Evolution of the Tetrapods

Evolution of the Tetrapods

The Origin of Tetrapods• The first vertebrates on land were

amphibians in the _________(400 mya)• Arose from the rhipidistian (a family of

lobed finned fish) (based on morhpology) or a lungfish (DNA)

Origin of Tetrapods

Classification

• Phylum: Chordata• Subphylum: Vertebrata• Superclass: Gnathostomata• Class: Amphibia

– Order: Urodela (Salamanders)– Order: Anurans (Frogs and Toads)– Order: Apodans (Caecilians)

Class: Amphibia• Two lives

– refers to metamorphosis of many frogs• Skin smooth and moist (cutaneous

respiration)• _____ chambered heart with a double

circulation system

Order: Urodela

• 400 species• Salamanders• Retain their tail as

adults• Limbs are at right

angles to the body• Carnivorous• Most have internal

fertilization using a _____________

• Axolotl - paedomorphosis

Order: Anurans• 3500 species• Frogs and Toads• Lose their tail as

adults• Hind limbs are

adapted for jumping• Tongue connected to

front of mouth• Secrete mucus• __________ Fertilization

Order: Apodans

• 150 species• Caecilians• Legless and blind• Mostly Tropical• __________

Fertilization• Usually give birth

to live young.

Gas Exchange

Conditions for Respiratory Surfaces

• Large surface area• Thin• Moist

Aquatic vs. Terrestrial• Less than ____%

oxygen• Oxygen amounts

decrease as the temperature increases

• Aquatic animals use large amounts of energy to obtain oxygen (____%)

• About _____% oxygen

• Developed invaginations to increase surface area and decrease evaporation

• Terrestrial animals may use only 1% - 2% of its energy to obtain oxygen

Gills• Found in echino-

derms, mollusks, annelids, arthropods, some vertebrates

• Countercurrent Gas Exchange

Countercurrent Gas Exchange• Maintains gradient over the whole length of

the capillaries• Extracts ____% of the oxygen from the

water

Tracheal Systems

Diffusion Lungs

• Found in invertebrates• Gas moved primarily by diffusion

– may be increased by body movement

• Modifications– snails - cavity with gill modified into lung– scorpions and spiders - invaginations of

the abdomen

Ventilation Lungs

• Found in amphibians, reptiles, mammals and birds

• Pharynx• Larynx• Trachea• Bronchi• Bronchioles• Alveoli

Alveoli

Ventilating The Lungs

• _______ Pressure Breathing– pushes air down

trachea– seen in frogs and

other amphibians

• ________ Pressure Breathing– suction created

by diaphragm– seen in

mammals

Negative Pressure Breathing

Evolution of the _________ Egg

• Allows animals to complete their entire life cycle on land

• Has shell that retains water (or is lost when kept inside mammals)

• Specialized extraembryonic membranes (not part of the animal)

The Amniotic Egg

Evolution of the Amniotic Egg

• Amnion - Protects from dehydration and mechanical shock

• Yolk Sac - Nutrient storage• Albumin (egg white) - Nutrient

storage• Allantois - stores waste, gas

exchange• Chorion - gas exchange• *** Good Essay….

Amniotes

How Reptiles differ from Amphibians

• Tough, dry skin• Amniotic egg• Crushing or

gripping jaws• Copulatory organs• More efficient

circulatory system with a higher blood pressure

• More developed lungs (thoracic breathing)

• Better water conservation

• Better body support and limbs

• Better nervous system

Classification

• Phylum: Chordata• Subphylum: Vertebrata• Superclass: Gnathostomata• Class: Reptilia (not real)

– Class: Testudines (Turtles and Tortoises)

– Class: Spenodontia (Tuataras)– Class: Squamata (Lizards and Snakes)– Class: Crocodilia (Crocodiles and

Alligators)

Reptile Radiation

• Synapsids (therapsids) - led to mammals

• Sauropsids– _________

(turtles)– _________ (all

others)

Class: Testudines (Chelonia)• Protective Shell

– Carapace (top)– Plastron (bottom)

• Land and Sea -Evolved on land and returned to water (lay eggs on land) Largest,

Leatherback Sea Turtle (2,000 lbs!)

Class: Testudines (Chelonia)

• No _____• Most move legs

to breathe • TDS (low:male

high:female)

Class: Sphenodontia• ___________

– Two living species(New Zealand)

– Not a True Lizard (no external ears, different teeth)

– Very Primitive (similar to mesozoic reptiles

– Well developed eye below skin?

Class: Squamata• Lizards

– geckos, iguanas, skinks, chameleons

• terrestrial, burrowing, aquatic, arboreal

• moveable eyelids (in most)

• Paired copulatory organs

Class: Squamata• Tongue usually not

bifurcated• Lower jaw loosely

connected to skull• TSD (female to male)• ______________

Class: Squamata

Class: Squamata

Class: Squamata

Gila MonsterGila Monster – –

• One of three One of three poisonous lizardspoisonous lizards

• Protein in saliva Protein in saliva studied to treat studied to treat diabetes.diabetes.

Class: Squamata• Snakes• Lack limbs• Lack moveable

eyelids

Class: Squamata

• Bifurcated tongue • _________ organ• Pit Vipers (Loreal

Pits)

Class: Squamata

• Venom– Viperidae (Folding

Fangs)• Rattlesnakes

– Elapidae (Fixed Front Fangs)

• Cobras, Sea Snakes, Coral Snakes

– neurotoxic– hemotoxic

Class: Squamata

Feeding Adaptations

• Teeth curved and pointed inward• Hinged __________ bone• Bones of jaw are attached by

muscles and ligaments• Moveable palate• Elastic skin• No sternum

Class: Crocodilia• Largest living reptiles

• Most closely related to dinosaurs

• Complete secondary ________

• Four chambered heart (?)

• Nest temperature (female/male)

Dinosaurs and Pterosaurs

• Dinosaurs – Ornithischian– Saurischian– Pterosaurs– flying reptiles

Animal Structure and Function

(4th exam)

Animal Nutrition

Nutritional Requirements

• Undernourished– not enough

calories

• Overnourished– too many calories

• ____________– missing one or

more essential nutrients

Essential Nutrients

• Essential Amino Acids• Essential Fatty Acids• Essential Vitamins• Essential Minerals

Essential Amino Acids

• Found in proteins– 20 different types

• 8 essential in adult humans (9 infants)

• all in animal proteins• vegetarians need to

eat grains and beans

__________ – Essential in infantsHistidine

Essential Fatty Acids

• Unsaturated fatty acids– used to make phospholipids for

membranes

Essential Vitamins

• Fat Soluble– stored in fat– ___________

• Water Soluble– excreted in urine– B complex and C

Essential Minerals

• Inorganic nutrients– Calcium & Phosphorous

• bones

– Iron• anemia

– Iodine• thyroid hormones

– Sodium, Chlorine, & Potassium• nerve function, water regulation

Food Types

• Heterotrophic– Herbivores– Carnivores– Omnivores– Insectivores

Feeding Adaptations

• Suspension Feeders

Feeding Adaptations

• Substrate Feeders

Feeding Adaptations

• Fluid Feeders

Feeding Adaptations

• Bulk Feeders

Intracellular Digestion

• Inside cells• All animals• Exclusive in:

– Protista– Porifera

Extracellular Digestion

• Outside cells• All animals above the sponges• Two Types

– _________________– _________________

Gastrovascular Cavity

• One opening• Found in

Cnidaria and Platyhelminthes

Alimentary Canal

• Two openings• Allows for

specialization– Mouth– Pharynx– Esophagus– Crop– Gizzard– Stomach– Intestine– Anus

Mammalian Digestion• Accessory Glands

– salivary glands– pancreas– liver (emulsification)– gallbladder

• Peristalsis • Sphincters• “Food”

– bolus– acid chyme– feces

Macromolecule Digestion

Carbo Protein NucleicAcids

Fat

Mouth Initial

Stomach Initial

Intestine Main Main InitialMain

InitialMain

Dentition and Diet• Nonmammal

vertebrates• Carnivores

– canines (grasping/puncturing)

– incisors (tearing)– molars and premolars

• (crushing and grinding)

• Herbivores• Omnivores

Digestive Tracts

• Carnivores– ________

digestive system

– small cecum

• Herbivores– ________

digestive system

– large cecum