InvertebratesInvertebrates

DefinitionDefinition

Sub-Kingdom of AnimalsSub-Kingdom of Animals

Animals that do not have Animals that do not have a backbone at a backbone at anytime during their anytime during their developmentdevelopment

There are 8 major phyla There are 8 major phyla of invertebratesof invertebrates

PoriferaPoriferaSponges – “Pore Bearer”Sponges – “Pore Bearer”

Characteristics:Characteristics:*Two cell layers *Two cell layers

with one body with one body openingopening

* Most are * Most are asymmetricalasymmetrical* Sessile (Do not * Sessile (Do not

move-Stuck in move-Stuck in one place)one place)

* Filter Feeders* Filter Feeders

CnidariansCnidarians

CharacteristicsCharacteristics

* Two cell layers with one * Two cell layers with one body openingbody opening

* Most radial symmetry* Most radial symmetry* Have stinging cells * Have stinging cells

(nematocysts) (nematocysts) * Two life stages, polyp * Two life stages, polyp

(baby) and medusa (adult)(baby) and medusa (adult)

ExamplesExamples* Jellyfish, corals, sea * Jellyfish, corals, sea

anemones, hydrasanemones, hydras

PlatyhelminthesPlatyhelminthesFlatwormsFlatworms

CharacteristicsCharacteristics* Bilateral symmetry* Bilateral symmetry* Flattened bodies* Flattened bodies* One body opening* One body opening* Slightly developed * Slightly developed

nervous and sensory nervous and sensory systemssystems

Examples:Examples:* Tapeworms, flukes, * Tapeworms, flukes,

planariansplanarians

Tapeworms in BodyTapeworms in Body

NematodaNematodaRoundwormsRoundworms

CharacteristicsCharacteristics

* Tubelike digestive * Tubelike digestive system with 2 body system with 2 body openingsopenings

* Many parasitic—* Many parasitic—hurt other hurt other organismsorganisms

* Sensory eyespots* Sensory eyespots

Heartworm—A Parasitic Heartworm—A Parasitic RoundwormRoundworm

MolluscaMolluscaMollusksMollusks

CharacteristicsCharacteristics* Bilateral symmetry* Bilateral symmetry* Body cavity for organs* Body cavity for organs* 2 Body openings with * 2 Body openings with

completed digestive completed digestive tracttract

* Mantle (surrounds * Mantle (surrounds internal organs; internal organs; secretes shell in most secretes shell in most mollusks) mollusks)

* Muscular foot for * Muscular foot for movementmovement

Mollusca ContinuedMollusca Continued

* Live in water * Live in water

Examples:Examples:

* Gastropods (1 Shell)* Gastropods (1 Shell)

SnailsSnails

* Bivalves (2 Shells)* Bivalves (2 Shells)

ClamsClams

* Cephalopods (head-* Cephalopods (head-footed)footed)

Octopi, SquidOctopi, Squid

AnnelidaAnnelidaSegmented WormsSegmented Worms

Characterisitcs:Characterisitcs:* Bilateral Symmetry* Bilateral Symmetry* * CoelomCoelom and two body and two body

openingsopenings• Segmentation—Segmentation—

provides for great provides for great flexibilityflexibility

• Have Setae (hairs)Have Setae (hairs)

Examples:Examples:* Leeches, earthworms, * Leeches, earthworms,

bristlewormsbristleworms

ArthropodsArthropods

Characteristics:Characteristics:* Bilateral Symmetry* Bilateral Symmetry* Exoskeletons—tough * Exoskeletons—tough

outer coverings that outer coverings that protects and provides protects and provides supportsupport

*Jointed appendages*Jointed appendages* Some have fused * Some have fused

segmentssegmentsExamples:Examples:* Insects, spiders, crabs, * Insects, spiders, crabs,

centipedescentipedes

EchinodermataEchinodermata

Characteristics:Characteristics:* Radial Symmetry* Radial Symmetry

(Larvae have radial)(Larvae have radial)* Endoskeleton—internal * Endoskeleton—internal

skeleton for supportskeleton for support* Rough exterior that looks * Rough exterior that looks

like a “spiny skin”like a “spiny skin”* Water vascular system for * Water vascular system for

movement—changes movement—changes pressure which creates a pressure which creates a suction on “feet”suction on “feet”

Examples:Examples:* Sea Stars, Starfish, Sand * Sea Stars, Starfish, Sand

DollarsDollars

Invertebrate ChordateInvertebrate Chordate

Characteristics:Characteristics:* Chordates—Have a * Chordates—Have a

notochord, dorsal notochord, dorsal nerve cord, gill slits, nerve cord, gill slits, muscle blocks during muscle blocks during all or part of life cycleall or part of life cycle

* Bilateral Symmetry* Bilateral Symmetry* Most advanced of * Most advanced of

invertebratesinvertebratesExamples:Examples:* Tunicates (Sea * Tunicates (Sea

squirts), lancetssquirts), lancets