Vertebrates

Fishes - All fishes are ectotherms (cold blooded). 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 bony fishes

Jawless Fishes Jawless fish have endoskeletons made of cartilage like sharks and types of rays. Types of jawless fishes are lampreys and hagfishes.

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.

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. They adjust their depth in the water by regulating the amount of gas that diffuses out of their blood into the swim bladder. Bony fishes breath by drawing in water into their mouth then passing it over the gills where gas exchange occurs.

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

Amphibian Orders Anura are considered to be frogs and toads. Anuras have vocal cords that can produce a wide range sounds. - Frogs have thin, smooth, moist skin. - While toads have thick bumpy skin with poison glands. Caudata are considered to be salmanders 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.

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. - 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. - -

Birds continued Similar to reptiles birds have scales on their feet and clawed toes. 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. - Unlike reptiles they are endotherms. - Endotherms- animals that maintain a constant body temperature. (warm blooded) - Endotherms must eat frequently to provide energy needed for producing heat.

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

Mammals continued Monotremes Marsupials Placental All mammals have internal fertilization and the young begin development inside the mothers uterus. Monotremes Mammals that lay eggs instead of giving birth to live young like other mammals. Found in Australia and New Guinea. Ex. Platypus, Spiny Anteaters Marsupials Mammals in which the young complete a second stage of development after birth in a pouch. It is made of skin and hair on the outside of the mothers body. Ex. Koalas, Kangaroos, Possums, Tasmanian Devil Placental Mammals that carry their young inside the uterus until development is nearly complete. Ex. bison, humans, elephants, wolves, Cats, squirrels, bats

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 grind and chew food.