Introduction to the Animal Kingdom

Ms. Moore1/30/13

What is an animal?• Characteristics:

▫Multicellular: have many cells▫Eukaryotic: cells contain nucleus▫Heterotrophs: get their energy from something

else▫Cells lack cell walls

• Animal population:▫95% invertebrates: do not have a

backbone/vertebral column▫5% vertebrates: have a backbone

http://www.tapirback.com/tapirgal/gifts/friends/default.htm

What animals do to survive

•Feeding: most animals cannot absorb food, they ingest it▫Herbivores: eat plants▫Carnivores: eat other animals▫Omnivores: eat plants and animals▫Detritivores: eat decaying plant and

animals material▫Symbiotic relationship: two organisms live

together and one or both are supported by this relationship

• Respiration: take in oxygen and give off carbon dioxide▫Lungs▫Gills▫Diffusion

• Circulation: transport of oxygen, nutrient molecules, and waste products▫Diffusion in thin celled animals▫Complex systems in larger animals

• Excretion: ammonia is a waste product that is a by product of cellular metabolism—it must leave the body so it doesn’t pile up and become toxic▫Simple cells▫System: kidneys

• Response: organisms respond to their environment ▫Nerve cells▫Receptor cells▫Nervous systems

• Movement: not all animals move from place to place, but all have some kind of muscle that shortens in response to a stimulus▫Even sedentary animals feed and pump water

throughout their bodies

• Reproduction▫sexual reproduction increases genetic variety in a

population and helps species evolve when their environment changes

▫Asexual reproduction: animals reproduce rapidly

Cell Specialization

•All complex animals have▫High levels of cell specialization▫Internal body organization

•Other characteristics▫Bilateral symmetry▫Front end/head with sense organs

Early Development• All sexually-reproducing animals begin as a zygote

(fertilized egg). The zygote undergoes divisions to form a blastula (hollow ball of cells).

• Blastula folds in on itself to form an opening called a blastopore.▫If blastopore forms a mouth, the organism is called a

protostome. invertebrates

▫If blastopore forms an anus, the organism is called a deuterostome. vertebrates

(p. 661 has awesome illustration of this)

•Most embryo cells differentiate into 3 germ layers▫Endoderm: develops digestive tract and

respiratory system▫Mesoderm: gives rise to muscles and much

of circulatory system▫Ectoderm: gives rise to sense organs,

nerves, and outer layer of skin

Body Symmetry

•With the exception of sponges, all animals have some type of symmetry▫Radial symmetry: an organism is equally

divided in any direction on a plane▫Bilateral symmetry: body is equally divided

in half Anterior/Posterior Dorsal/Ventral

Cephalization

•Found in bilaterals

•Cephalization: concentration of sense organs at the anterior (front) end of the body

•Information is collected by this end because the organism travels forward

Body Cavity Formation

•Provides a space for organs to be suspended and not touching our muscles or other tissues

•Keeps organs from getting twisted with body’s movements

Quick Lab

•Work with 1 partner to create a model representing radial and bilateral symmetry.▫Label anterior, posterior, dorsal, and

ventral when appropriate.

•Exit Ticket: Which type of body symmetry is more suited to walking forward? WHY?