Download What is an animal?

What is an animal?
Ms. Williams
Biology A
Characteristics of Animals
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Animals are eukarytoic
Animals are multicellular
Animals are heterotrophic
Animals must digest their food - in some
animals it is done within cells, in other
animals it is done in an internal cavity
Characteristics continued
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Animals must reproduce - can be
asexually or sexually
Animals move at some point in their
lives
Animals adapt
Development of animals
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How do you get from a single fertilized
egg to a complete organism?
1.
2.
Fertilization - sperm & egg form a zygote
Cell division - cells divide until a hollow
ball called a blastula forms
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3. Gastrulation - the
cells on one side of
the blastula fold
inward forming a
gastrula
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The gastrula is made of two layers with
an opening at one end
The outer layer is the ectoderm
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This forms the skin and nervous system
The inner layer is the endoderm
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This forms the digestive tract
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In some animals, a third layer is formed
called the mesoderm, in the middle of
the embryo
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The mesoderm forms the muscles,
circulatory, excretory and respiratory
systems
Cell layers
Gastrula opening
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In some animals like earthworms, the
gastrula opening becomes the mouth.
These animals are called protostomes.
In other animals, the opening does not
develop in the mouth. The mouth
develops from cells somewhere else in
the blastula. These animals are called
deuterostomes. Ex - birds & humans
4. Continued growth & development
5. Adult
Animal organization
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Animals are made of
cells.
Groups of cells
make tissues.
Groups of tissues
form organs.
Groups of organs
form systems.
Anatomical terms
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Anterior - the head end of an organism
Posterior - the tail end of an organism
Dorsal - the organism’s back side
Ventral - the organism’s belly side
Symmetry
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Asymmetry - no
symmetry or
irregular symmetry
Radial - can be
divided along any
plane, through a
central axis
Bilateral - can be
divided down the
middle in halves
Body Plans
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Acoelomate - animal
with all three cell
layers but no body
cavity
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Pseudocoelomate animal with a false
body cavity
Pseudocoelom - a
fluid filled body
cavity partially lined
by mesoderm
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Coelomate - animals
with a true body
cavity
Coelom - fluid filled
space that is
completely
surrounded by
mesoderm
Support & protection
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Exoskeleton - a hard, waxy covering on
the outside of the body that provides a
framework for support
Most invertebrates are animals that
have an exoskeleton, because they do
not have any support
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An endoskeleton, is an internal skeleton
that provides support
Endoskeletons can be made of calcium
carbonate, like in sea stars; cartilage,
like in sharks; and bone, like in
vertebrate animals
Endoskeletons protect internal organs
as well as attach muscles