Reptilia

Author: Jenny Schorgl
__**EXAMPLES**__: >> //Nile Crocodile// >> //Florida Box Turtle// >> //Central Bearded Dragon (left) Coast Garter Snake (right)// >> >> //Male tuatara//
 * Reptiles are classified into 4 different orders:
 * **Crocodilia** (crocodiles & alligators) - 23 species
 * **Testudines** (turtles, tortoises) - 300 species
 * **Squamata** (lizards, snakes, worm lizards) - 7,900 species
 * **Sphenodontia** (tuataras from New Zealand) - 2 species

__**HABITAT**__:
 * most modern reptiles inhabit every continent except Antarctica
 * deserts, forests, freshwater, wetlands, mangroves and open ocean
 * mostly near water sources (freshwater)

__**TYPE OF COELOM:**__
 * reptiles are coelomates - coelom is lined with mesoderm


 * __ENDOSKELETON or EXOSKELETON__:**
 * reptiles contain endoskeletons, even though they have keratinzed dry skin
 * reptilian skin is covered in a horny/scaly epidermis made of protein (keratin) - which makes it watertight and helps them live on dry land
 * tortoise has endoskeleton and exoskeleton both


 * __TYPE OF NERVOUS SYSTEM__:**
 * The reptilian nervous system contains the same basic part of the amphibian brain but the reptile cerebrum and cerebellum are slightly larger; advanced and centralized nervous system
 * consists of a cerebrum, cerebellum, brain, a spinal nerve cord, 12 pairs of cranial nerves running from the brain/spinal cord, sense organs and eyes
 * Most typical sense organs are well developed with certain exceptions (snake's lack of external ears)
 * There are twelve pairs of cranial nerves
 * Due to their short cochlea, reptiles use electrical tuning to expand their range of audible frequencies
 * Reptiles are generally considered less intelligent than mammals and birds because the size of their brain relative to their body is much less than that of mammals
 * Larger lizards have more complex brain development but are known to exhibit complex behavior (cooperation)
 * Crocodiles have a relatively larger brain and show a fairly complex social structure

__**FEEDER**__:
 * reptile ancestors were carnivorous; some reptile species are omnivorous or herbivorous
 * insects are the "basic food" for reptiles - insects constitute small meals of highly concentrated energy
 * feeding adaptations fall into 3 basic categories
 * equipment for herbivorous diet
 * adaptations making possible the swallowing of big objects
 * equipment and behavior adapted to the taking of some one special kind of food (eggs)

__**SYMMETRY**__:
 * reptiles are complex animals that demonstrate a bilateral symmetry
 * reptiles have scaly skin and feet with claws on their 5 toes, skulls with a single occipital condyle, lungs instead of gills for respiration and 3 or 4 chambered heart

__**REPRODUCTION**__:
 * reptiles reproduce sexually
 * fertilization occurs inside the female, rather than the outside as it does in most amphibians
 * fertilized in her body by the male - male and female press their cloacas together while the male excretes his sperm into the female's body
 * after internal fertilization, the female lays an amniotic egg without passing through a larval state - eggs are covered with a leathery/calcium-based shell to protect it in the wilds -
 * asexual reproduction (parthenogenesis) has been identified in 6 lizard families and 1 snake family
 * some reptiles exhibit temperature-dependent sex determination (TDSD) - meaning that the incubation temperature determines whether an egg hatches as a male or female
 * most common in turtles and crocodiles; also occurs in lizards and tuataras

__**CIRCULATORY SYSTEM**__:
 * reptiles have a heart with two chambers
 * unable to sustain rapid activity in circulatory system though

__**ENDOTHERMIC or EXOTHERMIC**__.
 * most reptiles are cold-blooded and are therefore exothermic - can generate their own internal heat through external absorption of heat
 * endothermic creatures must use calories from food to regulate body temperature
 * some cases of endothermic reptiles exist, however (some dinosaurs)

__**SEGMENTATION**__:
 * reptiles are non-segmented

__**WORKS CITED**__: Council-Garcia, Cara Lea. "Deuterostomes." UNM Biology Department Home Page. University of New Mexico, 2002. Web. 26 Mar. 2011. .

Khatoon, Janat. "Eating Habits of Reptiles (Part 1)." Suite101.com: Online Magazine and Writers' Network. 24 Dec. 2000. Web. 26 Mar. 2011. .

Klappenbach, Laura. "Reptiles - Facts, Classification and Evolution of Reptiles." Animals Wildlife - Animal Facts, Animal Pictures, Habitat Facts, Evolution and Zoology. Web. 26 Mar. 2011. .

Mader, Sylvia S. "Biology." Ed. Thomas C. Lyon. New York City: McGraw Hill, 2007. Print. "REPTILE." Monroe County Women's Disability Network. Web. 26 Mar. 2011. .

"Reptile." Wikipedia, the Free Encyclopedia. Web. 26 Mar. 2011. .