Animal Characteristics

1. Eukaryotes

2. Multicellular

3. No cell walls or chloroplasts

4. Heterotrophic

5. Many types of movement

a. Sessile: don’t move (barnacles)

b. Mobile early, sessile adults (coral)

c. Sessile larvae, mobile adults (jellyfish)

d. Mobile: able to move

6. 1st evolved in water-more food than on land-needed to expend less energy

7. Ingest: digest food w/in body-digestive system is specialized

to diet8. Cells specialized into tissues

& organs to carry out specific functions

Development

1. Fertilization: when egg & sperm join to form a zygote

-occurs only during sexual reproduction

2. Cell division occurs by mitosis (cleavage)-embryo: mass of dividing & developing cells

-org. at an early stage of growth/development

-blastula: hollow ball of cells filled w/ fluid

-humans-5 days after fertilization

http://www.ocean.udel.edu/newscenter/embryo.jpg

3. Gastrulation: cells on 1 side of the blastula push inward

-gastrula: structure of 2 layers w/ an opening at 1 end

-layers formed in gastrulaa. ectoderm: outer cell layer

that will develop into skin & nervous tissue

b. endoderm: inner cell layer that will develop into digestive system

c. mesoderm: middle layer that may form later, will develop into all other systems

-2 types of gastrulation a. Protostomes: opening of

gastrula develops into mouth-snails, earthworms,

insectsb. Deuterostomes: mouth

doesn’t form from gastrula opening-starfish, fish, amphibians, birds, reptiles, &

mammals

4. Growth & Development

-cells differentiate & become specialized for their specific function

5. Adulthood

-org. reach sexual maturity, reproduce, & process begins again

Symmetry

-arrangement of body structures

-allows for specific movement

1. Asymmetry: not symmetrical, irregular body shape

-usually sessile

2. Radial symmetry: can be divided into equal halves by multiple plans thru center

-allows org. to detect & capture prey from many angles

3. Bilateral symmetry: can be divided into right & left halves along 1 plane

-more effective movement

Body plans

-develop 3 embryonic layers (ecto/meso/endoderm)

-may have fluid-filled body cavity that allows for increased size

Types

a. Acoelomates: no body cavity

-flatworms

-solid, compact body

b. Pseudocoelomates: space between endoderm & mesoderm filled w/ fluid

-roundworms

-allows for more effective movement

-1-way digestive tract

c. Coelomates: fluid-filled space completely lined w/ mesoderm

-one-way digestive tract

-organs cushioned/protected

-efficient movement

Protection & Support

1. Shells

2. Exoskeleton: hard outer covering that provides support for body framework-protect soft areas, prevent water loss-secreted by skin-place for muscles to attach-usually found in invertebrates:

animal w/out a backbone

3. Endoskeleton: internal skeleton covered by cells that supports body

-protects internal organs

-muscle attachment

-e.g. -invertebrates-sea stars-

made of calcium carbonate

-Vertebrate: animals w/ endoskeleton & a backbone (bilateral sym.)-shark-made of cartilage-bony fish mammals-

made of bone