Class Reptilia

Class Amphibia

CHORDATALatin term for “chord”

http://universe-review.ca/R10-33-anatomy.htm#amphibians

Chordata- Urochordata, Cephlachordata, Agnatha, Chondrichhyes,Osteichhyes, Aves, Mammalia

The best classes: Reptilia and Amphibia

Amphibia– Latin meaning “two lives” [water and land based]

Ex. Salamanders, frogs, toads

http://webpages.charter.net/teefile/biognomen/photo/Amphibia.jpeg

http://news.siu.edu/news/May05/images/salamander.jpg

http://www.lemmykoopa.com/lk19/2_5.jpg

http://library.thinkquest.org/TQ0312042/Images/American%20Toad.jpg

• Amphibians were the first vertebrates on land

• Early amphibians- lobe-finned fishes with lings, freshwater [b/c of drought] paired appendages to walk on land

Types of Amphibians

Urodeles- walk with lateral bending of the body i.e. salamanders

Anurans- use legs for hopping i.e. toads/frogs

Apodans- burrowing, legless, nearly blind, wormlike i.e. snake-type animals

Amphibia

Gas exchange- integuments (outer covering) allow gas exchange through skin; Adults generally respire using lungs and through moist skin

Skeletal- bony skeleton

Reproduction- External fertilization requires aquatic environment 

General Characteristics

Of Phylum Chordata• notochord • dorsal hollow nerve chord • pharynx slits • muscular postanal tail

Body cavity-- coelom present; heart inside

Symmetry-- bilateral

Nervous– Brain reguates digestion and circulation; muscular coordination

Circulatory system– 3-chamber <3; mixed blood in single ventricle; pulmonary veins; only organ in coelom

Sensory– smell: two holes and olfactory lobes; crude eye: cannot change focus, eyelid; exposed ear

Digestion- mouth, weak teeth, sticky tongue to capture prey, esophagus, stomach, intestines, liver, pancreas, gall bladder

Excretory– liquid pass kidney to bladder; liquid and solid exit through cloaca. Urea gets rid of nitrogenous waste

Musco-skeletal– walking legs w/ <5 toes, flat skull, backbone, “shoulders,” leg bones

• Class Reptilia: (Latin repere, "to creep").

• The 3 largest and most diverse orders:– Crocodilia (alligators & crocodiles): 23

species – Squamata (lizards & snakes): approximately

7,600 species – Chelonia (turtles): approximately 300 species

Major Groupings

Tuatarahttp://

members.tripod.com/NZPhoto/animal/

tuatara.htm

Crocodilehttp://www-

biol.paisley.ac.uk/courses/Tatner/biomedia/subunits/

order57.htm

Zebra-tailed lizardhttp://

en.wikipedia.org/wiki/Lizard

Green Sea Turtlehttp://www.nmfs.noaa.gov/pr/

species/turtles/green.html

San Diego Alligator Lizard

http://www.yosemite.ca.us/library/reptiles/images/thumbnail/lizards_22.jpg

Gecko-Reptile; this is some kind of local reptile…

or something

Coleonyx variegatus abbotti

http://www.werc.usgs.gov/fieldguide/images/covajuv.jpg

Baby San Diego Gopher Snake

http://www.gregcooper.net/reptiles/sandiegogopher/gallery/SDG009a.jpg

Anatomy• Extraembryonic membranes:

– from embryonic tissue layers– Consist of:

• amnion (for protection), • yolk sac (expands over yolk, where nutrients are

stored)• allantois (disposal sac & functions as respiratory

organ)• chorion (functions as respiratory organ)

– involved in gas exchange, waste storage, and nutrient transfer from egg to embryo

Amniotes!

amniote = a reptile whose eggs contain specialized membranes that allow them to develop out of water

– The first amniote reptile evolved from an amphibian about 300 million years ago.

salamanders = amphibians; aren't amniotes; eggs lack the shell.

reptiles, birds, and mammals are amniotes

• Amniotic egg:– Enclosed in a waterproof shell and permitted

vertebrates to complete their life cycle– The shell retains water and can therefore be

laid in a dry place

The Amniotic Egg

http://io.uwinnipeg.ca/~simmons/16cm05/1116/chordate.htm

Physiology• Body Cavity: coelom present

• Body Symmetry: bilateral

• Circulatory System:

– Ectotherms – absorb external heat rather than generating their own (“cold blooded”)

– Exchange of oxygenated and deoxygenated blood between the ventricles in all reptiles but the crocodile

• Digestive System: All reptiles except snakes have a cecum, at the beginning of the large intestine; gall bladder present; caudal abdomen stores fat.

• Gas Exchange: Reptiles have well-developed lungs enclosed within a protective rib cage.

• Locomotion/Musculature: Most reptiles have legs with usually five clawed fingers or toes

• Excretory System: – Crocodilians, snakes and some lizards

do not have a urinary bladder– those with a bladder, have it connected

to the cloaca by a short urethra.

• Skeletal Type:– Vestigial pelvic and limb bones in

primitive snakes are evidence that snakes evolved from reptiles with legs

– Scales contain the protein keratin which waterproof the skin

• Sensory Structure/ Features:

– Snakes have acute chemical sensors & are sensitive to ground vibrations

– Heat-detecting organs between the eyes and nostrics of pit vipers & rattlesnakes are sensitive to temperature changes

• Nervous System: well developed especially within the brain and with regard to optic nerves; visual sensory system

• Reproduction: Some species lay shelled amniotic eggs and fertilization is internal

Reptiles vs. Amphibians

• Amphibians have shell-less eggs, while reptiles have amniotic eggs that have a shell that retains water and can be laid in a dry place

• Reptiles have scales containing the protein keratin, which waterproof the skin to prevent dehydration in dry air

Quiz

Why do you think reptiles need fewer calories than mammals?

a. Ectothermic

b. Waterproof scales

c. Amniotic egg

d. More effecient respiratory system

A

What is true of amphibians?

a. Amphibian's blood is blue-colored

b. They have a 3-chambered heart

c. They only respirate through skin

d. Amphibians are green… always

B

What are not amniotes?

a. Amphibia

b. Reptilia

c. Aves

d. mammalia

A

What is not distinct about reptiles?a. reptiles have amniotic eggs that have a shell that retains water and can be laid in a dry placeb. Reptiles have scales containing the protein keratinc. They have waterproof skin to prevent dehydration in dry aird. They like cheetosE. All of the above are true about reptiles

The answer is E, [answer d gets ½ credit]

Now for some cool stuff…

http://www.reptileallsorts.com/snakefood.htm

Gecko Hatching: http://www.reptileallsorts.com/reptil

emovies.htmOdd

deformities & New Species

http://news.bbc.co.uk/1/hi/sci/tech/848629.stm

http://news.bbc.co.uk/1/hi/sci/tech/848629.stm