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Vertebrate Characteristics

Classification of Vertebrates!a.  Phylum: Chordata !! !Common Characteristics: "

!notochord, pharyngeal gill slits, hollow dorsal nerve cord!b. !Sub-phylum: Vertebrata!! !Common Characteristics: "

!backbone that supports and protects spinal cord, endoskeleton, distinct !head with skull and brain!

!

Lancelet

Tunicate

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1.  Vertebrate Class Definitions!a.  Fish - aquatic vertebrates that are characterized by scales, fins

and pharyngeal gills. There are 3 main groups: jawless, cartilaginous and bony. Ex. Lamprey, dogfish shark, perch.!

b.  Amphibians - vertebrates that are aquatic as larvae and terrestrial as adults. They breathe with lungs as adults, have a moist skin with glands and lack scales and claws. Ex. Frog, salamander, newt.!

c.  Reptiles - vertebrates that have lungs, scaly skin and a special type of egg (amniotic). They live entire life out of water. Ex. Snake, lizard, turtle.!

d.  Birds - endothermic, reptile-like vertebrates with feathers, two legs used for walking and perching and wings that usually don’t have claws. Ex. Pigeon, hawk, eagle.!

e.  Mammals - endothermic animals with fur or hair, and mammary glands that produce milk to nourish young. Almost all give birth to live young. Ex. Human, whale, fetal pig. !

Part A: Overview of Vertebrate Classes!

Part B: Important Evolutionary Advances!Jaws- Fish!

•  The first fishes to be found in abundance in the fossil record were jawless. These are limited to eating small particles of food by filter-feeding and vacuum suction.!

•  Jaws in fishes made it possible for them to eat plants and other animals and defend themselves by biting. !

•  Disadvantage-digestive system had to develop for new diet!

Strong Skeleton- Amphibian Adults!

•  The first amphibians had strong limb bones and girdles for movement unsupported by water.!

•  The ribs formed a cage that supports and protects the internal organs. !

•  Adult amphibians have more mobility and habitat availability!

•  Disadvantage- new environment, predators!

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Eggs- Reptiles!•  Reptiles evolved from amphibians when climatic changes caused

destruction of amphibian habitat. !•  Reptilian eggs are surrounded by a shell and several membranes that

create a protected environment for the embryo. !

•  These “amniotic eggs” contain nutrient-rich yolk used by the embryo for food.!

•  Disadvantage- predators, change in habitat.!

!Internal Temperature Control- Birds and Mammals!•  Fish, amphibians and reptiles are ectothermic. The have an internal

body temperature that varies with external (environmental conditions) due to a slow metabolism.!

•  Birds and mammals are endothermic. They maintain a relatively high and constant internal body temperature that is regulated internally due to a fast metabolism.!

•  This adaptation is very important for animals living in habitats where temperatures and seasons are variable.!

•  Disadvantage- more food must be consumed !

Iguana Polar Bear

Penguin

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Feeding and Digestion!

Herbivorous Digestive Systems Carnivorous Digestive Systems -Can eat constantly -Long coiled digestive system which helps break down plant material -Iguanas -Teeth are flat for breaking down cellulose rather than for tearing meat

-Shorter digestive system so meat wont rot -Sticky tongue (frogs and salamanders) to catch insects -Snakes swallow animals whole-unhinge jaw -Birds: beaks & claws; crop & gizzard; large intestine absent or reduced

BENEFITS: Increases time for complete digestion Allows symbiotic bacteria to digest cellulose

BENEFITS: Sharp teeth tear meat Short tract speeds enzymes that convert meat to energy

Feeding and Digestion!

Digestive Systems!

Part C: Comparing Structure and Function Among Vertebrates!

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Similarities Differences

Lungs- adult amphibians, reptiles, birds, mammals. 2 lungs- reptiles, birds, mammals Gas exchange occurs in lungs

Gills- fish, amphibian larva Skin or lining of mouth- amphibians Reptiles- more spongy lungs which are more efficient than amphibians. Strong muscles around rib cage. Snakes- one lung. Fish- some have lungs, lungfish Birds- air sac allow for one way flow of air where lungs constantly receive oxygen rich blood Mammals- diaphragm increases volume of lungs and pulls air into lungs

Benefits Lungs are more efficient than gills or skin gas exchange More surface area= more efficient

Respiratory Systems and Lungs!

Respiration!

Fish Gills

• Oxygen rich water is pumped over gill filaments where gas exchange occurs.

• Oxygen poor water is pushed out through openings in the sides of the pharynx.

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Respiration!

Various Lungs!

Circulation/Internal Transport!

SINGLE LOOP Fish: Closed system from heart to gills, from gills to the rest of the body and back to heart. Two chambers in heart.

DOUBLE LOOP Adult Amphibians: one loop carries oxygen poor blood from heart to lungs, other loop carries oxygen rich blood from heart to rest of body. Has 3 chambers. Reptiles: 3 chambers but more efficient due to septum in ventricle. Crocs and Alligators have 4 chambered heart. Birds and Mammals: 4 chambers. Complete separation of oxygen rich and oxygen poor blood= most efficient.

Deliver oxygen

and nutrients to cells

and remove wastes.

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Circulation/Internal Transport!

Heart Chambers and Circulatory Systems !

The DOUBLE loop creates one loop from the heart to the lungs and a second loop is from the heart to the body.!!Double loop circulation allows for the development of more advanced lungs - more spongy and highly branched.!

Reproduction!

Definitions!• Oviparous: a vertebrate that lays eggs that develop outside the mothers body. Most fish- salmon. Most reptiles and birds have amniotic eggs.!

• Ovoviviparous: a vertebrate whose eggs develop inside the mother’s body but are not nourished directly by the mother’s body. Some reptiles-snakes & lizards. Guppies.!

• Viviparous: a vertebrate who bears live young and directly nourishes the unborn young by the mother’s body. !

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External:!Eggs are fertilized OUTSIDE the mother’s body.!

Adults release eggs and sperm into the surrounding water and sperm swim to the eggs to fertilized them. !

To increase chances, huge numbers of eggs and sperm are released.!Most amphibians (except salamanders)

Internal: !Eggs are fertilized INSIDE the mother’s body.!

Sperm is deposited into the body of the female. !Female’s reproductive system covers the embryos with protective membranes and a shell!

Reptiles, birds, mammals!

Allows ���for the

species to reproduce,

to continue

on

Fertilization!

Fertilization!

External Fertlization Internal Fertilization

Bene

fits

Large number of offspring produced No specialized reproductive structures needed

With attention and maternal care, high percentage of offspring survive

Dra

wba

cks

Low percentage of offspring survive with no parental care, eggs lost to predators

Only small number of offspring produced Need specialized reproductive structures

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The End

The End

The End