This document summarizes the key characteristics of different vertebrate groups. It describes that mammals nourish their young with milk and have hair or fur, birds have feathers and are able to fly, amphibians live both on land and water and undergo metamorphosis, reptiles lay eggs and have scaly skin, and fish are cold-blooded and breathe through gills. The document outlines distinguishing features of these five vertebrate classes.

1. Vertebrate
Characteristics

2. Mammals (Mammalia)
 Mammals nourish their offspring with milk
 They have hair or fur that is made up of
keratin
 They are endothermic, meaning mammals
can maintain a consistent body temperature
 Some are Eutherians. They give birth to live
young. While the offspring is in the uterus, it
receives nutrients from the mother.
 Others are Monotremes, and they lay eggs.
The nutrients for the offspring derives from the
shelled egg.
 Lastly, is the Marsupials. Like Kangaroos, they
young is born early and kept in a pouch and
continue developing and nursing.

3. Birds (Aves)
 Similarto mammals, birds are also
endothermic. Also birds are warm-
blooded.
 Birds contain wings made up of feathers.
They are able to grow new feathers each
year.
 Because for their light weight and wings,
birds are able to fly in the sky.
 Depending on their species, birds can
either be carnivores or herbivores.

4. Amphibians (Amphibia)
 For amphibians, life begins underwater
breathing through gills.
 As the mature into adults, these animals move
from the water to land and breathe through
their newly-developed lungs and-or skin.
 Amphibians will live in both water and on
land.
 These carnivores feast on various items
depending on their habitat and location.
 At some point in their lives, most amphibians
will undergo metamorphosis.

5. Reptiles (Reptilia)
 Reptiles have scaly skin and three
chambered hearts. However, the larger
reptiles such as reptiles and crocodiles
who possess four chambered hearts.
 They are cold blooded and have well-
developed lungs.
 Instead of giving birth, reptiles lay eggs.

6. Fish
 Fish are ectothermic, meaning they are able
to control the temperature of their fragile
bodies.
 They have two chambered hearts and gills for
respiration, however they do not have eyelids
or external ears.
 Because of their lack of body parts, fish
contain an organ called lateral line. This
sensory organ allows the fish to feel vibrations
when a movement has occurred near them.
Fish are able to hide from predators and use
this organ as a security measure.