ANIMALIA
The final kingdom…
GENERAL CHARACTERISTICS
Multicellular
 Heterotrophic
 No cell walls
 Eukaryotic
 Most sexually reproduce

OF
ANIMALS
2 MAIN CATEGORIES:

Invertebrates
No backbone
 Examples:


Vertebrates
Backbone
 Examples

ANIMAL DEVELOPMENT
 Start
off as a single cell
 Cell undergoes mitosis in which each division
results in a doubling of number of cells
 A hollow ball of cells, called the blastula forms
 The blastula begins to fold inwards by a
process called gastrulation
 Gastrulation results in the formation of body
layers called germ layers
GASTRULATION

http://educationportal.com/academy/lesson/gastrulation-and-the3-germ-layers-ectoderm-endodermmesoderm.html
3 GERM LAYERS
1. Ectoderm: forms outer layer of body (becomes
skin, nervous system, feathers, scales, hair, nails)
2. Endoderm: forms inner layer of body (stomach
lining)
3. Mesoderm: forms middle layer (becomes organs of
circulatory, respiratory, excretory & digestive
systems)
 The
more complex an organism is, the more highly
evolved & specialized the tissues and organs
systems are
BODY CAVITIES
“Simple” animals have a pouch-like gut with only
one opening (food enters and wastes leave
through the same opening)
 More complex animals have a gut with two
openings (a mouth & an anus) which allows for
one-way movement of food


Areas of the gut may become specialized for specific
activities (grinding or chewing food, or chemical
digestion, absorption of nutrients and water)
BODY CAVITIES
 Coelom:
fluid-filled space or cavity located
between gut and body wall → where all internal
organs are found
 Allows more room for organs (lungs, heart,
stomach) to grow & develop
 Allows more space for organs to fold/loop/coil –
increases organs surface area to volume ratio
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
 Bilateral
Symmetry: organism has a
left and right side – only 1 vertical cut
through the organism’s centre will
result in 2 (relatively) identical halves
 Symmetry of an organism is related to
its development and how much an
organism moves
 Symmetry also provides information
about complexity and evolutionary
development of an organism
 Bilateral symmetry is found in more
complex and more highly developed
organisms
INVERTEBRATES WITH RADIAL
SYMMETRY
Usually sessile (sedentary) or move very little
since they do not have a head (there isn’t one
region which always leads)
 Usually dependent on environment to bring them
food & to help them reproduce

INVERTEBRATES WITH BILATERAL
SYMMETRY
 Are
usually motile
 Usually show cephalization (developed
head) in the anterior end
Since animals usually move with anterior end
first, this end usually contains eyes & sensory
organs – allows organisms to detect its
environment as it moves (ie. Locate food,
danger, changes in the environment)
 Even though it may appear more advanced to
have cephalization, not all organisms need to
have a head in order to survive.

BODY REGIONS
Anterior = front end
 Posterior = back end
 Dorsal = upper side (backside)
 Ventral = lower side (belly side)

Dorsal
Anterior
Posterior
Ventral