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11.13: Tursiop truncatus: Bottlenose Dolphin

Created by: CK-12

Common Name

  • Bottlenose Dolphin

Description

The bottlenose dolphin’s scientific name is Tursiops truncates, which means “dolphin with a cut face.” T. truncates has a gray top and a white belly. T. truncates are small cetaceans that have a long snout, a dorsal fin that’s curved like a sickle, and round, sharp teeth. These dolphins are about 9 feet in length. The dolphin’s life span is about 35 years. T. truncates weighs about 440-660 lbs.

Since people polluted the ocean, lots of dolphins have died. We sometimes kill dolphins for their blubber. Boats with propellers can affect their hearing because the propellers are loud, and their hearing is sensitive. The predators of the T. truncates are great white sharks, bull sharks, tiger sharks and killer whales.

The complete taxonomic classification is:

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Mammalia
  • Order: Cetacea
  • Family: Delphinidae
  • Genus: Tursiops
  • Species: T. truncatus

Habitat

T. truncates lives in the Indian Ocean, Caribbean Sea, Mediterranean Sea, Atlantic Ocean, and the Pacific Ocean. T. truncates lives in both warm and cold water. T. truncates follow fish to eat them if they need to.

Biology

Cell Biology

T. truncates (like all plants and animals) has eukaryotic cells. Eukaryotic cells have a nucleus and many other organelles. Organelles are tiny parts within a living cell. One example of an organelle is the nucleus, and another is the ribosome, which makes proteins.

Red blood cells in mammals have no nuclei. The red blood cells carry oxygen better in dolphins than in humans. Hemoglobin concentration in the red blood cell is higher. Nerve cells are used for senses like sight, taste, and movement.

Evolution

Around 500 million years ago, four-legged animals started spending more and more of their time in the water. (An animal with fossil records from around this time named Pakicetus may represent this type of stage). For some reason, this change must have suited them as they gradually evolved, and their bodies changed form so that they eventually lost ability to move on to the land at all. About 30 million years ago, a toothed whale appeared. It appeared to use echolocation. There were various extinct dolphins that were small and medium sized.

Ecology

There are a few sharks that eat dolphins, like the bull shark. There are two other sharks that fight over the animal's carcass. Large species of sharks eat small species of dolphins or calves. The great white and the killer whale (orca ) eat dolphins. T. truncates diet is fish, smaller fish, squid, mullet, shrimp, herring, cod or mackerel, and octopuses. They capture prey by hunting using sight in clear water, detecting noises made by their prey, or by using echolocation. T. Truncatus can have 1-3 babies.

Anatomy and Physiology

Every dolphin has a blowhole, a beak, two eyes, two ears, two flippers, a dorsal fin, two flukes, and a median notch. The auditory cortex of the brain is highly developed for hearing. Blood vessels, nerves and connective tissues are found in the dermis, which is a layer of skin. The outer skin is not waterproof, but consists a soft coating on a hard, fatty inner skin.

Behavior

Baby dolphins rely on their mom’s back when they are first born so that the mom can direct the baby around. They swim in pods. When they are attacked by sharks, they send a caution shriek, meaning back off. When hunting, they sneak up behind the prey, and before the prey knows it, they are attacked. Dolphins are the only other animals that mate almost similar to a human being. They are active during the day and float at the bottom of the sea at night, when they sleep.

References

Attribution

Authors

  • Hailey Andrews
  • Maya Ensley
  • Tania Lloyd

Supervising Faculty

  • Amy Huff Shah

Affiliation

  • Museum School, San Diego, California

Status

  • Published prior to review.

Edit History

  • Created: April 5, 2013
  • Version 1.0 submitted to CK-12: July 9, 2013
  • CK-12 edits: in progress

Level

  • Middle School (grades 6-8)

Opening image copyright by Four Oaks, 2011. Used under license from Shutterstock.com.

Image Attributions

Description

Subjects:

Grades:

6 , 7 , 8 , 9 , 10 , 11 , 12

Date Created:

Jul 18, 2013

Last Modified:

Dec 05, 2014
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