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
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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