Things students should notice:
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Fish:
o
o
o
o
o
Frog:
o
o
o
o
o
o
o
Birds:
o
o
o
o
o
o
o
o
o
Swim bladder, used for depth control
Two chambered heart – one atrium and one ventricle
Gills rather than lungs
Lateral line senses water currents and pressure
Has a urinary bladder
Three chambered heart (two atria, one from lungs, one from body, blood mixes in
ventricle and mixed blood is pumped out to the body)
Gas exchange occurs through the lungs and through the skin
Specialized tongue
Has urinary bladder
Has no ribs, has legs and feet
Eye can be pulled into its socket
No external ear – ear drum (tympanic membrane is exposed)
Wings
Feathers are modified scales
Light hollow bones
Beak
Four chambered heart separates oxygenated and de-oxygenated blood
No teeth, crop stores food, gizzard does mechanical breakdown
No urinary bladder
No diaphragm
Bird gets oxygen when inhaling and exhaling. Bird inhales air into lungs and air
sacs. When exhaling, fresh air goes from air sacs into lungs. Oxygen poor air and
oxygen rich air don’t mix.
Rat:
o Four chambered heart where oxygen rich and poor blood don’t mix
o Urinary bladder
o Lungs
o Limbs for living on land
Snake:
o No external ear, sense vibrations through the ground
o Tongue is used for smell, brings small particles into Jacobson’s organ
o No eyelid
o Some snakes have organs for sensing temperature changes
o No limbs
o Many, many vertebrae and ribs
o Head bones connected by ligaments allowing lots of stretch
o Teeth grow back when lost. Teeth are different in different kinds of snakes –
some venomous, some two rows of upper teeth
o No diaphragm
o Long right lung. Lower half is an air sac that regulates pressure in body.
o Short largely useless left lung
o Three chambered heart, two atria, one ventricle
o No urinary bladder