How Herps Survive the Winter

Jennifer Holgate and Lindsey Whitebread

What is Herpetofauna (Herps)?

Herpetology

The study of amphibians and reptiles

Reptiles

Any of various cold-blooded, usually egg-laying vertebrates of the class reptilia, such as a snake, lizard, crocodile, turtle, or dinosaur, having an external covering of scales or horny plates and breathing by means of lungs.

Amphibians

Any cold-blooded vertebrate of the class amphibia, comprising frogs and toads, newts and salamanders, and caecilians, the larvae being typically aquatic, breathing by gills, and the adults being typically semiterestrial, breathing by lungs and through the moist, glandular skin.

Reptiles and Amphibians

Painted turtle

Garter snakeSnapping Turtle

NewtBull Frog

Peeper

Herps are Ectothermic

• Ecto means “from outside”

• “Cold-blooded”

• Heat must be absorbed through environment

Adaptations for Survival

Hibernation– Freeze Tolerance– Freeze Avoidance

MigrationShivering

Where do they go?

• Shorter days and colder temperatures give herps the urge to hibernate.

• Many reptiles and amphibians such as turtles and frogs hibernate at the bottoms of lakes and ponds in the mud.

But how do they Breathe?.....

How can they breathe under water?

Amphibians are able to breathe through their skin to obtain oxygen.

Turtles use cloacal breathing, they pump water through their system while absorbing oxygen from the water.

Some turtles remain active and can be seen swimming under the ice. Very cold temperatures may drive them to burrow into the mud.

If the pond or lake is frozen over and the oxygen runs low, herps can die.

Freeze Tolerance“Supercool”- lowering the body temperature below 0°C without freezing body fluids.

DO NOT TRY THIS AT HOME

•Frozen wood frog

Freeze Tolerance

Gradual freezing of extracellular fluid

Glucose- “Amphibian Anti-freeze”

The Frozen Frog1. Amphibians crawl under logs and litter on the

forest floor.2. Glucose levels increase when body

temperature drops so low that ice begins to form in the animal.

3. Glycogen from the liver is rapidly transformed into glucose and distributed throughout the bloodstream.

4. Blood glucose increases 200x in 8 hours5. Heart beat doubles within one hour of ice

nucleation – the induction of ice formation around any small particle that may serve as a nucleus for crystal growth.

The Frozen Frog

6. The body temperature rises 2°C.

7. After 20 hours of ice nucleation, the body has an ice content of 60 to 65% and the heart stops beating, the frog stops breathing.

8. Survives by anaerobic metabolism, energy reserves and the glucose in its body.

Frogs can’t survive temperatures below -7°C and so, good snow cover is very important.

Rising from the “frozen”9. Once temperatures rise the frog begins

thawing.10. Within an hour after thawing, the heart

resumes beating, and six hours later, at a temperature of only 5°C, heart rate may be back to normal.

Herps cannot stand direct exposure to frost. It can be fatal.

Freeze Avoidance

• Snakes burrow into holes in the ground and hibernate where the temperature may be a few degrees warmer.

• Snake Hibernaculum- large communal dens (tree roots, cliffs, rock piles, sewers, foundations, animal burrows, rock outcrops, sinkholes.) Hundreds of snakes gather together. Temperature never drops below 3-4°C. (37-39°F)

Freeze Avoidence

• Garter snake Hibernaculum

Shivering

Snakes and other reptiles will “shiver” like people do in order to help to produce body heat.

Migration

Sea turtles will follow currents and migrate to warmer waters.

THE END