ORGANISM PHYSIOLOGY PAPER 1

Organism Physiology Paper

Kim Eschler

BIO 101

July 5, 2011

Olivia Uitto

ORGANISM PHYSIOLOGY PAPER 2

Organism Physiology Paper

Kingdom: Anamalia, Phylum: Cordata, Class: Mammalia, Order: Cetacea, Sub-

order: Odontoceti, Family: Delphinidae, Genus: Delphinus, Species: delphis, or better

known as, Dolphin. Dolphins occupy all oceans and major seas, even some are in

larger river systems. This paper will cover characteristics of a dolphin, the ancestry to

the modern dolphin, and what adaptations the dolphin has gone through to be the

survivor it is today.

Characteristics.

Dolphins are very social creatures and use interaction for the purpose of hunting,

defense, and reproduction. Normally a dolphin will stay in a long-lasting group of 2-40

animals called pods, but larger groups of hundreds of dolphins have been reported and

those are called herds. Dolphins are carnivores that feed on fish, squid, octopus,

cuttlefish, crabs, shrimps, and lobsters. Dolphins are food for sharks, killer whales,

humans. Man is the most dangerous predator for the dolphin. Humans will kill dolphins

for their meat, their fat, even for being in the area they are fishing. Additionally, studies

are currently being done to evaluate the affect of pollution in the water on dolphins.

Dolphins bear live young, and the mother nurses the calf with her milk and

provides care. The calf is nursed one and one half to three years and a mother will stay

with her young three to eight years. Dolphins are believed to live about 30 years.

Dolphins vary based on their ecosystem and what is required for them to survive in their

niche.

In the Gulf of Alaska there are few dolphin species, one of which is the pacific

white-sided dolphin. This dolphin has a short, rounded beak with about 30 curved teeth

ORGANISM PHYSIOLOGY PAPER 3

in each side of the jaw. Very energetic and is seen frequently leaping, belly flopping and

summersaulting. It is attractively marked with a black back, gray sides and white stripes

from its eyes to its tail. Its dorsal fin is tall and sharply hooked, its flippers are small and

rounded at the tips, and its flukes have a notch in the center. They are seven to eight

feet in length and weigh up to 300 pounds.

Beginnings.

(EO.Reddit.com, 2011)

All dolphins, whales, and porpoises are related. Fossil evidence has been found

from the early Eocene epoch that indicates early dolphins were already aquatic 45-50

million years ago. It is believed that animals that spent a great deal of time looking for

food around water areas went through an amphibious stage before becoming

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committed to the water. Once in the water records show that by changes in their teeth it

took millions of years for true cetaceans to develop.

Adaptations.

(Animalfiles.com, 2011)

The dolphin has come a long way from the once amphibious animal it is believed

to have evolved from. Fossil evidence shows that once early dolphins decided to be

aquatic, it did not take long for bones of the hind limbs to disappear. Anatomically,

dolphins’ bodies have become more streamlined to move in the water. Their front limbs

evolved into flippers and their powerful tail is their main propulsion mechanism.

They have a thickened body with a raised head that caused the vertebrae neck

to fuse together. Instead of a major blood supply to the brain on the outside of the neck,

the dolphins blood flows through an artery in the vertebrae that provides a constant

supply of blood, which is most essential when diving into the depths of the ocean.

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The dolphins’ skin is extremely smooth, hairless, is thick, and lacks glands. This

skin is kept smooth by constantly sloughing off and being replaced. On average their

skin is replaced at a rate nine times faster than a human, and in the case of the

bottlenose dolphin, the outermost layer of skin is replaced every two hours.

Dolphins tent to rely on their sense of hearing to survive. They are said to have

good eyesight, but in the blackness of the ocean, other senses have had to develop for

survival. The shape of the dolphins melon (the fatty tissue in front of the blow hole) acts

as a lens to focus sound when the dolphin produces high pitched clicks for

echolocation. When the sound comes back the small bone under the chin, called the

pan bone, receives the sonic report and stimulates the brain via the inner ear. With

echolocation the dolphin can judge distance by measuring the time between emitting

the clicks and the return. With this amazing skill, dolphins can determine the size,

shape, direction of movement, and distance of objects in the water.

Conclusion

The dolphin has adapted well to its watery world, and evolved in shape and skill

to breed successfully and thrive. The fascinating skill of echolocation gives the dolphin a

huge advantage when feeding in the darkness of the ocean. Dolphins are very

energetic, kind, and smart animals. For the most part they are left alone in their

ecosystems and traditionally only humans to fear.

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References

American Cetacean Society (2011). Pacific White-Sided Dolphin. Retrieved on June 27,

2011 from http://www.acsonline.org/factpack/PacWhiteSided.htm.

Animal Files.com (2011) Anatomy of a Dolphin. Retrieved on June 28, 2011 from

http://www.theanimalfiles.com/anatomy/dolphin_anatomy.html

EO.Reddit.com (2011) Evolution Timeline of a While and Dolphin. Retrieved on June

28, 2011 from eo.reddit.com/r/todayilearned/comments/dq4v7/til_the_evolution_

timeline_of_whales_and_dolphins/

Looney, Z. (1996) Dolphin Evolution. Retrieved on June 27, 2011 from

http://tursiops.org/dolfin/guide/dolphinevo.html