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Introduction to the
Animal Kingdom
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Which of these is an “animal”?
Answer: They are all animals!
Characteristics of Animals:
• eukaryotic
• multicellular
• heterotrophic
• lack cell walls
• motile at some point in lifespan
• develop from a blastula early in lifecycle
(hollow ball of cells)
• most reproduce sexually with diploid stage
being dominant stage
Biology = study of life
Physiology = Study
of the functions of
organs
Anatomy = the
structure of the
organism/organs
Zoology = study of
animals
Animal Functions
1.Feeding strategies:
Herbivore = eats plants
Carnivore = eats animals
Omnivore = eats plants and animals
Detritivore = feed on decaying organic
material
Filter Feeders = aquatic animals that
strain food from water
Parasite = lives in or on another organism
(symbiotic relationship)
Scavenger = eats things that have been
killed
2. Respiration:
Take in O2 and
give off CO2
Lungs, gills,
through skin,
simple
diffusion
3. Circulation:
Very small animals rely on diffusion
Larger animals have circulatory system
4. Excretion:
Primary waste product is ammonia
5. Response:
Coordinate their activities with
Receptor cells = sound, light, external stimuli
Nerve cells => nervous system
6. Movement:
* Most animals move
7. Reproduction:
Most reproduce sexually =
genetic diversity
Many invertebrates can
also reproduce asexually to
increase their numbers
rapidly
Body Plan
-how animal’s parts are arranged and
organized; structural blueprint
Body Symmetry:
•Asymmetry - no pattern (corals, sponges)
•Radial Symmetry - shaped like a wheel
(starfish, hydra, jellyfish)
•Bilateral Symmetry has a right and left side
(humans, insects, cats, etc)
Identify the Symmetry
Body Sides
anterior - toward the head
posterior - toward the tail
dorsal - back side
ventral - belly side
Levels of Organization
• In multicellular organisms cells have become
specialized to perform a specific function.
• Groups of specialized cells that work together
are referred to as a tissue – there are 4 animal
tissues (epithelial, connective, muscular,
nervous)
• Groups of tissues can form organs.
• Organs can work together in systems – organ
systems to carry out specific functions
Cephalization - an anterior concentration of
sense organs (to have a head)
*The more complex the animal becomes the more
need for connection of nervous tissue and
receptors at the anterior/head end of body to allow
for rapid movement and processing stimuli
Octopus – member
of the class
Cephalopoda
(head-foot)
Segmentation
-"advanced" animals have body
segments – repeating parts
-different segments like head,
thorax, abdomen have become
specialized for specific function
Embryological Development
Early Development
Animals begin life as a zygote (fertilized egg)
The cells in the zygote divide to form the
BLASTULA - a hollow ball of cells
The blastula pinches inward to form three
GERM LAYERS/body layers.
Give rise to
body systems
i.e. circulatory,
reproductive,
excretory,
muscular
Give rise to gut.
(outer)
(middle)
(inner)
Give rise to outer
skin and nerves.
Coelom – body
cavity
Digestive tract/gut
with one or two
openings; a tube
system
- develops anus first
- develops mouth first
Limbs: legs, flippers and wings
• Animals with bilateral symmetry
and cephalization also tend to have
paired external appendages or limbs
• Limbs may be used for movement,
defense or gathering sensory
information.
e.g. antennae, mouthparts, wings,
gills, legs, fins, arms, and certain
parts of a tail
Animal Kingdom
• Like plants the early ancestor of the animals moved
from water onto land.
• Major evolutionary milestones are marked by
changes in the body plan.
• There are about 35 animal phyla but 9 major ones.
• However one common way to group animals is
whether they have a backbone – vertebrates = 5%
or the absence of a backbone – invertebrates = 95%
Animal Kingdom Phyla
Phylum Porifera
– sponges
Phylum Cnidaria
– sea anemones,
jellyfish, hydra
Phylum Platyhelminthes - flatworms
Free-living Planarian
Parasitic Tapeworm
Phylum Nematoda –
roundworms
Phylum Annelida –
segmented worms
Phylum Mollusca – clams, squid,
snails
Phylum Arthropoda – crustaceans,
insects, spiders
This is the largest phylum in
the animal kingdom and
contains the most number of
species
Phylum Echinodermata - starfish
Phylum Chordata –
includes all vertebrates
Phylum Rotifera –microscopic
aquatic animal
• Soft bodies therefore fossil record weak
• Filter feeders – omnivorous – primary consumers
• Most reproduce by pathogenesis