What are
animals?
Animals are multicellular, heterotrophs
that have evolved to live in many
different habitats
Characteristics of animals
• Body support
• Multicellular
• Adaptations to
environment
• Movement
• Heterotrophs
• Absence of a cell wall
• Ability to reproduce
Can be Vertebrates or
Invertebrates
Vertebrates are
organisms
containing
backbones
Invertebrates are
organisms
without
backbones
All animals are
multicellular
• Organisms are created from more than one cell
• Even though animals come in a variety of sizes, the
overall cell sizes are very similar
All animals have
specialized parts
All animals have developed a variety of
adaptations to survive in their environment.
• Animals can swim, crawl, walk,
and even fly
• Some animals can only move
in the larval stages (Ex:
sponge)
Animals are heterotrophs
Animals must consume other things for energy
and can not create their own food (energy.
Animals do not have cell walls
Animal cells lack a rigid cell wall which
has allowed them the mobility that other
multicellular organisms don’t have.
Instead of a cell wall,
animal cells have collagen
Collagen is a three stranded protein that provides support
to animal cells. It is strong and flexible which allows cells to
move within the animal’s body.
Animals can reproduce
sexually or asexually
Sexual Reproduction
Some organisms reproduce
sexually
• Typical sexual
reproduction takes place
when a male forms
sperm and a female
creates eggs.
• In hermaphrodites one
organism can create both
egg and sperm, but still
needs a mate.
Asexual Reproduction
Asexual reproduction is when a single
parent produces genetically identical
offspring
• Budding; An offspring develops as a
growth on the body of the parent
• Fragmentation: The parent breaks into
pieces and each piece becomes a
new individual
• Regeneration: A new organism can
regenerate, or regrow from the lost
body part of the parent
• Parthenogenesis: A female produces
eggs that develop without being
fertilized.
In all animal species, the
organisms that reproduce
are diploid and their
offspring are also diploid.