Those Scaly Reptiles

Mrs. RedingerPlant & Animal BioBest Class Ever!!!!!

Classification

•Kingdom: Animalia•Phylum: Chordata

– Subphylum : Vertebrates

•Class: Reptilia

4 Orders1) Chelonia – 250 species of turtles

& tortoises2) Crocodilia – 21 species of crocs &

gators3) Squamata – 5,500 species of

snakes & lizards4) Rhynchocephalia – 2 species of

tuaturas

Evolutionary History

• Evolved ~ 300 mya- from amphibians- had sharp teeth, claws, & strong jaws for hunting insects

• 300 different genuses of dinosaurs- adapted to wide range of

environmental conditions- 65 mya = EXTINCT = MASS

EXTINCTION- # 1 hypothesis = ASTEROID- Only the 4 modern Orders of reptiles SURVIVED

Reptilian Traits

Reptilian Traits

1) Dry, scaly, waterproof skin

Reptilian Traits•2) Amniotic egg = shell & yolk

Reptilian Traits

•3) Lungs

Reptilian Traits

4) Ecto/Exotherms

Reptilian Traits

•5) Molt/Shed their skin

Amniotic Egg~ this is strong evidence that 3

groups (Reptiles, Birds, & Some Mammals) come from the same

ancestor

Purpose: nutrients, protection, support, prevents H2O loss,takes in O2 / rids CO2

Amniotic EggAmnion: thin

membrane which encloses embryo & contains floating liquidAmnion

Amniotic Egg

Yolk sac: nutrients & fats

Amniotic Egg

Allantois: store N2 waste & exchanges O2 & CO2

Amniotic Egg

Chorion: protects embryo & its vital parts

Amniotic Egg

Albumen: white – stores protein & H2O for the embryo

Amniotic Egg

Egg Shell: protection, prevents H2O loss, & is tough & leathery

Amniotic Egg

Air Sac/Space: breathe when hatching

Water Tight SkinPurpose:- decreases H2O loss

- protection against wear,tear, & infections

Made up of: keratin – thick protein with lipids to help repel H2O

- same as hair & nails

RespirationPurpose: exchange O2 & CO2

with animal & environmentMade up of:

- Lungs ~ increased surface area-Alveoli ~ air sacs that make up lungs for

increased surface area

Respiration

Mechanics: Diaphragm - rib cage expands

when inhale & contracts when exhale

RespirationVariation in snakes: larger right

lung (½ length of body) ~ small, non-functioning left lung

Excretory

Purpose: to remove nitrogenous waste

Nitrogenous waste: - reptile’s urine is very

concentrated with ammonia

Digestive

Purpose: Break down food into useable molecules

1-way system composed of:- mouth & anus

Circulatory~ more advanced & efficient than

amphibians

2 loop system: Systemic loop:

- heart to body to heart

Pulmonary loop:

- heart to lungs to heart

Number of heart chambers:

Lizards, snakes, turtles: 3 2 A1 V

Crocs, gators: 42 A2 V

partial or full septum

NervousSight: larger eyes better sightHearing: all reptiles except

*SNAKES!*- tympanic

membrane (inner ear)Variation in snakes: use lower jaw to detect vibrations

Smell:Jacobson’s organ: ~ located on roof of mouth

- brings in scents by using tongue

Pits: small openings under eyes that detect heat given off by prey

~ brain = same size as amphibians brain but larger cerebrum & optic lobe

~ all have nares except crocs & gators

Nervous System

Thermoregulation:

Two Types:Ecto/exotherms: cold blooded – use sun to regulate body temperature

Examples: reptiles & amphibians

Thermoregulation:

• Advantages– Require less energy– 1/10 food

Thermoregulation:

• Limitations– Can’t live in cold environment unless they

hibernate – Not very active

Endotherms

- warm blooded- regulate own body temp.

thru metabolismExamples: mammals & birds

Endotherms

• Advantages– Can live anywhere – Lots of energy – Very mobile

Endotherms

• Limitations– Need large quantities of food

Reproduction

3 patterns of reproduction:

Oviparity: most reptiles, all birds, & 3 species of mammals~ shell formed in reproductive tract~ laid outside the body

Reproduction

Ovoviviparity: some reptiles~ shell is retained in female ~ young hatch while inside cloaca

ReproductionViviparity: most mammals

~ female releases egg, internal fertilization~ mom houses, protects, & feeds young via placenta

Modern Reptiles:4 orders and they all share the following

traits:1. Dry, scaly, water tight skin2. Ecto/exothermic ~ low metabolisms3. Amniotic egg with internal fertilization4. Respire through lungs

Order Chelonia:Traits of the order:

1. Beak *NO TEETH*2. Oviparity: lay eggs in sand/soil3. Body covered with 2 shells, pieces called SCUTES

Order Chelonia:

Carapace: - top, dome-like shell- vertebrae of turtle is fused into shell - ribs form off vertebrae

Plastron:- lower, ventral shell- protect internal organs

Turtle Skeleton

4. Body Shapes & Adaptions

Aquatic turtles:~ flat disc-like shaped shell: easier to move in H2O~ webbed feet for swimming

4. Body Shapes & Adaptions

Terrestrial turtles:~ dome-shaped shell~ feet are scaled & clawed

More on Turtles…

Order Crocodililia:

Traits of order:1. Large, heavy armored2. Carnivorous3. Oviparity - lay eggs in nest - mom cares for

young for 1-3 yrs.

Order Squamata:

Traits of order:Lizards: 1. Carnivorous (insects & small mammals) 2. Lower jaw attached loosely to skull 3. Agility, speed, & camo to elude predators 4. Actually detach & regrow tail in order to escape

Snakes:

1. No legs

2. Very long backbone with a pair of ribs off each vertebrae

3. 100-400 vertebrae

4. Can pop lower jaw in or out to eat prey whole

5. 1000’s of muscles for movement

Snakes:Constriction:

~ coil around prey~ each time prey breathes, snake increases its tension~ suffocates to death

Injection of venom:2 Types: hemotoxins = affects blood neurotoxins = affects nerves

Snakes:Fangs:

~ back of throatElapids:

~ 2 small fixed fangs in front of mouth

Vipers:~ 2 retractable fangs on roof of mouth Ex: copperheads & rattle snakes

Order Rhynchocephalia:

Order traits:1. New Zealand2. Third eye

- sun detector- on crest of head

~ burrow during the day~ hunt insects at night