Vertebrates

Fishes

All fishes are ectotherms. Ectotherms- animals with body

temperatures dependent upon the temperature of their surroundings.

Fish have a two chambered heart and breath through gills.

Different types of fishes are grouped into three different classes, jawless fishes, cartilaginous fishes and bony fishes.

Fishes cont. Jawless Fishes

Types of jawless fishes are lampreys and hagfishes.

Jawless fish have endoskeletons made of cartilage like sharks and types of rays.

Fishes cont. Cartilaginous fishes Types of cartilaginous fishes are

sharks, skates and rays. Evidence has proven that jaws were

first evolved in this type of fish. Cartilaginous fish have

endoskeletons made of cartilage like jawless fish.

Cartilaginous fish have paired fins and a lateral line system that enables them to detect movement and vibrations in water.

Fishes cont. Bony Fishes

Most fishes belong to the bony fish class.

All bony fishes have a bony skeleton, gills, paired fins, flattened bony scales and a lateral line system.

Bony fishes breath by drawing in water into their mouth then passing it over the gills where gas exchange occurs.

They adjust their depth in the water by regulating the amount of gas that diffuses out of their blood into the swim bladder.

Amphibians

Amphibians are ectothermic with three chambered hearts, lungs and thin moist skin.

Most gas exchange is carried out through the skin not the lungs. Adult amphibians live on land but rely on water for reproduction. Almost all amphibians go through the process of metamorphosis. Metamorphosis- which the young hatch into tadpoles, then

gradually lose their tails and gills as they develop legs, lungs and other adult structures.

Amphibians can be classified into three orders Anura, Caudata and Apoda.

Amphibians cont. Anura are considered to be frogs

and toads. Anuras have vocal cords that can

produce wide range sounds. Frogs have think, smooth, moist skin. While toads have thick bumpy skin

with poison glands. Caudata are considered to be

salamanders and newts. Salamanders have long, slender

bodies with a neck and tail. Apoda are considered to be

legless caecilians. Caecilians have long, wormlike

bodies with no legs.

Reptiles Reptiles are ectotherms with dry, scaly skin

and clawed toes. Types of reptiles are snakes, lizards, turtles,

crocodiles and alligators. All reptiles have four legs that are positioned

under the body except snakes. Most reptiles have a three chambered heart

except for a crocodile it has a four chambered heart.

The scaly skin of reptiles reduces the loss of moisture on land scales also prevent the skin from absorbing or releasing gas.

Reptiles are dependent on lungs for the essential gas exchange.

Reptiles lay amniotic eggs to reproduce.

Birds

Birds are the only class of animals to have feathers.

Feathers are lightweight, modified scales, that help insulate birds and enable them to fly.

They have wings which are modified forelimbs.

Similar to reptiles birds have scales on their feet and clawed toes.

Unlike reptiles they are endotherms. Endotherms- animals that maintain a

constant body temperature. Endotherms must eat frequently to

provide energy needed for producing heat.

Birds cont. Birds have thin hallow bones with

cross braces that provide support for strong flight muscles while reducing their body weight.

Birds have a four chambered heart.

Birds have a unique respiratory system which oxygen is available through exhalation and inhalation.

Like reptiles birds lay amniotic eggs but unlike reptiles birds incubate their eggs in nests. The nest keeps the egg warm till the young birds hatch.

Mammals Mammals are endotherms. Mammals are named after their

mammary glands, which produces milk to feed their young.

Most mammals have hair which is used to help insulate their bodies and sweat glands that help keep them cool.

Mammals need a high energy level for maintaining body temperature and high speeds of locomotion.

Mammals have a efficient four chambered heart and muscular diaphragm beneath the lungs to help deliver oxygen for their activities.

Mammals cont. All mammals have internal fertilization and the young begin development inside the

mothers uterus. Mammals are divided into three large groups monotremes, marsupials and placental. Monotremes are mammals that lay eggs. Marsupials are mammals which the young complete a second stage of development

after birth in a pouch made of skin and hair on the outside of the mothers body. Placental mammals carry their young inside the uterus until development is nearly

complete. Mammals can also be classified by their teeth, how many they have and type. Types of teeth are incisors, canines, molars and premolars. Incisors are used to cut food. Canines are long pointed teeth used to stab or hold food. Molars or premolars have flat surfaces with ridges and are used to rind and chew food.