Unit 4: Animal Systems
An Introduction to Animals
Mr. Chapman
Biology 30
Animals are Physically Diverse

Animals are the most physically diverse
kingdom of organisms.

Animals can be found nearly everywhere
on earth, including some places in which
plants and fungi do not live.

Some have the most boring lives that you
could ever imagine.
A Sponge’s Life Sucks...
Sponges have long been considered the most
primitive animals on earth. They spend their entire
adult lives fixed to a single spot, filtering water to
collect microscopic particles of food.
To learn more about
these thrillers, see
section 23.3 of the
textbook. We will not
cover them in class
except to say this:
570 million year old
sponge fossils have
been found, making
them among the most
ancient animals.
All Animals Share a Set of
Characteristics...

Can we come up with a list of common
characteristics that all animals share?
Animals are multicelllular.
2. All animals have eukaryotic cells.
3. Animals are heterotrophs (they eat other
organisms) They lack chloroplasts to make
their own food.
4. Animal cells are supported by collagen.
5. Animals are diploid.
1.
Animals Must Eat

Anything that an animal uses for cellular
respiration must come from an outside
source. This includes sugars, proteins, and
fats.

Single-celled protists also eat other
organisms, but because even the simplest
animal is composed of many cells, it can
eat bigger things than a protist can.
Vertebrates and Invertebrates

A vertebrate is an animal with an
internal segmented backbone.

You are a vertebrate, and so are other
animals. However, we only make up a total
of 5% of all the known animal species.

Invertebrates are animals without
backbones. They make up the vast
majority of animals on the planet.
An Outdated System of
Classification

Previously, scientists used to classify
animals initially based on their status as
vertebrates or invertebrates.

As biologists learned more and more
about animals, it became clear that
invertebrates were so diverse from each
other that they should not necessarily be
categorized together anymore.
Animal Phyla

Because of this, scientists now use shared
characters to divide animals into more than
30 major groups.

Each group, or phylum, of animals is defined
by structural and functional characteristics
that are different from every other animal
group.

Each animal phylum has a unique body plan
and represents a different way that a
multicellular animal is put together.
Invertebrates

1.
2.
3.
4.
The invertebrates include many
different phyla, such as the following:
Sponges and cnidaria
Mollusks
Arthropods
Nematoda
Snails and octopi are
in the same phylum...
Mollusks. What’s the
deal?
Percentage of Invertebrate Species
Many Criteria Indeed...
ANIMALS ARE
GROUPED USING A
VARIETY OF CRITERIA..
1.
2.
3.
Body Plan Symmetry
Tissue Layers
Developmental Patterns