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Kingdom Animalia …
The final frontier
Mr. Francis
 a
2 main categories
 Invertebrates
 No backbone
 Vertebrates
 Backbone
Key Characteristics of
Animals
 Multicellular
 Heterotrophic
 No cell walls
 Eukaryotic
 Most also move and have some sexual reproduction
Animal Diversity
 1
Animal Development
 All organisms start off as a single cell
 This cell undergoes mitosis in which each division
results in a doubling of number of cells
 A hollow ball of cells, called the blastula forms
Animal Development
 The blastula begins to fold inwards by a process called
gastrulation
 Gastrulation results in the formation of body layers
called germ layers
There are Three Germ Layers
 1. Ectoderm: forms outer layer of body (gives rise to
skin, nervous system, feathers, scales, hair, nails)
 2. Endoderm: Forms inner layer of body (stomach
lining)
 3. Mesoderm: Forms middle layer (organs of
circulatory, respiratory, excretory & digestive systems)
There are Three Germ Layers
 The more complex an organism is, the more highly
evolved and specialized the tissues and organ systems
are  specialization results in organization (groups of
specialized cells have unique functions within
organisms)
Body Cavities
 “Simple” animals have a pouch-like gut with only one
opening (food enters and wastes leave through the
same opening)
 Shared mouth and anus
 More complex animals have a gut with two openings (a
mouth and an anus) which allows for one-way
movement of food
 Regions of the gut can become specialized for certain
activities (an area for grinding or chewing food, or
chemical digestion, an area for absorption of nutrients
and water)
Body Cavities continued
 Coelom: fluid filled space or cavity located between gut
and body wall  where all internal organs are found
Body Cavities continued
 Allows more room for organs (lungs, heart, stomach) to
grow and develop
Body Cavities continued
 Allows more space for organs to fold/loop/coil –
increases organs surface area to volume ratio
Body Cavities Continued
 Draw me
Symmetry (shape)
 Assymetrical: no symmetry (no particular pattern)
 Radial Symmetry: any vertical cut made through the
center of the organism will result in two identical halves
Symmetry Continued
 Bilateral symmetry:
Organism has a left and
right side – only one
vertical cut through the
organism’s center will
result in two (relatively)
identical halves
Symmetry Continued
 The symmetry of an organism is related to its
development and how much an organism moves
Symmetry continued
 Symmetry also provides information about complexity
and evolutionary development of an organism
 Bilateral symmetry is found in more complex and more
highly developed organisms, like some of you.
Invertebrates with radial
symmetry
 Usually sessile (sedentary) or move very little since
they do not have a head (there isnt one region which
always leads)
 Usually dependent on environment to bring them food
and help them reproduce
Invertebrates with bilateral
symmetry
 Are usually motile
Invertebrates with bilateral
symmetry
 Are usually motile
 Usually show cephalization (development of a definite
head) in the anterior end
 Since animals usually move with anterior end first, this
end usually contains eyes and sensory devices –
allows organisms to detect its environment as it moves
(ie to detect food, danger, changes in the environment)
Invertebrates with Bilateral
Symmetry
 Even though it may appear more advanced to have
cephalization, not all organisms need to have a head in
order to survive
Ends and sides
 Note:
 Anterior = front end
 Posterior = back end
 Dorsal = upper side
 Ventral = lower side
Assignment
 Page 663 # 1-5
 When you are finished, draw an animal from another
planet and label it with adaptations suited to its
environment. Describe the environment as well.