INVERTEBRATESINVERTEBRATES

CH. 24-27CH. 24-27

Kingdom AnimaliaKingdom AnimaliaMajor Characteristics= eukaryotic, multi-cellular, heterotrophic, lack a cell wall

Invertebrates◦Include 95-97% of all animal species

◦Without a backbone

ExoskeletonExoskeleton

Hard, tough outer covering that provides framework and support

Made of chitin

EndoskeletonEndoskeleton

Internal skeleton

EndodermEndoderm

Inner layer of cells in the gastula

Develops into tissues and organs of the digestive tract

EctodermEctoderm

Outer layer of cells in the gastula

Develops into skin and other body coverings and the nervous system

MesodermMesoderm

Between the endoderm and ectoderm

Develops into skeletons and muscles

CoelomCoelom

Fluid filled cavityProvides open space inside of body

Coelom

SegmentationSegmentation

“put together”Sectionsmultiple body components

CephalizationCephalization

Animals with anterior (head) & posterior (tail)

Tendency to concentrate nervous and sensory organs at the anterior

Development of a specialized head

AsymmetryAsymmetry

Irregular shapeEx. Sponge

Radial symmetryRadial symmetry

Body plan in which parts repeat around an imaginary line drawn through the center

Ex. Cnidarians (jellyfish)

Bilateral SymmetryBilateral Symmetry

Body plan in which left and right sides are identical when an imaginary line is drawn through the center

Ex. Flatworm

SpongesSponges

• Sessile: live entire adult life attached to a single spot • Very simple: no mouth, no organ systems• Rely on the movement of water through their bodies for respiration, circulation, and excretion• Based on their shape, what is their symmetry?

CnidariansCnidarians

• Soft-bodied, carnivorous, stinging tentacles• Simplest animals to have body symmetry and specialized tissues• Based on their shape, what is their symmetry?

Platyhelminthes Platyhelminthes (Flatworms)(Flatworms)

• Soft, flattened worms• Simplest organisms to have cephalization• Based on their shape, what is their symmetry?

Nematoda Nematoda (Roundworms)(Roundworms)

• Unsegmented worms• Have pseudocoeloms and digestive systems with two openings• Many are predators• Some act as parasites that affect humans• Based on their shape, what is their symmetry?

MolluscaMollusca

• Soft-bodied• Usually have an internal or external shell• Based on their shape, what is their symmetry?

Annelida (Segmented Annelida (Segmented Worms)Worms)

• Worms with segmented bodies• Have a true • Based on their shape, what is their symmetry?

ArthropodaArthropoda

Have a segmented body, tough exoskeleton, jointed appendages

Exoskeleton◦Hard, tough outer covering that provides framework and support

◦Made of chitin

Arthropoda - Arthropoda - CrustaceansCrustaceans

• Two pairs of antennae, and two or three body sections• Have chewing mouthparts called mandibles• Based on their shape, what is their symmetry?

Arthropoda – Arachnids Arthropoda – Arachnids (Chelicerates)(Chelicerates)

• Have mouthparts called chelicerae• Two body sections• Nearly all have four pairs of walking legs• Based on their shape, what is their symmetry?

Arthropoda - InsectsArthropoda - Insects

• Jaws• One pair of antennae• Three-part bodies

• head, thorax, abdomen• legs attached to thorax

• Based on their shape, what is their symmetry?

EchinodermataEchinodermata

Sea Cucumber

Sea Urchin

• Spiny skin• Internal skeleton• Water vascular system• Suction-cup “feet” • Based on their shape, what is their symmetry?

Circulatory Circulatory SystemsSystemsOpen circulatory system- a system in which blood vessels from the heart are not contained in blood vessels

Circulatory Circulatory SystemsSystemsClosed circulatory system- a system in which blood is confined to vessels as it moves through the body