Introduction to animals

Introduction Introduction to Animalsto Animals

TraitsTraitsWHAT IS AN ANIMAL ? ? ?

Characteristics of Characteristics of AnimalsAnimals•ALL ANIMALS :

•Are Multicellular (Metazoans)•Are Eukaryotes (cells with

nucleus & organelles)•Are Ingestive Heterotrophs

(take in food and internally digest it)

•Have cells that lack a Cell Wall

Lions Feeding Lions Feeding (HETEROTROPHIC)(HETEROTROPHIC)

Have more than one Eukaryotic Cell and those

Cells lack a Wall

ANIMAL CELLPLANT CELL

Support SystemsSupport Systems• Have some type of skeletal/fluid structural

support• Endoskeleton inside and made of cartilage &/or

bone• Exoskeletons found in arthropods

– Cover the outside of the body– Must be molted making animal vulnerable to

predators

Cicada Molting Cicada Molting ExoskeletonExoskeleton

Support SystemsSupport Systems

• Worms and echinoderms (starfish) have fluid-filled internal cavities giving them support

• Called hydrostatic skeletons

MostMost Animals Exhibit Animals Exhibit MovementMovement

• Animals such as sponges may be sessile (attached & non-moving)

• Animals that move very little are said to be sedentary (clam)

• Animals that can move are motile.• Have muscular tissue to provide

energy for movement

SESSILE SEDENTARY

MOTILE

Sponge Chiton

Cheetah

Reproduction in Reproduction in AnimalsAnimals

•Pretty much all animals are capable of sexual reproduction

•Some animals like sponges and earthworms are hermaphrodites producing both eggs and sperm

•Hermaphrodites may exchange sperm and NOT fertilize their own eggs

Leeches Exchange Leeches Exchange Sperm During Sexual Sperm During Sexual

ReproductionReproduction

Mating

leech

Levels of OrganizationLevels of Organization• Sponges are the ONLY

animals that have just the cellular level of organization

• All other animals show these levels – cell tissue organ system

• Cells may specialize (take on different shapes and functions)

• Cells are held together by cell junctions to form tissues

• Various tissues can build organs

Levels of Organization

Atom

Molecule or

compound

Organelle

CELLLevels of Levels of OrganizationOrganization

TissueOrga

nOrgan syste

mOrganism

Life begins

Surfaces• Dorsal – back or upper surface• Ventral – belly or lower surface• Anterior – head or front end• Posterior – tail or hind end opposite the

head• Oral surface – where the mouth is

located (underside of echinoderms) • Aboral surface – opposite the mouth

(top side of echinoderms)

DORSAL

VENTRAL

Surfaces (Most Surfaces (Most Animals)Animals)

ANTERIOR POSTERIOR

Symmetry

Body SymmetryBody Symmetry

Body SymmetryBody Symmetry• 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)

Body SymmetryBody Symmetry

•Radial symmetry occurs when body parts are arranged around a central point like spokes on a wheel (echinoderms)

•Most animals with radial symmetry are sessile (attached) or sedentary (move very little)

Body SymmetryBody Symmetry

•Bilateral symmetry occurs when animals can be divided into equal halves along a single plane

•Organisms will have right and left sides that are mirror images of each other

•More complex type of symmetry

Body SymmetryBody Symmetry

• Animals with bilateral symmetry are usually motile

• Animals have an anterior and posterior ends

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

SegmentationSegmentation• Occurs whenever animal bodies

are divided into repeating units or segments.

• Found in more complex animals• Earthworms show external

segmentation.• Humans show internal

segmentation (backbone)• Segments may fuse

(cephalothorax)

Segmentation

SegmentationSegmentation• Occurs whenever animal bodies

are divided into repeating units or segments

• Found in more complex animals• Earthworms show external

segmentation• Humans show internal

segmentation (backbone)• Segments may fuse

(cephalothorax)

ANIMAL Phyla In Unit 5 we look at include

Phylum – PoriferaPhylum - Cnidaria (“NYDARIA”)Phylum – Platyhelminthes

Phylum – NematodaPhylum - Annelida

PHYLUM PORIFERA(Sponges)

PHYLUM CNIDARIA (Jelly Fish, Sea Anemones and Corral

PHYLUM - PLATYHELMINTHES

Intestinal Tapeworm

Roundworms (Nematoda) Roundworms (Nematoda) and Segmented Worms and Segmented Worms

(Annelida)(Annelida)

Nematode Leech (segmented worm)