ch. 24, section 1

what are the general animal features?

heterotrophic eukaryotes, and multicellular

what does it mean that animals are heterotrophic?

they rely on ingesting other organisms as a food source for energy

how do animals feed?

dependent on their diet, they have specialized mouth functions which perform different functions

how do animals digest?

after obtaining the food they digest either in specialized cells or organs

majority of the animal species are what? and make up what percentage?

90-95% are invertebrates, (most under the category of insects)

invertebrates:

no backbones, have exoskeletons

exoskeletons:

hard or tough outer coverings

vertebrates:

have backbones and endoskeletons

endoskeletons:

internal support structure

what type of habitats are invertebrates and vertebrates found in?

terrestrial, marine, and freshwater ecosystems

describe the animal cell structure:

* no cell walls
* the cells of all animals except sponges are organized into tissues

what are tissues?

a group of cells that are specialized to perform a specific function

what evolved which enabled animals to move in more complex ways than other kingdom’s organisms?

the evolution of nerve and muscle tissues

how do animals reproduce?

most reproduce sexually, some organisms reproduce asexually

what are hermaphrodites?

animals that can produce both sperm and eggs in the same body

what is fertilization?

type of sexual reproduction that occurs when the sperm penetrates the egg to form a fertilized egg called the zygote

when does internal fertilization occur?

when sperm and egg meet inside the animal’s body

when does external fertilization occur?

when sperm and egg meet outside the animal’s body

what are the common methods of asexual reproduction in animals?

budding, fragmentation, and regeneration

budding:

offspring develops as a growth on the parent body

fragmentation:

parent breaks into pieces and each piece can develop into adults

regeneration:

a new organism can regrow from a lost body part if the part contains enough genetic information

state the three stages of early development:

1. zygote undergoes mitosis and a series of cell divisions to form new cells
2. blastula forms as the cells continue to divide
3. gastrula forms

blastula:

fluid-filled ball of cells

gastrula:

a few cells that form a two-layer sac with an opening at one end from the blastula

what is gastrulation?

the forming of the three germ layers (endoderm, ectoderm, and mesoderm)

endoderm:

the inner layer of the gastrula that develops into the digestive organs

ectoderm:

the outer layer of the gastrula that develops into the nervous tissue and the skin

mesoderm:

the third cell layer between the endoderm and ectoderm that forms the muscle, circulatory, excretory, and respiratory system in some animals