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Evolution of a Dolphin

by Taylor Alessia and Sierra & Isabelle

taylor starr

on 26 October 2012

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Transcript of Evolution of a Dolphin

The Evolution of the Dolphin By Alessia, Sierra,Taylor
& Isabel The Dolphins Intermediate Species Evolution of the Dolphin: Future 1. Natural Selection the common ancestor of the dolphin is the Pakicetidae.
the intermediate species of the dolphin are the Ambulocetidae, Remingtonocetidae, Protocetidae,Basilosauridae, Dorudontidae
the four-legged mammals ventured into the water in search of food and shelter
as eons passed, changes arose in these intermediate species: front legs developed into flippers, nostrils moved to the top of the head (which are now called blow holes), the tail enlarged into flukes, smooth blubber replaced hair and the mammal developed an enormous body that became buoyant in the water Natural selection refers to the traits that help an organism survive the pressures of a particular environment
The intermediate species of the dolphin developed these traits so that they would better suit the environment that they had transferred to
The Remingtonocetidae differs from the Abulocetids because they have smaller eyes, long slender snouts and wide separated ears
These widely separated ears and their small eyes may have been an adaptation in order to hear and locate their prey.
All of these traits have allowed this species of dolphins to evolve and adapt to its environment. The Environment of the Dolphin Live in shallow waters (rivers and oceans) all around the world
Temperature ranges from 10 degrees C to 32 degrees C (50-90 F).
The amount of salt in the water makes it 800 times more dense than air. Characteristics of a Dolphin Skin color is gray to dark gray on its back, fading to white on its lower jaw and belly.
Pectoral flipper length averages 30 to 50 cm (11.7–19.5 in.).
Generally 2-3.9m (6.6-12.8ft).
150-200kg (331.5-442lb).
Full grown males are slightly longer,while females are considerably heavier.
Sleek, streamlined, fusiform body.
Outer skin layer, is 10 to 20 times thicker than terrestrial mammals. 1. The Dolphin lives in cold, deep waters.
2. Ocean water is 800 times more dense than air.
3. Dolphins breathe through gills.
4. Natural Selection happens in patterns and we can predict what traits the next generations will have.
5. Its ancestor is the Pakicetidae
6. Different species of dolphin live in different oceans.
7. The intermediate species of the dolphin are the shark, tuna, salmon, and goldfish.
8. Dolphins come from land animals.
9. Dolphins are the smallest aquatic animal.
10. The bones that made up the legs of the Pakicetidae are now the bones that make up the pelvis of the dolphin. True & False Questions Dolphin Facts Did you know...
Dolphins have to be conscious to breath.[This means that they cannot go into a full deep sleep, because then they would suffocate. Dolphins have "solved" that by letting one half of their brain sleep at a time. This is because they have gone through natural selection in order to survive
dolphins have to come up to the surface to breathe? Most dolphins surface every few minutes, but they can stay under water for up to 15 minutes. A dolphin breathes through the blowhole on top of its head.
It is difficult to estimate population numbers since there are many different species across a large geographic area
not all dolphins live in seawater? There are some species that live in fresh water: the river dolphins. Unfortunately, river dolphins are critically endangered and it is even feared that one species, the baiji, has already died out. - we believe that in the future it may be possible for dolphins to gradually, over a long period of time become terrestrial species once again.
-This is due to the pressures within the environment
-We believe that dolphins will mutate and grow back their legs allowing them to survive on land. This is very possible because the pelvic bone they once used for their legs remains inside their bodies. When a mutation occurs during natural selection it is likely that a switch can turn on and make the pelvic bone become a bone used for legs once again.
-If there was a shortage of food supply on land millions of years ago making land animals evolve to aquatic animals, then could it not be possible for it to happen again within the oceans?
-there are thousands of species of fish that dolphins can eat. however, if a natural disaster such as a hurricane, earthquake, tsunami, mudslide, oil spill or volcano were to occur, then the bottleneck effect would take place. this natural disaster would then wipe out the vast majority of the aquatic species population, making it difficult for dolphins to find food to survive.
-Therefore they would be pressured to move onto land to find food to ensure their survival. Evolution of Dolphins:
Future Extended - Dolphins are an example of allopatric speciation because all dolphins live in water but the regions of the ocean which they live in are too far for them to swim to one another
- Although it is very possible that a beneficial mutation could occur in the population where they are able to swim those far distances
- If that could happen then they could reproduce with species found in different parts of the oceans and the genetic variation would increase
- Natural selection happens by random chance and we cannot determine what mutation a species might get next, but we can make predictions based on the factors in the environments they live in Advantages of Characteristics
Fin shape: a dolphin's tail goes up and down to help it dive up to get air (compared to a fish's back fin which moves side to side). The shape of their fins also helps to propel them through the water. their forefins and dorsal fin are used for steering.

To help dolphins save oxygen while they dive underwater, their heart beats slower during a dive and their blood travels from other parts of the body to their heart, lungs, and brain.

Dolphins also save oxygen through their muscles, which have a protein called myoglobin, this protein stores oxygen. Dolphins have a number of characteristics which help them to survive. Dolphins have blubber, or fat, which provides insulation, helping the dolphin stay warm in cold water and helps them to heal small wounds.

Blubber also serves another function, streamlining the body for better speed in the water.

Dolphins have a body covering of skin (not scales). The upper layer of the skin produces an oil which forms a film that covers the dolphin's whole body.

Being mammals, dolphins breathe with lungs rather than gills, so they breathe from a blowhole which closes before the dolphin goes into the water, so water will not enter the blowhole.

The long nose helps the dolphin to kill sharks. Dolphins have teeth, which they use to catch fish.
Dolphins have large brains in relation to the size of their bodies, and studies show they are very intelligent mammals.
Dolphins work together to find food. they gather schools of small fish by herding them up onto reefs and sandbars. The dolphins then work together, taking turns to feed while the other dolphins keep the fish herded.
Dolphins have well developed echolocation.this is how they locate other animals or objects in the water. this is also how they communicate with each other. Dolphins are believed to evolve from mammals that once lived on land. One of these terrestrial ancestors is called the Pakicetus. It is the oldest ancestor of a dolphin which lived 65 million years ago.
The Pakicetus looked like a wolf. Skeletons were found in Pakistan (hence their name) show that the ear region of the skull looks similar to fossil whales and modern whales.
The shape of the ear region in the Pakicetus is very unusual and it only resembles the skulls of whales.
It is believed that the ancestors were land mammals because they still have certain land features such as they breathe in air, they have traces of hind legs and the shape of their spine tells us that their ancestors ran on land and did not live in water. The Pakicetus
(the common ancestor) The hind limbs of the Basilosauridae were still present but they were tiny. They had feet with three toes and their pelvis had become detatched from their vertebrae. This meant that they could no longer support their weight on land.
The Mysticeti are characterized by having baleen plates for filtering food from water rather than having teeth. This distinguishes them from the Odontoceti, or toothed whales.
The Odontoceti are identified by their dorsal fins. The Mysticeti are identified by their tail fluke patterns. The Odontocetes are usually smaller and more agile that the Mysticeti. Works Cited "DOLPHINS." ThinkQuest. Oracle Foundation, n.d. Web. 25 Oct. 2012. <http://library.thinkquest.org/3935/DOLPHINS.HTM>. "Dolphin Evolution." Dolphin Evolution. N.p., n.d. Web. 25 Oct. 2012. <http://understanddolphins.tripod.com/dolphinevolution.html>. "Evolution of Dolphins." Dolphin Way. N.p., n.d. Web. 25 Oct. 2012. <http://www.dolphin-way.com/dolphins-%25E2%2580%2593-the-facts/evolution/>. "RemingtonocetidaeWhales Endemic to the Indian Subcontinent." Remingtonocetid. N.p., n.d. Web. 25 Oct. 2012. <http://www.neomed.edu/DEPTS/ANAT/Thewissen/whale_origins/whales/Remi.html>. "Facts About Dolphins." About.com Animals / Wildlife. N.p., n.d. Web. 25 Oct. 2012. <http://animals.about.com/od/cetaceans/a/dolphin-facts.htm>.
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