Taking in oxygen, expelling CO2


Breathe through moist skin
Gases move through by diffusion
Oxygen diffuses into the muscle cells



Gills are surrounded by blood vessels and
have a lot of surface area for removing
oxygen dissolved in water
Water passes over gills and oxygen diffuses
into vessels
Oxygen is carried to muscles through vessels


Juveniles have gills
Adults develop lungs
◦ No diaphragm
◦ Air has to be pushed in and
out

Adults can also breathe
through moist skin by
diffusion



Some aquatic reptiles can
breathe through skin
Air is sucked in by expansion
of ribcage
Crocodiles have a diaphragm



High need for oxygen
Air sacs allow for one-way air flow
Fresh air flows through lungs; stale air
doesn’t
http://www.smm.org/heart/lungs/breathing.htm


Inhalation: diaphragm
lowers, chest volume
increases, chest
pressure decreases, air
rushes in
Exhalation: opposite
happens
Transports materials throughout body
(gases, nutrients, wastes, etc.)


Has blood vessels (closed circulation)
Has 5 pumping vessels that act as hearts



Heart
No loop of blood vessels (open circulatory
system)
Hemolymph (no blood)



2-chambered heart
One loop of blood
vessels
Good enough for life in
water


Juvenile: 2-chambered
heart
Adult: 3-chambered
heart

3-chambered heart (except for crocs)



4-chambered heart (most efficient)
2 loops of blood vessels
Keeps oxygen-rich blood separate from
oxygen-poor blood

Oxygen is taken in by
respiratory system,
diffuses into blood
vessels, gets taken to
rest of body.