Introduction to the Animal Kingdom Ms. Moore 1/30/13

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

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?