Animal Kingdom
Invertebrates
Animals without a backbone
All organisms in this kingdom have
these common characteristics:
•Multicellular
•Eukaryotes
•No cell wall- unlike fungi,
plants, bacteria
•Heterotrophs– consumers
•Have Specialized Cells- unlike
protists
Body Plans
Asymmetry – no
symmetry
Radial symmetry
- can cut in equal
halves-more than
one way
Bilateral symmetry
– allows for
development of
brain region in a
central location
(head)
Asymmetrical body
Radial Symmetry
Bilateral Symmetry
Bilateral Symmetry
•Has a head (dorsal) end and a Tail (caudal) end.
•Has a right and left side.
•Has a front (anterior) and a Back (posterior) side.
Development of Organisms
Develop from a single cell, the zygote
Mitosis forms new cell in a process called
cleavage
A hollow ball of cells are formed called a
blastula
Gastrulation is the folding in of the blastula
to form two layers
These two layers are the ectoderm and the
Endoderm.
Development
Ectoderm develops into skin and nervous
tissue
Endoderm develops into the lining of the
digestive tract and organs associated
with digestion
In some animals the gastrula forms a
mesoderm
Mesoderm is the third layer and develops
into muscles, circulatory, excretory, and
respiratory systems
Body Cavities
Acoelom- do not have a body cavity,
organs are imbedded in tissues
Pseudocoelom -(partial) a body cavity
partly lined with mesoderm
Coelom- a body cavity that provides
space for the development of internal
organs (something for muscles to push
against to move)
 PHYLUM:
PORIFERA
 Pore-bearing animals
 sponges
Phylum Porifera
Porifera
Characteristics:
Sessile - do not move
Asymmetrical
No tissue (Only organized cells – 2
cell layers)
No mouth
Hermaphrodite
Body plan: 2 cell layers
skeleton of spicules (spines)
Sexual – release sperm into water (external
fertilization very common in aquatic animals)
Hermaphroditism – sponges have sperm AND
eggs to increase the odds of reproduction
Offspring can swim to a new location
Asexual fragmentation also possible
PHYLUM: Cnidarians
Stinging cell animals
Jellyfish, coral, sea anemonea
Evolution of Radial Symmetry
Extends tentacles equally in all directions
(increase food uptake)
Characteristics:
•Stinging cells
•3 cell layers
•Mouth, gut for digestion
•Nerve net throughout body
•2 body forms
Reproduces sexually and asexually
Skeleton-none present, but dead
coral remains are calcium carbonate
PHTLUM: Platyhelminthes
The flatworms
Planeria, tapeworms, flukes
Characteristics:
No coelom – Why? Many are
parasitic
O2 and sugar are absorbed in
host’s intestine
Bilateral symmetry
Reproduction-most are
hermaphrodites
Tapeworm
PHYLUM: Nematoda
Roundworms
hookworm, heartworms
Characteristics:
•Smooth, non-segmented body
•Pseudocoelom (moves more)
•Can burrow through skin (walking
around barefoot)
•Also enters through
contaminated food
•Bilateral symmetry
•Complete digestive system with
mouth and anus
•Sexual reproduction. Sexes
seperate
•Oxygen enters by diffusion
Hookworms,
Pinworms,
Tapeworms that
were removed from a
Brazilian boy treated
on a Rockefeller
foundation mission
(early 1900’s)
These parasites still
affect people all
over the globe.
Roundworms
Dirofilaria is a roundworm that causes
heartworm disease in dogs
PHYLUM: Annelid Segmented Worms
earthworms, leeches, sea slugs
Characteristics:
•Bilateral symmetry
•Full Coelom (full range of motion,
complex organs inside)
•Complete digestion system
•Most are hermaphrodites with sexual
reproduction
•Gets O2 directly from moist
skin
•closed circulatory system with 5
hearts to deliver
Food – blood (leeches), or dirt
(earthworms)
Swallow dirt, filter out food
Loosen soil, helps to aerate
soil for plants
Also fertilizes plants with
castings (poop)
PHYLUM:Mollusks
Head-footed animals
Clams, snails, squid, oysters, octopus
Characteristics:
•Bilateral symmetry
•Getting food – filter feeders (clams),
grazers (snails), predators (slugs)
•Getting O2 – gills in aquatic mollusks,
primitive lung in snails
•Open or closed circulatory system
PHYLUM:Arthropods
Jointed legged animals
Spiders, insects, crabs, millipeds
Four main classes within this HUGE
phylum:
1. Arachnids
2. Crustaceans
3. Centipedes / millipedes
4. Insects
PHYLUM: Echinoderm
Spiny Skinned Animal
Star fish, sea urchin, sea cucumber
Characteristics:
•Radial symmetry
•Mouth on ventral side of body
•Marine
•Reproduction: sexes separate,
external, forms pelagic (free-floating)
larvae
•Water vascular system with tube-feet
•Can regenerate lost body parts