Herpetology

Herpetology deals with the identification and life science of different specimens of amphibians and reptiles. The official taxonomy list used for this event is posted on http://www.soinc.org/events/herpetology. In this article, I will mainly deal with the life science portion of this event, as identification is a skill that is best learned on your own. While field guides may help with learning how to ID specimens, different techniques for ID and different studying methods will work for different people.

Introduction to Herpetology

Amphibians VS Reptiles

While most amphibians are tied to water throughout their lives, reptiles of many species generally entirely terrestrial. The adaptational differences of each represent this difference.

	Amphibian	Reptile
Eggs	Moist and spongy exterior	Tough outer shell
Skin	Moist glandular skin	Keratinized, rough skin/scales
Reproduction	External generally	Internal generally
Origin	Lobe-finned fishes	Amphibians
Feet	Often webbed, without claws	Clawed
Respiration	Lungs, skin, and/or gills	Lungs, skin in rare cases.

Internal Anatomy

Circulatory System: consists of two loops.

• Pulmonary loop - from heart to lungs and back
• Systemic loop - from heart to body tissues and back

Hearts in all herps other than crocodiles consists of two atria and one ventricle somewhat divided by a septum. Contraction of heart keeps oxygenated and deoxygenated blood seperate even though ventricle isn't completely divided. n crocodiles, two atria and ventricles exist.

There are two main ways in which adult amphibians respire:

• Pulmonary respiration - breathing through lung by positive-pressure breathing
• Cutaneous respiration - respiration through the skin

Nervous System: brain is similarly sized (relatively) in amphibians and reptiles.

In reptiles, the cerebrum (used for controlling behavior) is larger than amphibians. Optic lobes are also large, due to the fact that most reptiles rely on sight for hunting. Some reptiles and amphibians have nictitating membrane which is a transparent,movable membrane that covers the eyes allowing them to see with their 'eyelids' closed.

Hearing is also important. Sound waves heat the tympanum and then are transferred to the inner ear through the columella. Snakes lack a tympanum and best hear low frequency sounds. They detect these ground vibrations which are transferred to columella by the bones of jaw.

The Jacobson's organ is an extra sense organ in the roof of the mouth of reptiles. This organ is used to detect scents in the air. Reptiles use their forked tongue to gather chemicals from the environment and transfer it to the back of their mouth. These scent chemicals are then analyzed by the brain to find prey.

Another 'seventh' sense is present in some rattle snakes. A heat-sensitive pit beneath eyes and used to find direction and distance to warm prey or other objects.

Reproduction

Fertilization - the joining of egg and sperm

• Internal Fertilization - fertilized within female's reproductive tract
• External Fertilizaqion - fertilized outside body

Reptilian Patterns of Reproduction - division of reproduction methods by how long eggs stay within female and in how eggs are provided with nutrition

• Oviparity - female's tract encloses egg in tough shell which is then deposited
• Ovovivoparity - eggs retained in female's body before being either laid shortly before hatching or hatching within body
• Viviparity - shell is not formed around egg and young mature in female's body; nutrients often delevered by placenta

Behavior

Many behavioral aspects of reptiles and amphibians are due to their thermoregulation strategies. Each of these species are ectotherms (cold-blooded and gaining heat from environment rather than metabolism). This energy saving strategy leads to several behavioral adaptations.

• Activity - Many ectotherms have optimum temperatures of function (due to the optimum temperatures of enzymes), this results in many organisms in cooler habitats being most active in midday and many organisms in desert habitats to be more nocturnal. The other pros and cons of diurnal/nocturnal are listed below.

Other reasons to be diurnal include easier sight and communication as well as more common prey in some habitats. Reasons to be nocturnal include less competition for food and fewer predators in some habitats.

• Dormancy - During cold or dry seasons, some organisms 'hibernate' in order to retain energy.

Other aspects of behavior good for review are mating rituals, how they interact with other organisms (aggressive or passive), and how they obtain food.

Conservation

Populations of various reptiles have diminished for several reasons. First of all is their (or their eggs) use as food in many cultures. (Snapping Turtle soup is actually quite tasty.) "Rattlesnake roundups" have occured in some states as recreational activities. Snakes are gathered to be killed by visitors who do so in belief that killing snakes protect public. Every year in Sweetwater, Texas, about 1% of the entire rattlesnake population of Texas is slaughtered. Some attendees claim that this is justified due to the fact that they collect venom, however the venom is useless for most any research as it is not collected in a sterile environment. Some are also gathered for use as folk medicine. Snake venom has use in medical research. Habitat destruction is also hurting various populations.

Amphibian populations have been mysteriously declining for several years. Ther are several proposed reasons for this decrease. Some believe thinning of the ozone layer increases the amount of UV B radiation that reaches sensative eggs, embryos, and larvae causing them to die. Herbicides, pesticides, and fertlizers also have killed amphibians when interfering with their natural hormones. Habitat destruction and disease have also lead to a large amount of decrease in population.

Helpful Hints

1) If they allow a field guide, make your own, and know where everything in it is.

2) Be able to identify quickly, you should be able to do most if not all identification without resources.

3) Do not rely on your field guide, memorize as much as you can.

4)Make flashcards or online quizzes to study.

Reference

• Audubon guide
• Peterson guide

Previous Winners

	Team
2008	Harriton High School

Links

• Amphibians and Reptiles http://edtech.kennesaw.edu/web/reptiles.html
• Amphibians http://worms.zoology.wisc.edu/frogs/mainmenu.html
• Frog Call Quiz http://www.pwrc.usgs.gov/frogquiz/
• Detailed Information on Limited Taxa http://tolweb.org/tree/
• Versatile Resource http://cnah.org/
• Good For Identification Quizes http://www.californiaherps.com/index.html
• Frogs http://www.exploratorium.edu/frogs/
• Frog Links http://www.pca.state.mn.us/kids/froglinks.html
• More about frogs.. http://www.awesomelibrary.org/Classroom/Science/Biology/Amphibians.html
• Frogs - color pictures & sounds http://www.naturesound.com/frogs/frogs.html
• New York Coaches Conference http://newyorkscioly.org/SOPages/Events/Amphibians-Herpetology.html