Fish, Amphibians, Reptiles

Chordates

• Four characteristics present at some stages of their development– Notochord- extends along upper part of body for

support– Postnatal tail- muscular structure at end of

developing chordates– Nerve cord- develops into the brain and spinal cord– Pharyngeal pouches- found in region between

mouth and digestive tube

Vertebrates

• Have all chordate characteristics but additionally

• Have endoskeleton, and part of it is stack of vertebrae and cartilage

• Either cold blooded ectotherms or warm-blooded endotherms

Fish

• Ectotherms with streamline shape, muscular tail, fins, and scales

• Exchange carbon dioxide and oxygen through gills

• Reproduce sexually, either external or internal fertilization

Types of Fish

cartilaginous• Skeletons made of cartilage,

movable jaws with well developed teeth, and tiny scales that make their skin feel like fine sandpaper

Bony fish• Skeletons of bone• Swim bladder that inflates

or deflates• About 95% of all fish

Amphibians

• Ectotherms that engage in hibernation in cold weather and estivation in hot weather

• Some breathe through skin, others have small lungs

• Need water for reproduction because eggs fertilized externally

• Most go through metamorphosis• Frogs, toads, newts, salamanders

Reptiles

• Ectotherms with thick, dry, waterproof skin covered with scales.

• Breathe with lungs• Internal fertilization and lay eggs with shells.– Amniotic egg provides a complete environment

for embryo’s development

Three Reptile Groups

• Lizards and snakes have jaws that unhinge so they can swallow their prey whole

• Turtles have two part shell made of hard, bony plates that protects against predators

• Crocodilians are lizard shaped with large, deep scales on their backs– Crocodiles have narrow head with triangular shaped snout

while alligators have broad head with rounded snout. Gavials have slender snout with large bump on the end

– Among few reptiles that care for young

Birds

• All have feathers and scales and lay eggs• Bird eggs– Shell made of calcium carbonate– Clutch- group of eggs laid by female bird– Parent incubates egg to keep warm until it hatches

Flight Adaptations

• Lightweight, strong skeleton• Wings• Feathers• Strong flight muscles• Efficient respiratory system• Well-developed senses

Bird Features

• Bones are hollow to be lighter• Feathers– Contour feathers give birds their coloring and

smooth shape. Used for flight– Down feathers provide birds with an insulating

layer to keep them warm– Preening is a process where birds rub oil on its

feathers to condition them

Wings

• Move up down, back forth

• Shape provides upward push called lift for flight

• Also can be used for swimming and balance

Importance

• Food source, pets, pest control, flower pollinators, seed dispersers

• Evolved from reptiles– Archaeopteryx oldest bird fossil found

Mammals

• Have hair and produce milk for young• Skin and glands

– Skin produces fur or hair, horns, claws, nails, or hooves– Mammary glands make milk for feeding young– Oil, sweat, scent glands, too

• Hair– Keeps mammals warm– Whiskers help animals sense their environment– Blubber- how animals with no hair keep warm– Quills and spines are modified hairs that protect animals

from predators

Teeth

• Incisors, premolars, canines, and molars

• Omnivores have all types of teeth

• Carnivores have large canine teeth for eating meat

• Herbivores have premolar and molar teeth to eat plants

Reproduction

• All mammals produce sexually• Most mammals give birth to live young• Young feed on milk while learning survival

skills

Types of Mammals

• Monotremes- lay eggs and have no nipples on mammary glands

• Marsupials- give birth to immature young that usually feed and develop in mother’s pouch

• Placentals- develop embryos inside mother’s uterus– Gestation period- amount of time embryo develops in

the uterus– Placenta- organ inside uterus, absorbs oxygen and food

from mother’s blood– Umbilical cord- how embryos connect to placenta

Monotremes

Marsupials

Placental

Mammal Importance

• Carnivores control populations of grazing animals

• Mammals pollinate flowers and distribute seeds

• First developed around 65 million years ago when dinosaurs become extinct