Dolphin

__ Extinct Animal: Mesonychid __ Future Animal: Flat Dolphin __ Modern Animal: Dolphin __ Dolphins are found worldwide, in temperate and tropical seas, limited to water temperatures of 10 degrees to 32 degrees Celsius. (Refer to Figure 1) Dolphins migrate when the water gets too cold. Certain dolphins show preference to a particular water area because of its temperature, for example, the bottlenose dolphin prefers warmer waters.
 * Introduction: ** Dolphins (Latin name: Delphinidae) are sea animals that are closely related to whales and porpoises. There are approximately 40 species of dolphins in total. Dolphins are very intelligent animals. They have a very friendly appearance and playful attitude.
 * Habitat: **

There are three different types of dolphins: Oceanic Dolphins, Coastal Dolphins and River Dolphins. Oceanic Dolphins can be found in oceans. These dolphins include the Bottlenose, Common and Striped Dolphins. Coastal Dolphins are found in the coastal water areas, these include the Pacific, Tucuxi, and White-Beaked Dolphins. Lastly, the River Dolphins are found in rivers. They include Indus River and Tucuxi dolphins.

The climate that dolphins like to live in depends on different species of dolphins. There are specific dolphins for each environment. The climates they like to live in range from the cold waters in the North Pole and tropical waters in the Caribbean.

Dolphins eat a wide range of sea animals, such as fish, squid, shrimp and other [|crustaceans]. (Refer to Figure 2) They swallow their food without chewing. Adult dolphins eat about 4% to 6% of their body weight in food every day. They have the ability to digest food very quickly.



The predators of dolphins include large shark species, such as tiger sharks and bull sharks.

Dolphins communicate with others by making a particular sound using their nasal airsacs that are located below the blowhole. By communicating, they are able to find food, as well as talk to each other. Dolphins that are in tanks for many years lose this ability, because they become deaf from their own echolocation. The environmental factor that caused this could have been because of the water environment. When they are in shallow water environments, they can use their echolocation ability to locate food and communicate.
 * Adaptations 1: Echolocation **


 * Adaptations 2: Eyes **

Dolphins rely more on sound than sight. They have spherical lens, which allow them to have a better vision when they are very deep under water, when there’s minimal light. They produce greasy tears, which protect their eyes from the salt in the water. This helps it to survive by having a better vision on preys and being able to watch out for sharks and other large sea animals otherwise it might get eaten by other animals. The environmental factor that caused this could have been the water environment. The salinity of the water has increased, and they need to protect their eyes in order to survive.


 * Adaptations 3: Blowholes **

Most Cetaceans’ blowholes have evolved to the top of their heads. Dolphins seal their blowholes to prevent water from going in while under water. Their lungs are very efficient in absorbing oxygen. This allows them to inhale quickly and stay under water for a very long time. This helps it survive by giving it oxygen otherwise it might drown. The environmental factor that caused this could have been the depth of the sea. Instead of having to lift their heads every time they wanted to breathe, they could now breathe easily though the blowhole at the top of their heads.


 * Adaptations 4: Tails **

Dolphin’s tails allows it to move water in a quick speed, using less energy. The up down motions that the tail makes allow the dolphins to move faster and easier. Research has shown that a dolphin’s tail is capable of creating six times more force than an Olympic swimmer. Their tails help them survive by allowing them to move away from predators as quick as possible, as well as catching fishes to eat. So they won’t starve and get eaten.


 * Adaptations 5: Skin **

Dolphins have very smooth skin, which allows the dolphins to move around in the water very quickly. This helps it survive as it can locate the prey and hunt it down very quickly so it won’t starve to death. The environmental factor that caused this could have been the speed of the prey; their skin helps them to quickly chase their prey. 1) American Cetacean Society (2010) Bottlenose Dolphin. Retrieved 26th June, 2011, from [] 2) Facts about Dolphins (N.D.) What Climate Do Dolphins Like to Live In. Retrieved 26th June, 2011, from [] 3) ThinkQuest (1998) Evolution of Dolphins. Retrieved 26th June, 2011, from [] 4) Victoria Whale Watching (N.D.) History of Dolphins. Retrieved 25th June 26, 2011, from []
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