Dolphins are cetacean mammals closely related to whales and porpoises.

There are almost forty species of dolphin in 17 genera.

They vary in size from 1.2 m (4 ft) and 40 kg (90 lb) (Maui's

dolphin), up to 9.5 m (30 ft) and 10 tonnes (9.8 long tons; 11 short tons) (the killer

whale or orca). They are found worldwide,

mostly in the shallower seas of the continental shelves and are carnivores, eating mostly fish and squid.

The family Delphinidae, the largest in the order Cetacea, evolved relatively recently, about ten million years ago during the Miocene.

Etymology

The name is originally from Greek (delphís), "dolphin", which was

related to the Greek (delphus), "womb". The animal's name can therefore be interpreted as meaning "a 'fish' with a womb". The name was transmitted via the Latin delphinus (the romanization of the later Greek – delphinos), which in Medieval Latin became dolfinus and in Old French daulphin, which reintroduced the ph into the word. The term mereswine (that is, "sea pig") has also historically been used.

Evolution

Hind limb buds on an embryo in the fifth week of development appear as small bumps near the base of the tail. The pin is approximately 2.5 cm (1 in) long.

Along with whales and porpoises, dolphins are descendants of terrestrial mammals, most likely of the Artiodactyl order. The ancestors of the

modern-day dolphins entered the water approximately 55 million years ago, in the Eocene epoch.

Modern dolphin skeletons have two small, rod-shaped pelvic bones thought to be vestigial hind limbs. In October 2006, an unusual bottlenose dolphin was captured in Japan; it had small fins on each side of its genital slit, which scientists believe to be an unusually pronounced development of these vestigial hind limbs.[21]

Where do dolphins live?

Dolphins live in all oceans and some rivers on Earth.

What do Dolphins Eat?

DOLPHINS!

The food each species eats is different based on where they live.

Dolphins eat fish and some even eat squid.

Large dolphins, like the killer whale (Orca) eat marine animals like seals, sea lions, and sea turtles.

Who Makes up the Dolphin Family?

The male dolphin is called a bull

The female dolphin is called a cow

The baby dolphin is called a calf When in groups they are called

a Pod. Dolphins are Mammals

1. Dolphins are Born with Hair A few hairs on the side of the rostrum (beak). These fall out within the first week.

2. Dolphins Get Water from Their Food. - The fish and squid that dolphins enjoy eating most

have large amounts of water in them and dolphins get it from eating them. Dolphins do not need any extra water because they do not sweat like we do.

3. Different Species - We all recognize the Bottlenose dolphin.There are actually 32 species of oceanic dolphins! There are also 5 species of dolphins living in rivers.

BASIC FACTS ABOUT DOLPHINS

Dolphins are highly intelligent marine mammals and are part of the family of toothed whales that includes orcas and pilot whales. They are found worldwide, mostly in shallow seas of the continental shelves, and are carnivores, mostly eating fish and squid. Dolphin coloration varies, but they are

generally gray in color with darker backs than the rest of their bodies.

Diet

Dolphins consume a variety of prey including fish, squid and crustaceans.

PopulationIt is difficult to estimate population numbers since there are many different species spanning a large geographic area.

RangeMost species live in shallow areas of tropical and temperate oceans throughout the world. Five species live in the world's rivers.

BehaviorDolphins are well known for their agility and playful behavior, making

Did You Know?Like bats, dolphins use echolocation to navigate and hunt, bouncing high-pitched sounds off of objects, and listening for the echoes.

Three Interesting Facts About Dolphins

Most river dolphins are blind, except for the pink dolphin. River dolphins

havesomething that looks like fingers on the tips of their

them a favorite of wildlife watchers. Many species will leap out of the water, spy-hop (rise vertically out of the water to view their surroundings) and follow ships, often synchronizing their movements with one another. Scientists believe that dolphins conserve energy by swimming alongside ships, a practice known as bow-riding.Dolphins live in social groups of five to several hundred. They use echolocation to find prey and often hunt together by surrounding a school of fish, trapping them and taking turns swimming through the school and catching fish. Dolphins will also follow seabirds, other whales and fishing boats to feed opportunistically on the fish they scare up or discard.

Reproduction

Mating Season: Throughout the year, though in some areas

there is a peak in spring and fall.

Gestation: 9-17 months depending on the species. When it is time to give birth, the female will distance herself from the pod, often going near the surface of the water.

Number of offspring:

Usually one calf; twins are rare.As soon as the calf is born, the mother must quickly take it to the surface so it can take its first breath. The calf will nurse from 11 months to 2 years, and after it is done nursing it will still stay with its mother until it is between 3 and 8 years old.

Vocalizations Spectrogram of dolphin vocalizations.

Whistles, whines, and clicks are visible as upside down V's, horizontal striations, and vertical lines, respectively.

Dolphins are capable of making a broad range of sounds using nasal airsacs located just below the blowhole.

THREATS TO DOLPHINS

As climate change causes the seas and oceans warm, dolphins are being seen more frequently in colder waters outside their historic ranges. Due to the rapidly rising ocean temperatures, the dolphin’s primary food sources are seeking deeper cooler waters. Scientists are concerned that the dolphins will have difficulty adapting as quickly as necessary to find new feeding grounds to sustain their populations. Some dolphins that live in areas where rivers and oceans meet, known as brackish waters, are also losing habitat as ocean levels are rising due to global warming.

TherapyDolphins are an increasingly popular choice of animal-assisted therapy for psychological problems and developmental disabilities. For example, a 2005 study found dolphins an effective

Did You Know?To prevent drowning while sleeping only half of the dolphin’s brain goes to sleep while the other half remains

treatment for mild to moderate depression