Ch. 41 - ReptilesUnlike amphibians, reptiles don’t have Unlike amphibians, reptiles don’t have to return to the water to reproduce. to return to the water to reproduce. They were the first vertebrates to live They were the first vertebrates to live on land during their whole life cycle.on land during their whole life cycle.

Reptiles evolved a new reproductive Reptiles evolved a new reproductive structure that allowed them to structure that allowed them to reproduce on land. What is this reproduce on land. What is this structure?structure?

Amniote eggAmniote egg

Amniote Egg ( 5 parts)1. Porous shell – protects & prevents water 1. Porous shell – protects & prevents water loss.loss.

2. Amnion – salty fluid that allows the 2. Amnion – salty fluid that allows the embryo to float.embryo to float.

3. Allantois – excretes nitrogenous waste 3. Allantois – excretes nitrogenous waste from the embryofrom the embryo

4. Chorion – lines the outer shell. Diffuses 4. Chorion – lines the outer shell. Diffuses carbon dioxide & oxygen through the shell.carbon dioxide & oxygen through the shell.

5. Yolk sac – supplies food for the embryo. 5. Yolk sac – supplies food for the embryo.

Characteristics of Reptiles1. Dry body covering (some with scales)1. Dry body covering (some with scales)

Made of keratin to prevent water loss.Made of keratin to prevent water loss.

2. Lungs2. Lungs

3. 3-chambered heart with the ventricle 3. 3-chambered heart with the ventricle partially divided. (alligators have 4)partially divided. (alligators have 4)

4. Ectotherms – body temperature is 4. Ectotherms – body temperature is influenced by the environment.influenced by the environment.

5. Limbs, if present, have toes with claws.5. Limbs, if present, have toes with claws.

6. Internal Fertilization (big advantage)6. Internal Fertilization (big advantage)

Origin of ReptilesReptiles where thought to of arose Reptiles where thought to of arose from the cotylosaurs. Pg. 820from the cotylosaurs. Pg. 820

Mesozoic era is known as the Age of Mesozoic era is known as the Age of Reptiles.Reptiles.

When were the dinosaurs thought to When were the dinosaurs thought to have become extinct?have become extinct?

Cretaceous PeriodCretaceous Period

Dinosaur means “terrible lizard”Dinosaur means “terrible lizard”

Reptile Orders Cl.: Reptilia1. Rhynochocephalia1. Rhynochocephalia

Tuatara – the only species in Tuatara – the only species in this orderthis order

•Only in New ZealandOnly in New Zealand

•Parietal eye – “3Parietal eye – “3rdrd eye” on the eye” on the top of their headtop of their head

2. Chelonia 2. Chelonia Turtles Turtles

Dorsal shell is called the Dorsal shell is called the carapacecarapace

Ventral shell is called the Ventral shell is called the plastronplastron

A A bridgebridge connects the two. connects the two.

Turtles are protected very well with Turtles are protected very well with their shell.their shell.

Snapping turtles are one of the more Snapping turtles are one of the more aggressive turtles. They have a aggressive turtles. They have a worm-like tongue to attract fish.worm-like tongue to attract fish.

3. Crocodilia3. CrocodiliaCrocodiles & alligatorsCrocodiles & alligatorsCaimans (short & wide snout) & gavials Caimans (short & wide snout) & gavials (long & narrow snout).(long & narrow snout).The only living relatives of the The only living relatives of the dinosaurs.dinosaurs.Have you ever wondered why an Have you ever wondered why an alligator or crocodile doesn’t swallow a alligator or crocodile doesn’t swallow a lot of water when it has its mouth open?lot of water when it has its mouth open?It has a glottis that prevents this.It has a glottis that prevents this.Have you ever heard of the “Crocodile Have you ever heard of the “Crocodile Man”?Man”?

4. Squamata 4. Squamata Largest Order Largest OrderLizards & SnakesLizards & SnakesThere are only 2 poisonous lizards There are only 2 poisonous lizards • 1. Gila Monster – S.W. U.S. 1. Gila Monster – S.W. U.S.

Has grooved teeth with venom & Has grooved teeth with venom & shakes its head to release the shakes its head to release the venom.venom.

• 2. Beaded Lizard – Western Mexico2. Beaded Lizard – Western MexicoName as many lizards a possibleName as many lizards a possible• Iguanas, horned toads, chameleons, Iguanas, horned toads, chameleons,

skinks, & geckosskinks, & geckos

Horned lizards or horny toads live Horned lizards or horny toads live around here. They have armored around here. They have armored spikes covering them and when spikes covering them and when disturbed they his and squirt blood disturbed they his and squirt blood out their eyelids.out their eyelids.Skinks and geckos have the ability Skinks and geckos have the ability to lose their tails and regenerate a to lose their tails and regenerate a new one .new one .The term for this is The term for this is autotomyautotomy..

SnakesNo limbs and to external earsNo limbs and to external ears

There is evidence for believing that There is evidence for believing that snakes once had legs. Some pythons snakes once had legs. Some pythons & boas still have vestigial hind legs.& boas still have vestigial hind legs.

How many of you fear snakes?How many of you fear snakes?

How many of you fear rattlesnakes?How many of you fear rattlesnakes?

A graduate study was done on the A graduate study was done on the human perception of snakes.human perception of snakes.

2,800 species of snakes, only 300 species 2,800 species of snakes, only 300 species are poisonous or dangerous.are poisonous or dangerous.

What are the poisonous snakes of Kansas?What are the poisonous snakes of Kansas?

Prairie rattlesnake, pigmy rattlesnake, Prairie rattlesnake, pigmy rattlesnake, cottonmouth, western diamondback cottonmouth, western diamondback rattlesnake, timber rattlesnake, rattlesnake, timber rattlesnake, copperhead.copperhead.

What is the largest snake in the world?What is the largest snake in the world?

Anaconda (33 ft.), smallest is about 4 in.Anaconda (33 ft.), smallest is about 4 in.

What does molting mean?What does molting mean?

Snakes have between 100 – 400 vertebraeSnakes have between 100 – 400 vertebrae

3 ways of movement in snakes1. Lateral Undulation – most common method for crawling or swimming.

Draw

2. Rectilinear or caterpillar movement – is the contract and condense of the muscles.

Draw

3. Sidewinding – mostly used by???

Draw

Snake PartsNictitating membrane to cover their eyes.

Forked tongue that is used for the great sense of smell.

The branches of their tongue pick up particles in the air, then slide over top their Jacobson’s organs at the roof of their mouth, which are sensitive to odors.

All snakes are carnivores

A snake’s jaw can unhinge to engulf their prey.

What are the 2 methods snakes use to kill its prey?

3 methods of injecting venom:

1. Vipers – large front retracting fangs (hypodermic)

Ex. Rattlesnake, copperheads, cottonmouth

2. Elapids – small front fixed fangs (hypodermic)

Ex. Cobra & coral snakes

3. Rear-fanged snakes – bite the prey & use grooved back teeth to inject the venom.

Twig snakes & boom slang snakes of Africa

2 types of poisons in venom1. Neurotoxins – affects the nervous system• Can’t breath or swallow

2. Hemotoxins – affects the circulatory system• Destroys the blood vessels (rupture)

Circulatory System

Two paths of blood in most terrestrial vertebrates

Pulmonary Path – deoxygenated blood from heart to lungs; oxygenated blood back to heart from lungs

Systemic Path – transport of oxygenated blood to body systems from the heart returning as oxygen is used up.

Respiratory SystemPulmonary respiration – lungs lined with air sacs called alveoli. Sacs used to increase surface area for more absorption of oxygen.

ThermoregulationEctotherm – warms its body by absorbing heat from its surroundings. This is why most lizards and snakes are found in warm climates.

ReproductionInternal FertilizationOviparous – lays the eggs outside her body.Ovoviparous – eggs are hatched inside her body. Not nourishedViviparous – bear live young that are nourished inside her body until they are developed.A snake breaks through the shell by using a egg tooth, which is lost after it breaks through the egg.