Introduction to animals

Introduction to Animals – Ch.

32

The Nature of AnimalsSection 32.1

Classification:●95-98% of animals are invertebrates

●Without a backbone●2-5% of animals are vertebrates

●With a backbone

AnimalTraits

Characteristics:

All animals are:1. Multicellular2. Eukaryotic3. Ingestive heterotrophs4. Lacking in cell walls5. Sexually reproductive6. Able to move

1. Multicellular Organization●Cell specialization: the

evolutionary adaptation of a cell for a particular function

●Tissue: group of similar cells that perform a common function

●Cell junctions: connections between cells that hold them together as a unit

Atom

Molecule or

compound

Organelle

CELLLevels of Organization

TissueOrga

nOrga

n syste

m

Organism

Life begins

2. Eukaryotic cells

3. Ingestive Heterotrophy●Getting complex organic

compounds (carbon) from sources other than the sun

●Ingestion: taking in food usually in the form of an other organism

●Digestion: the body’s process of extracting organic molecules from food

Lions Feeding (Ingestion)

4. Lack of cell walls

5. Sexual Reproduction & Development●Hermaphrodites: producing both eggs

and sperm●Examples: worms & sponges●Most do NOT fertilize own eggs

●Why not?

●Zygote: diploid cell that results from the fusion of two haploid gametes●Undergoes differentiation (cells

becoming specialized to perform a specific function)

Mating and

Mating Behaviors

Beetles Mating

Male

Female

Young

Courtship

Leeches Exchange Sperm During Mating

Mating

leech

Parthenogenesis:●Females of some animals produce

eggs, but the eggs develop without being fertilized!●New offspring will be all female

●Example animals: some fishes, several kinds of insects, and a few species of frogs and lizards

Parthenogenesis in the Komodo Dragon

Video!

6. Movement●Sessile: attached & non-moving

●sponges●Sedentary: move very little

●clam●Motile: animals that can move

●humans

●Ability to move depends upon interaction between nervous tissue and muscle tissues●Neurons: cells of nervous tissue

SESSILE SEDENTARY

MOTILE

SpongeChiton

Cheetah

Origin of Animals:●Animals came about in the water

●Evolved from colonial protists:●Each organism had its own function (for the

colony) much like each cell of the animal body has its own function (for the organism)

Video

Body Structure:●Symmetry is the

arrangement of body parts around a central plane or axis

●Asymmetry occurs when the body can’t be divided into similar sections● sponges

Radial symmetry●when body parts are arranged

around a central point ●like spokes on a wheel ●echinoderms

●Most animals are sessile (attached) or sedentary (move very little)

Bilateral symmetry●when animals can be divided into

equal halves along a single plane●right and left sides that are mirror images of each other

●are usually motile

●Show cephalization●concentration of sensory organs on the head (anterior) end

What type of symmetry is this?

Segmentation●When an animal body is composed of a series

of repeating similar units●Example: earthworm (annelid)

●Segments may look different & have different functions●Example: insects & crustaceans (arthropods)

Anatomical Terms:Dorsal: back surface of animal

Ventral: underside of animalAnterior: front end of animalPosterior: rear end of animalLateral: sides of animalMedial: along midline of animal

Proximal: near toDistal: away from

Label the parts: