There are three ways that amphibians survive the winter: (1) sleeping at the bottom of ponds, (2) sleeping underground, and (3) freeze tolerance. Some frogs like bullfrogs and green frogs sleep at the bottom of ponds where they can absorb oxygen through their skin without needing food. Toads dig holes underground below the frost line. Wood frogs, grey tree frogs, and spring peepers produce glucose outside their cells, lowering the freezing point so water moves out of their cells, allowing them to freeze without damage and thaw in spring.

1. Over Wintering
By Mr. “Freeze Me” Chapman

2. Over wintering
 Amphibians have developed many different
ways to survive the harsh winters.
 3 different types:
 1. Sleep at bottom of ponds
 2. Sleep underground
 3. Freeze Tolerance

3. Bottom of Ponds
 When weather becomes
cold, frogs like
bullfrogs and green
frogs find a pond.
 They will move to the
bottom of the pond and
sleep/lay at the bottom
until spring.

4. How do they survive?
 The water is cold and will hold lots of oxygen,
so the frog can absorb oxygen through skin.
 Frogs are cold blooded, so their body is cold
and barely functioning, so they do not need
any food.
 Frogs will lay at the bottom of the pond, until
the water warms up and wakes them up.

5. Sleeping Underground
 Some amphibians like toads use their back feet
to dig a hole in the ground to sleep in all
winter.
 They must make sure they bury themselves
below the frost line, or the will freeze and die.

6. How do they survive?
 The air is cold and hold lots of oxygen and the
toad absorbs oxygen out of the air.
 Same as before, they are ectothermic and do
not need any food. Their body is barely
functioning.
 They will stay in the ground until their body
warms up to a specific temperature.

7. Freeze like a Ice Cube
 This is done by wood frogs, grey tree frogs,
and spring peepers.
 These frogs find a good place to hide like
under leaves or bark on trees.
 Then they lay and wait for the winter.

9. Freeze Tolerance
 When the temperature starts to fall these frogs
start to produce glucose (sugar) in their bodies.
 The important thing is that the glucose is not
produced inside the cells, but outside of the
cells in the spaces in between the cells.
 This cause osmosis, which means the majority
of the water in the cells moves out of the cells
and into the area in between the cells.

11. Freeze Tolerance
 The Glucose does 2 things:
 1. lowers the freezing temperature at which the
water would freeze (32 to 16).
 2. Removes water from cells.
 The skin of the frog can withstand the
expanding water and will not burst.

13. Freeze Tolerance
 As the weather warms up the ice inside the
frog will melt and the water will move back
into the cells.
 Then the frog will then wake up and will go
and search for food.