Biology Week 22- Reptiles

Day 1 | Day 2 | Day 3 | Lab | Weekly quiz

Reptile Alveoli Septum Chelonia Shell Carapace Plastron Turtle Terrapin Tortoise	Squamata Venom Hemotoxin Neurotoxin Pit viper Crocodilia Alligator Crocodile Caiman Gavial	Amniote egg Amnion Yolk sac Allantosis Chorion Ectothermic Endothermic Oviparous Ovoviviparous Viviparous

The Reptiles

What is the purpose of the organ for which "pit vipers" are named?

See where reptiles fit into Earth's history.

Major orders of reptiles:

Chelonia (Testudines)

These animals are generally recognized by their having a shell. While shells within the group are different, they are all an extension of the vertebrae. The dorsal shell of Chelonians is known as the carapace, while the lower shell is the plastron.

The term turtleis often used for any of the animals with a shell.

Turtles		Turtles are marine animals whose limbs are "flippers". They are totally adapted to aquatic life and leave the water only to lay their eggs.
Terrapins		Terrapins are semi-aquatic animals, equally at home in the water or on land. Their feet have webbed toes for swimming. Their shell has a low profile.
Tortoises		Tortoises have "stumpy" legs. They are terrestrial animals and poor swimmers who have been known to drown in deep water. Their shell has a high profile.

Squamata

Lizards - always have eye-lids and external ear openings.
Oklahoma is home to the glass lizard, a lizard without legs.

Snakes - never have eye-lids or external ear openings.

Venomous snakes can produce two types of toxins:
Hemotoxins - venom proteins that destroy red blood cells and disrupt blood clotting.
Neurotoxins - venom proteins that disrupt nerve transmission.

Snakes should not be killed or captured. Snakes are very useful in controlling rodent and insect pest populations. All venomous snakes in Oklahoma are pit vipers and easily distinguished from other snakes. Pit vipers have a heat sensitive organ located between their nostril and eye. This organ is used to find warm-blooded prey. Most people who are bitten by snakes either do not see the snake before it bites or are trying to kill or catch the snake. Either way, the person has come into the "personal space" of the snake and it is reacting to that intrusion. While the characteristics below are easy for an experienced person to recognize, students should treat all snakes as potentially dangerous and give them space.

Characteristic	Pit Viper	Non-poisonous
Triangle-shaped head Oval head
Flat head Rounded head
Eliptical pupils / Pits Round pupils / no pits

Crocodilia

There are no alligators found in our area, but they have been reported in the extreme southeastern corner of Oklahoma. While the alligator is best known, the American Crocodile is found in southern Florida.

A general identification of these animals can be done by comparing their snouts. The information below is from the Florida Museum of Natural History, which provides details about the Order world-wide.

American Alligator	Black Caiman
American Crocodile	Indian Gavial

Day 1 Assignment - Reptiles
Scoring criteria

1. Explain the statement, "There are no turtles in Arizona".
2. Explain the difference between terrapins and tortoises.
3. Look at the animation at the top of this page. Why would a fish swim right into the mouth?
4. What is the common name and scientific name of the Arizona State Reptile?
5. Study this website to understand snake fangs.
   1. What is the purpose of snake fangs.
   2. Describe two types of snake fangs.
6. Study this website to find out what to do if bitten by a venomous snake.
   1. What is the most important thing you should do if bitten?
   2. What is the most important thing you should not do if bitten?

Day 2

What does the term "cold-blooded" mean?

  (bio lab 225)
The amniote egg:

Amnion - encloses embryonic fluid.
Yolk sac - encloses the yolk.
Allantosis - stores embryo wastes.
Chorion - lines the shell and regulates movement of gases in and out of the shell.

Other important terms:

Ectothermic - body temperature is determined by the environment.
Endothermic - body temperature holds at a constant level.
Oviparous - eggs hatch outside the body of the female.
Ovoviviparous - female carries fertilized eggs inside her body until young hatch.
Viviparous - the developing young is nourished inside the body of the female.

Day 2 Assignment - Reptiles
This assignment must be turned in by the end of class today to receive credit.
Scoring criteria

1. Can gases move through the shell of an amniote egg?
2. Which of the four membranes are found in an amniote egg before it is fertilized?
3. What is the name of the structure that connects the carapace and plastron?
4. Is the animation at the top of today's page a "common snapper" or an "alligator snapper"? Give two characteristics visible in the animation that tell which it is.
5. Give an example of an ovoviviparous animal.
6. Go to Zoology Class to find out more about snake venom.
   1. Describe the action of each of the four main destructive chemicals in snake venom.
   2. How are the venoms of Oklahoma snakes different?

Day 3

Do snakes have eyelids?

Herpetologist

Day 3 Assignment - Reptiles This assignment must be turned in by the beginning of class tomorrow to receive credit. Choose one (1) of the following essay planning guides. Explain how reptiles are an evolutionary "improvement" over amphibians. Give your ideas about the cause of the abrupt decline of the dinosaurs.

Research Links:

• Search - The Animal Diversity Web
• Search - BIODIDAC, digital biology resources
• Species Identification - Audubon Field Guides Online
• Herp Pictures - Mike's Herpetocultural Homepage
• Herpetology Links - By Melissa Kaplan
• Medical Herpetology - Herpmed
• Box Turtles - Illinois Natural History Survey
• Types of Venomous Snakes - venomous.com
• Rattlesnake Information - International Rattlesnake Museum, Albuquerque, NM
• Timber Rattler - Wisconsin Department of Natural Resources
• Pigmy Rattlesnake - Stetson University
• Cottonmouths - Stetson University
• More About the American Alligator - University of Florida
• Extinctions, By Time Period - Hooper Virtual Paleontological Museum
• Paleontology & Biology - by Michon Scott
• Dinosaur Information - Zoom Dinosaurs
• Dinosaur Illustrations - by David Goldman, Syracuse University

The "pits" on the head of pit vipers is a heat sensitive organ which the snakes use to locate warm-blooded prey.

The body temperature of "cold-blooded" animals is not internally regulated. It goes up and down with their environment.

Like fish, no snakes have eyelids.