1. Order Sirenia I am extinct but I am related to manatees.
What order am I in?
Order
Sirenia
This is a picture of the extinct Stellar’s sea cow

2. Identify
behavior
Spy-hopping

3. 1. Nasal sacs
3. Melon
2. Blow hole
4. Middle ear

4. What is the function of this
red blood cell?
Red blood cells transport
oxygen to the tissues
What is the oxygen carrying
pigment in this red blood cell?
Hemoglobin

5. Weddell seal
The spleen of a Weddell seal can store up to 4 liters of blood. This blood
serves as a reserve supply of oxygen. (Note that the total
blood volume of humans is only 4 –6 liters.)
Antarctica
2. Weddell seals have twice as much blood per pound as humans.
3. Myoglobin is an oxygen carrying pigment found in muscle cells. Diving marine
mammals have very high concentrations of myoglobin in their muscles.
Thus they can store a lot of oxygen in their muscles.

6. What do I do before a deep dive to avoid “the bends” (avoid having nitrogen bubbles
form in the blood)?
The sperm whale exhales before a deep dive. Remember that air is 78%
nitrogen. This nitrogen gas can enter the blood and be forced into solution
by high pressure. When the animal swims back to the surface the reduced
pressure can cause nitrogen bubbles to form in the blood.
If the animal exhales before a dive most of the nitrogen in the lungs is exhaled.
In addition, whales have collapsible rib cages. As the pressure increases
during a dive, the ribs collapse, forcing any remaining air out of the alveoli.

7. Identify structures
1 and 2.
1. Capillaries
Alveoli (the air sacs of the lung) – Note that oxygen diffuses from the
alveoli into the capillaries that surround
them.

8. What are the functions of capillaries?
Capillaries are the sites of gas exchange. This is where oxygen leaves the blood
and enters the tissues.
Explain this picture.
This picture is a drawing of a capillary. Notice that this microscopic blood vessel
is one cell thick and is composed of thin flat cells. Also notice the oxygen is
leaving the blood and diffusing through the wall of the capillary into the tissues.