the few delphinid species which can move freely between fresh, brackish, and marine waters.
Pink Dolphins

Pink and Gray River Dolphins

Pink and Gray River Dolphins

Of the five freshwater species of dolphins in the world, the pink Amazon River dolphin, Inia geoffrensis, or "bufeo colorado” as they are known in Peru and “botos" as they known in in
Brazil, are considered to be the most intelligent.

These friendly, sensitive, pink dolphins with a brain capacity 40% larger than that of humans, who have lived in harmony with the people of the Amazon and its tributaries for centuries, now face
extinction in some tributaries. What was considered to be one of the least threatened species of dolphins 20 years ago, has now become one of the most endangered species due to the accelerated and commercialized rape of the Amazon basin and the destruction of the South American tropical rainforest.

No one knows the actual number of pink dolphins that live in the Amazon basin, but according to the reseach and studies that Roxanne Kremer has conducted in the Upper Basin of the Peruvian Rainforest, 150 kilometers upstream of Iquitos, Peru, the number of pink dolphins from 18 years ago has risen from eight pink dolphins on the Yarapa River to 35 to 45. Ms. Kremer counted the dolphins in July 1998. ISPTR believes that her work with the Peruvian Forest Police to protection both species of river dolphins, and empowering the local peoples of their rights and use of the law, there has been less illegal commercial fishing and logging in the area, thus saving the natural habitat of the land and aquatic life.

The struggle to save these pink dolphins as an important link in an ecosystem -- currently being encroached upon by industrialized forces -- is being spear-headed by the non-profit
International Society for the Preservation of the Tropical Rainforest (ISPTR), whose first globally known project PARD, the Preservation of the Amazonian River Dolphin.
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Pink Dolphin Physical Description

Pink Dolphin Physical Description

Size: 2.5 to 3 meters (8.25 ft to 9.75 ft) and 90 kilograms (200 lbs.).
Males are generally larger.

Habitat and Distribution: Tributaries and main rivers of the Orinoco River systems of South America. They tend to gather at confluences of rivers.

Reproduction: Pink Dolphin Calves can be born between July and September, but in front of Dolphin Corners, our lodge becomes a nursery for calves during December-February. Calves are born about 75 cm (30 in.) long, and weighing just over 1 kg. (2.2 lbs.) after a gestation period believed to be nine to twelve months. Sexual maturity in males is reached when they are about two meters (7 ft.) long, and females at 1.7 meter (5.5 ft.) at an unknown age

Diet: Crustaceans, catfish and small fresh water fish. A unique characteristic of Inia geoffrensis is the unfused vertebrae in its neck, which allows for the 180-degree head turn, giving them greater flexibility in floodplain forests, grassland, tributaries and shallow waters. Pink Dolphin have a hump on their back instead of a dorsal fin.

Coloration: The reasons for the unique coloration of Inia geoffrensis are poorly understood, but the presence of capillaries near the surface of the skin probably accounts for much of its characteristic pink flush. Other factors may include age of the animal, chemical disposition of the water (especially iron content), and the temperature of the water.
Pink Dolphin
river-pink-dolphins

Biology of River Dolphins

Biology of River Dolphins
About Pink dolphins
Social Habits

Ecological factors strongly influence social behavior. Because Amazon River dolphins do not have any known natural predators -- other than humans -- they do not need to live in large groups, or "pods," protection as many dolphin species.

Inia geoffrensis (pink dolphins) engage in solitary hunting/feeding strategies during the high water season when their prey fishes disperse into the floodplains. At other times, they are found in small "family" groups of 5-8 animals which seem to be led by a dominant adult male. At river confluences, we have seen as many as 35 pink dolphins cooperatively herding and banking fish, often in association with the gray dolphins.

Sotalia fluviatlis (gray dolphins) are strongly gregarious animals and manifest strong social ties with their own kind. Given that they seem to practice a polyandrous breeding system and females tend to be a bit larger than males, they may have a matriarchal social order.
About Pink dolphins
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