What is an Animal?
• There are about 1 million species of animals.
• About 95 percent of them are invertebrates,
animals without a backbone.
• Examples: jellyfish, insects
• Any animal with a skull and
backbone is a vertebrate.
• Examples: fish, birds
Animals share characteristics that separate
them from all other living things:
• All animals are multicellular. The cells are
eukaryotic and do not have a cell wall.
• Animals usually use sexual reproduction.
A few animals, such as sponges and sea
stars, can reproduce asexually by budding
or fragmentation.
• Animals have specialized body parts.
When a fertilized egg cell divides to form
an embryo, some cells become skin cells,
others may become muscle, nerve, or
bone cells. Most animals also have
organs, a combination of two or more
tissues.
• Animals move. Some other organisms
move, but animals are more likely to move
quickly in a single direction. A few animals
do not move much, such as sea
anemones and clams.
• Animals are consumers. They eat other
organisms because they cannot make
their own food.
Animal Behavior- activities that help
animals stay alive
• Innate behavior- doesn’t depend on
learning or experience, it’s in the genes. It
may be present at birth or years later.
Examples: whales can swim, birds can sing
• Learned behavior- learned from
experience or watching other animals, can
modify innate behavior
• For example: Humans are born knowing
how to speak, but the language is learned
not inherited
Survival Behaviors:
• Finding Food
Predators- animals that
eat other animals
Prey- the animal
being eaten
• Camouflage- blending in with the
background
• Defenses- horns, spines, chemicals
• Animals with a chemical defense often
have warning coloration
Seasonal Behaviors:
• Some animals migrate- travel from one
place to another to find food, water, or
safe nesting grounds
• Hibernation- having a period of inactivity
and decreased body temperature to deal
with food and water shortage.
• Estivation- period of reduced activity in
the summer, some desert squirrels and
mice do in the hottest part of the summer.
Social Behaviors:
• Communication- signal traveling from
one animal to another and the receiver
responds
• Examples: find food, avoid enemies,
protect homes, warn of danger
• Pheremones- chemicals
• Noises- sound can reach a large number
of animals over a large area
• Body language
• Touch