Chapter 41Reptiles

Section 2

Characteristics of Reptiles

Differences• What are some differences

between a snake and a turtle?

• What are some differences between a lizard and crocodile?

Circulatory System• Pulmonary loop- carried

deoxygenated blood from the heart to the lungs and returns oxygenated blood to the heart

• Systemic loop- transports oxygenated blood to the tissues of the body and returns deoxygenated blood to the heart

Heart Structure & Function• Lizards, snakes, turtles, tuataras-

two atria & one ventricle- divided by a wall of tissue- septum

• Crocodiles- two atria & two separate ventricles

• Very little blood (good & bad) mixes in reptile hearts

Heart Structure & Function• Pumping blood through lungs requires

energy

• Inactive reptiles do not need a lot of oxygen

• Aquatic reptiles don’t breathe while underwater

• Heart pumps blood to body and reduces circulation in lungs

Respiratory System• Alveoli- lining of the lungs folded

into numerous small sacs

• Large lungs- absorb much oxygen

• Snakes- only use right lung

• Expand ribcage to fill lungs- humans use similar technique

Nervous System• Cerebrum is larger than amphibian-

controls behavior• Optic lobes (control eyesight) also

larger• Eyes are large• Hearing is important- sound waves to

eardrum (tympanum) to columella

Nervous System• Jacobson’s organ- specialized sense

organ located in the roof of mouth- senses odors

• Snakes use tongues to sense environment

• Snakes are able to detect heat from heat-sensitive pits located below each eye

Thermoregulation• Control of body temperature-

thermoregulation

• Ectotherm- warms body by absorbing heat from surroundings

• Endotherm- mammals & birds- rapid metabolism which generates heat to warm body

Thermoregulation• Aquatic ectotherms- keep body

temperature around the same as water

• Terrestrial ectotherms- keep body warmer due to sunlight & basking

• Endotherms- feathers, body fat, hair to retain heat

Thermoregulation• Reptiles need to bask often in order to

raise body temperature• Example: Lizard body temperature

drops at night. In order for lizard to become active, it must bask in the sun.

• Reptiles need to raise body temperatures to digest food

Advantages & Limitations to Ectothermy

• Reptiles- slow metabolism- need little energy & food

• Ectotherms cannot live in cold climates, if climate is cool for a long period of time, reptile will hibernate

Reproduction• Oviparity- female’s reproductive tract

encloses each egg in tough protective shell

• Ovoviviparity- retain eggs within the female’s body (eggs may be laid or may hatch in female body)

• Viviparity- shell does not form around egg & young are retained inside until born

Reproduction• Placenta- nutrients & oxygen are

transferred from mother to embryo

Parental Care• Crocodiles & alligators provide

most parental care of reptiles

• Build nest for young

• Guard against predators

• Carry young in mouth & protect for over a year

REVIEW!!!• Compare thermoregulation in

animals that are endothermic versus thermoregulation in animals that are ectothermic

• Contrast oviparity with viviparity.