http://www.ck12.org Chapter 11. Understanding Biodiversity: Animals: Mammals
Habitat
T. truncateslives in the Indian Ocean, Caribbean Sea, Mediterranean Sea, Atlantic Ocean, and the Pacific Ocean.T.
truncateslives in both warm and cold water.T. truncatesfollow 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 namedPakicetusmay 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. truncatesdiet 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. Truncatuscan 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