Fishes, Amphibians, Reptiles

Section 1: What is a Vertebrate? Characteristics of

CHORDATES

Most are Vertebrates (have a spinal cord)

Some point in life cycle all chordates have:

Notochord

Nerve cord that runs down their back (like a spinal cord)

Slits in their throat area

NOTOCHORD

Flexible rod that supports a chordate’s back

Lancelet has a notochord its whole life

All vertebrates have part or all of notochord replaced with a backbone

SLITS in Throat Area

Also called Pharyngeal slits (or gill slits)

Fish have them their whole life

In humans, they disappear before birth

Characteristics of Vertebrates Most chordates

Has backbone that is part of an internal skeleton

Backbone = spine

Formed by bones called vertebrae

Joints in between each bone provide flexibility

Hole through each vertebrae for spinal cord

Makes up part of endoskeleton

Protects internal organs

Gives body its shape

Does not need to be replaced

Location for muscle attachment

Allows greater growth

Keeping Conditions Stable Ectotherms

Fish, reptiles, amphibians

Animal whose body does not produce much internal heat

Body temperature changes based on temperature of the surrounding environment

Endotherms

Birds and mammals

Animals that regulate their own body temperature

Adaptations including sweat glands, fur/feathers

Larger variety of suitable living environments

Section 2: Fishes Aquatic vertebrate with fins

Most are ectotherms

Obtain oxygen through gills

Have scales

Largest group of vertebrates

Three major groups:

Jawless

Cartilaginous

Bony

Obtaining Oxygen Fish opens its mouth and

take a gulp of water

Water moves through throat and then to gills

Gills contain many blood vessels

Oxygen diffuses into blood vessels

Carbon dioxide diffuses out

Water flows out of slits beneath the gills

Circulatory System

Oxygen-rich blood travels through closed system

Two-chamber heart

Pumps blood in one loop

Heart gills rest of body back to heart

Reproduction External fertilization

Eggs fertilized outside of female’s body

Male hovers close to female

Male spreads a cloud of sperm cells over released eggs

Young develops outside of female’s body

Internal fertilization- sharks, guppies

Eggs fertilized inside of female

Female gives birth to offspring

Jawless Fish No jaws and no scales

Mouths designed for scraping, stabbing, and sucking their food

Hagfishes- scavengers w/ large, slimy worm-like bodies

Lampreys- Parasites of other fish

Cartilaginous Fish Skeletons made of cartilage

Have jaws and scales

Sharks, rays, skates

Usually carnivores

Rays and skates- hunt on ocean floor for mollusks, crustaceans, and small fish

Sharks- attack and eat anything that smells like food

Used jagged teeth arranged in rows

Only front teeth are used for feeding

Teeth move forward if front teeth are lost

Bony Fishes 95% of all fish

Trout, tuna, goldfish

Skelton made of hard bones

Scales and a jaw

Pocket on each side of the head that hold the gills

Swim bladder

Internal, gas-filled sac

Helps stabilize fish at different depths

Section 3: Amphibians Means “double life”

Beginning of life in water, adult life on land

Return to water to reproduce

Ectothermic vertebrate

Two groups:

Salamanders- keep tails in adulthood

Frogs and toads- no tail in adulthood

Reproduction and DevelopmentFROGS SALAMANDERS

-Eggs are fertilized externally and developin water-Larvae wriggle out of jelly that coat the eggs-TADPOLES = frog larvae-Begin a free-swimming fish-like life

-Eggs are fertilized internally-Larvae looks like adults-During metamorphosis, they lose their gills-Changes during metamorphosis are not as dramatic

Living on Land When amphibians become adults, multiple

adaptations occur:

Lose gills and develop lungs for gas exchange

Circulatory system changes from single loop with a 2-chamber heart to two loops with a 3-chamber heart

Atria- two upper chambers

Left gets blood from lungs

Right gets blood from body

Ventricle- lower chamber

pumps blood out to both

lungs and body

More Adaptations Change from herbivores to carnivores

Develop camouflage to help obtain food

Develop skeletons and muscular limbs

Powerful hind-leg muscles for jumping

Skelton to absorb shock when landing

Changes to the feet

Webs to aid in swimming

Sticky pads for climbing

Section 4: Reptiles Ectothermic vertebrates with lungs and scaly skins

Snakes, lizards, turtles, alligators

Can spend entire life on land

Adaptations for water conservation:

Dry, tough skin with scales

Kidneys filter wastes which are excreting as urine

Amniotic egg prevents embryo from drying out

Amniotic Egg Reptiles exhibit internal

fertilization

Lay eggs on land

Egg contain shell and 4 internal membranes

Shell has pores for gas exchange

4 Membranes for:

Holding liquid that surrounds embryo

Holding yolk (food for embryo)

Holding embryo’s wastes

Exchange of O2 and CO2

Lizards Skin with overlapping

scales

Shed their skin and scales as they grow

4 legs with claws on toes

Long tails, external ears, movable eyelids, two lungs

Carnivores that jump at their prey

Eat frogs, birds, insects depending on size

Snakes Identical skin qualities as lizards

No legs, streamlined bodies, no external ears or eyelids

Most have only one lung

Eat small animals like mice

Use long front teeth for hooking

Some inject venom via their fangs

Jawbones can spread apart

Skull bones can move to swallow large prey

Alligators and Crocodiles Largest living reptiles

Take care of their young

Carnivores that hunt at night

Hunting/Eating adaptations include:

Strong, muscular tails fro swimming

Jaws with large, sharp, pointed teeth

Strong jaw muscles for biting down

Alligator and Crocodile Reproduction Care for eggs and newly hatched young

Female stays near the nest

Periodically, she will crawl over nest from the water to keep it moist

Once eggs hatch, mother will scoop them up in her mouth and carry them away to a safe area in the water

May stay with young up until a year or when they can feed and protect themselves

Turtles Reptile covered by

protective shell w/ ribs and a backbone

Shells are either hard or soft

Some can bring head, legs, tail inside for protection

Tortoises = land turtles

Have sharp-edged beak instead of teeth for eating

Can be carnivores or herbivores

Extinct Reptiles- Dinosaurs

Ancestors of reptiles

Extinct 65 million years ago

Some may have been endothermic

Herbivores walked on 4 legs

Carnivores walked on 2 legs

Section 5: Vertebrates History in Rocks What are Fossils?

Hardened remains of living things

Bones, shells, skeletons

Tissues are replaced by hard minerals

Found in sedimentary rocks

Layered rocks containing particles of:

Clay

Sand

Mud

Silt

More on Fossils Paleontologist = scientists who study extinct

organisms by:

Examining fossil structures

Making comparisons to present-day organisms

Can determine approximate age by:

Studying sediment layers

Examining radioactive decay

Vertebrate Evolution Fish- 530 million years ago

Amphibians- 380 million

Reptiles- 320 million

Mammals- 220 million

Birds- 150 million

Birds and Mammals are both descendants of reptiles