Invertebrates

THE THE ANIMAL ANIMAL

KINGDOMKINGDOM

Characteristics of Characteristics of AnimalsAnimals

Basic CharacteristicsBasic Characteristics

EukaryoticEukaryotic MulticellularMulticellular

Cell specialization?Cell specialization?

HeterotrophicHeterotrophic Move to food vs. catch Move to food vs. catch

foodfood

No cell wallsNo cell walls Cell mobilityCell mobility

LocomotionLocomotion

InvertebratesInvertebrates

34 phyla34 phyla We’ll cover about elevenWe’ll cover about eleven

No backboneNo backbone Land? Small (no support)Land? Small (no support) Ocean? Small or largeOcean? Small or large

Largest structure on the Largest structure on the planet built by animals?planet built by animals?

VertebratesVertebrates

1 phylum1 phylum

Internal skeletonInternal skeleton CraniumCranium BackboneBackbone Nerve chordNerve chord Larger sizeLarger size

Animal BehaviorsAnimal Behaviors

FeedingFeeding RespirationRespiration CirculationCirculation GrowthGrowth ExcretionExcretion ResponseResponse ReproductionReproduction

Animal Body SystemsAnimal Body Systems

SupportSupport

Provides framework Provides framework for movementfor movement

Hydrostatic skeletonHydrostatic skeleton ExoskeletonExoskeleton EndoskeletonEndoskeleton

Digestion and ExcretionDigestion and Excretion Extracts energyExtracts energy

None in single-celled None in single-celled organismsorganisms

Gastrovascular cavity Gastrovascular cavity (one opening)(one opening)

Digestive tract (two Digestive tract (two openings)openings)

Excretion must remove Excretion must remove wastes without wasting wastes without wasting resourcesresources

Nervous SystemNervous System

Carries information; Carries information; coordinates behaviorscoordinates behaviors

Nerve netNerve net GangliaGanglia BrainBrain Special sensory Special sensory

cells/organscells/organs

Respiration and CirculationRespiration and Circulation

Lungs, gills, etc.Lungs, gills, etc.

Larger organisms Larger organisms require circulatory require circulatory systemssystems

Open vs. closed Open vs. closed circulatory systemscirculatory systems

ReproductionReproduction

AsexualAsexual Examples: budding, Examples: budding,

new limbs, etc.new limbs, etc.

SexualSexual Union of gametes Union of gametes

produced in sex produced in sex organsorgans

Some organisms use Some organisms use bothboth

Evolutionary TrendsEvolutionary Trends

Directional TerminologyDirectional Terminology

Anterior / PosteriorAnterior / Posterior

Dorsal / VentralDorsal / Ventral

LateralLateral

Proximal / DistalProximal / Distal

Cells and TissuesCells and Tissues

Cells Cells

Tissues Tissues

Organs Organs

Organ Systems Organ Systems

Organisms Organisms

PopulationsPopulations

Tissues: groups of Tissues: groups of similarly-specialized similarly-specialized cellscells

SymmetrySymmetry

No symmetryNo symmetry

Radial SymmetryRadial Symmetry

Pentamerous SymmetryPentamerous Symmetry

Bilateral SymmetryBilateral Symmetry

Bilateral SymmetryBilateral Symmetry

CephalizationCephalization

Anterior Anterior grouping of grouping of nerves and nerves and sensory sensory structures structures

Body SegmentationBody Segmentation

Repeating, similar unitsRepeating, similar units

In most complex animals, In most complex animals, segmentation only appears during segmentation only appears during early developmentearly development

Evolutionary benefitsEvolutionary benefits

Most segments serve a specific Most segments serve a specific purposepurpose

Mobility and flexibilityMobility and flexibility

Zygote – union of Zygote – union of sperm/eggsperm/egg

Cleavage – division of Cleavage – division of zygote cellszygote cells

Blastula – hollow ball of Blastula – hollow ball of embryonic cellsembryonic cells

Blastopore – “pocket” Blastopore – “pocket” that forms in cellsthat forms in cells

Embryonic DevelopmentEmbryonic Development

Embryonic DevelopmentEmbryonic Development

Gut develops in one of Gut develops in one of two ways:two ways:

Protostomes – Protostomes – blastopore becomes blastopore becomes mouthmouth

Deuterostomes – Deuterostomes – blastopore becomes blastopore becomes anusanus

Embryonic DevelopmentEmbryonic Development Three embryonic tissue layers Three embryonic tissue layers

in most organisms, which give in most organisms, which give rise to specific tissues:rise to specific tissues:

Ectoderm (skin, nervous Ectoderm (skin, nervous system)system)

Mesoderm (skeleton, muscles, Mesoderm (skeleton, muscles, circulatory system)circulatory system)

Endoderm (glands, liver, gut, Endoderm (glands, liver, gut, lungs)lungs)

CoelomCoelom

Internal body cavity Internal body cavity that houses organsthat houses organs

Cushions organs and Cushions organs and assists with assists with movementmovement

Some organisms are Some organisms are considered considered “pseudocoelomates”“pseudocoelomates”

In Review: Complex AnimalsIn Review: Complex Animals

Cell specializationCell specialization CephalizationCephalization Bilateral SymmetryBilateral Symmetry SegmentationSegmentation DeuterostomesDeuterostomes Three tissue layersThree tissue layers CoelomateCoelomate



What to Remember About Each PhylumWhat to Remember About Each Phylum

Symmetry?Symmetry?

Cephalization?Cephalization?

Nervous, circulatory, skeletal, Nervous, circulatory, skeletal, digestive, and other systemsdigestive, and other systems

Specific characteristicsSpecific characteristics

ExamplesExamples

Phylum PoriferaPhylum Porifera

PoriferaPorifera

““sponges”sponges” Feed, excrete and Feed, excrete and

undergo respiration undergo respiration by passing water by passing water through their through their bodiesbodies

ChoanocytesChoanocytes OsculumOsculum

PoriferaPorifera

No symmetryNo symmetry No nervous systemNo nervous system No extracellular digestionNo extracellular digestion Size ranges from Size ranges from

centimeters to meterscentimeters to meters Can reproduce sexually or Can reproduce sexually or

asexually (budding)asexually (budding) Most are hermaphroditicMost are hermaphroditic

PoriferaPorifera Cells not organized into tissuesCells not organized into tissues

Classified according to their Classified according to their skeleton (of spicules or spongin)skeleton (of spicules or spongin)

PoriferaPorifera

PoriferaPorifera

Mutualistic relationships Mutualistic relationships with other organisms, with other organisms, like this sponge crablike this sponge crab

Phylum CnidariaPhylum Cnidaria

CnidariaCnidaria

jellyfish, hydras, sea jellyfish, hydras, sea anemones, coralsanemones, corals

CarnivorousCarnivorous Radial symmetryRadial symmetry Gastrovascular cavity Gastrovascular cavity

(one opening)(one opening)

Cnidaria Two possible body forms:

Medusa (free-floating, sexually reproducing)

Polyp (sedentary, asexual)

Two tissue layers (epidermis and gastrodermis) with jelly-like mesoglea in-between

CnidariaCnidaria

Stinging cells called Stinging cells called cnidocytescnidocytes

Cnidocytes contain Cnidocytes contain nematocysts, poison-nematocysts, poison-filled stingersfilled stingers

Hydrostatic skeletonHydrostatic skeleton Nerve NetNerve Net Movement by Movement by

muscular contractionmuscular contraction

CnidariaCnidaria

Mutualistic relationship Mutualistic relationship with algaewith algae Coral bleachingCoral bleaching

FlatwormsFlatworms

Phylum PlatyhelminthesPhylum Platyhelminthes

PlatyhelminthesPlatyhelminthes

Soft, flattened wormsSoft, flattened worms Internal organsInternal organs Bilateral symmetryBilateral symmetry CephalizationCephalization No coelomNo coelom Muscle tissuesMuscle tissues


Feeding: carnivores, Feeding: carnivores, scavengers, parasitesscavengers, parasites

Mouth found on undersideMouth found on underside Invert pharynx to feedInvert pharynx to feed Exception: Tapeworms Exception: Tapeworms

absorb nutrients through absorb nutrients through the body wallthe body wall

No need for circulatory No need for circulatory systemsystem



Much more complex Much more complex nervous system than nervous system than CnidariaCnidaria

More advanced More advanced reproductive systemreproductive system

Planaria are “cross-eyed” Planaria are “cross-eyed” flatworms that live in flatworms that live in nearby streamsnearby streams

Eyespots sense lightEyespots sense light

Platyhelminthes

Example: Schistosoma Cause schistosomiasis (second most devastating

parasitic disease – 200,000,000 infected) Larvae bore through skin and mature Females lay eggs in blood vessals Eggs block blood vessals, damaging organs Eggs deposited in feces Larvae infect snail and reproduce asexually

RoundwormsRoundworms

Phylum NematodaPhylum Nematoda

NematodaNematoda

Two openings – mouth Two openings – mouth and anusand anus

Simplest animals with Simplest animals with coelom (actually a coelom (actually a pseudocoelom), allowing pseudocoelom), allowing better coordination of better coordination of musclesmuscles

Some carnivorous, some, Some carnivorous, some, detritivores, some detritivores, some parasiticparasitic

NematodaNematoda

Separate sexesSeparate sexes

Internal fluid acts Internal fluid acts as a simple as a simple circulatory systemcirculatory system

NematodaNematoda

Although less Although less common than common than free-living free-living nematodes, nematodes, some are some are parasitic and parasitic and cause diseases cause diseases in humansin humans

Segmented WormsSegmented Worms

Phylum AnnelidaPhylum Annelida

AnnelidaAnnelida

70% live in water70% live in water Includes most common Includes most common

earthworms and leechesearthworms and leeches Segmented: many organs Segmented: many organs

repeat in each segmentrepeat in each segment True coelomTrue coelom

AnnelidaAnnelida

Many types of feeding: Many types of feeding: filter feeders, carnivores, filter feeders, carnivores, parasitesparasites

Closed circulatory system Closed circulatory system with hearts and blood with hearts and blood vesselsvessels

On land, annelids On land, annelids breathe through their breathe through their skin, like other wormsskin, like other worms

AnnelidaAnnelida

Complex gutComplex gut

Ganglia Ganglia (primitive brain) (primitive brain) and nerve chordand nerve chord

AnnelidaAnnelida

Importance:Importance: Leeches once used to Leeches once used to

prevent swelling after prevent swelling after surgery.surgery.

Earthworms help Earthworms help organic matter organic matter decompose and aerate decompose and aerate soil.soil.

MollusksMollusks

Phylum MolluscaPhylum Mollusca

Phylum MolluscaPhylum Mollusca

Kinds of MollusksKinds of Mollusks

snails, slugs, clams, snails, slugs, clams, oysters, mussels, scallops, oysters, mussels, scallops, squids, octopi, cuttlefishessquids, octopi, cuttlefishes

Characteristics of MollusksCharacteristics of Mollusks

Coelom!Coelom! Bilateral symmetryBilateral symmetry Soft-bodied (hydrostatic Soft-bodied (hydrostatic

skel.)skel.) Shell (internal or Shell (internal or

external)external)

Bodies of Mollusks – 4 PartsBodies of Mollusks – 4 Parts

1.1. Foot (muscular, Foot (muscular, used to move or used to move or capture prey)capture prey)

2.2. Mantle (covers Mantle (covers body like a cloak)body like a cloak)

3.3. Shell (created from Shell (created from glands in mantle)glands in mantle)

4.4. Visceral Mass Visceral Mass (contains organs)(contains organs)

Behavior of MollusksBehavior of Mollusks Feeding:Feeding:

Filter feeders (bivalves)Filter feeders (bivalves) Carnivores (cephalopods)Carnivores (cephalopods) Herbivores (gastropods)Herbivores (gastropods)

Toothed organ called Toothed organ called RADULA used to scrape RADULA used to scrape substrate or attack preysubstrate or attack prey

Full digestive tract with Full digestive tract with complex organscomplex organs

Behavior of MollusksBehavior of Mollusks

Nephridia = small tubes Nephridia = small tubes that retain needed that retain needed materials (like a kidney)materials (like a kidney)

3-chambered heart3-chambered heart

Open circulatory system Open circulatory system (except for cephalopods)(except for cephalopods)


Gills located in mantle Gills located in mantle cavitycavity

Thin membrane of Thin membrane of terrestrial snails allows terrestrial snails allows oxygen to pass acrossoxygen to pass across Must be moist!Must be moist!


External fertilization External fertilization (aquatic) or internal (aquatic) or internal fertilization (terrestrial)fertilization (terrestrial)

Trochophore larvae Trochophore larvae drifts through water drifts through water using ciliausing cilia

Mollusk DiversityMollusk Diversity

22ndnd-most abundant -most abundant phylumphylum

Body plan similar but Body plan similar but rearrangedrearranged

Adaptations to foot and Adaptations to foot and shellshell

Class GastropodaClass Gastropoda Snails, slugs, nudibranchsSnails, slugs, nudibranchs

Sizes to 1 mSizes to 1 m

Tentacles with eyesTentacles with eyes

Foot adapted for Foot adapted for locomotionlocomotion

Mucus secretionsMucus secretions

Class CephalopodaClass Cephalopoda

squids, octopi, cuttlefishessquids, octopi, cuttlefishes

Tentacles with suction cups or Tentacles with suction cups or hookshooks

Most have no shellMost have no shell

Complex nervous system; highly-Complex nervous system; highly-developed braindeveloped brain

Siphon – hollow tube for Siphon – hollow tube for expelling sea water (locomotion)expelling sea water (locomotion)

Class BivalviaClass Bivalvia

Clams, scallopsClams, scallops Two-part, hinged Two-part, hinged

shellshell SessileSessile Foot used to digFoot used to dig PearlsPearls

ArthropodsArthropods

Phylum ArthropodaPhylum Arthropoda

Kinds of ArthropodsKinds of Arthropods

crabs, shrimps, lobsters, crabs, shrimps, lobsters, barnacles, horseshoe barnacles, horseshoe crabs, spiders, ticks, crabs, spiders, ticks, scorpions, bees, wasps, scorpions, bees, wasps, ants, caterpillars, ants, caterpillars, butterflies, beetles, flies, butterflies, beetles, flies, gnats, cicadas, pillbugs, gnats, cicadas, pillbugs, centipedes, millipedescentipedes, millipedes

Ecology of ArthropodsEcology of Arthropods

73% OF ALL LIVING 73% OF ALL LIVING ANIMAL SPECIES ANIMAL SPECIES ARE INSECTS ARE INSECTS (compared to 4% (compared to 4% vertebrates)vertebrates)

To colonize land, insects To colonize land, insects must solve problems of:must solve problems of: Transportation Water loss prevention Protection

Evolution of ArthropodsEvolution of Arthropods

Over time, arthropods Over time, arthropods evolved fewer body evolved fewer body segments and specialized segments and specialized appendagesappendages

Trilobite – marine Trilobite – marine arthropod ancestorarthropod ancestor

Arthropod Characteristics

Segmented Body Greater number of

segments during larval stage

Adult: Head, thorax, (or cephalothorax) and abdomen

Jointed Appendages Walking legs, antennae,

mouth parts

Arthropod Characteristics

Exoskeleton of chitin Carbohydrate Protection / water loss Thickness varies Unlike mollusk shells,

exoskeletons do not grow (must be molted)

Compound Eyes

Arthropod Body Systems

Respiration Spiracles can be closed (to

prevent water loss) System of tubes called

trachea Book lungs/gills

Open circulatory system

Arthropod Body Systems

Varied mouthparts for eating (fly, beetle, mosquito)

Complete gut Excretion

Malpighian tubules extract water and useful particles before waste is excreted

Internal fertilization and eggs (water loss)

Classification of ArthropodsClassification of Arthropods CrustaceaCrustacea ChelicerataChelicerata HexapodaHexapoda MyriapodaMyriapoda

Chelicerates

Spiders, horseshoe crabs, scorpions, ticks, mites

Specialized appendages for feeding: Chelicerae – fangs/pincers Pedipalps – for grabbing prey

Additionally, 4 pair of walking legs

Chelicerates

Toxins and enzymes used to kill/liquefy food

Spiders have spinnerets, appendages that secrete silk or adhesive

Scorpions have segmented abdomen with a stinger

Crustaceans

Water fleas, barnacles, pill bugs, shrimp, crabs, lobsters

Mandibles for feeding; two pair of antennae

Mostly aquatic

Crustaceans Tiny krill are important in

food chains

Barnacles are sessile (larvae are not) and feathery legs filter food into mouth

Decapods (crabs, shrimp) have chelipeds to grab food and swimmerets used in swimming and reproduction

Hexapods (Insects)

3 segments 3 pair of legs 0, 1, or 2 pair of wings Varied mouthparts with

mandibles

Hexapods

Wings of chitin and strong muscles in exoskeleton

Hexapods

Metamorphosis Complete: egg larva

pupa adult Incomplete: egg

nymph adult

Advantages?

Myriapods

Millipedes and centipedes – highly segmented

Up to 200-300 legs!

EchinodermsEchinoderms

Phylum EchinodermataPhylum Echinodermata

Characteristics of EchinodermsCharacteristics of Echinoderms

Internal (endo)skeletonInternal (endo)skeleton Water vascular system Water vascular system

and tube feetand tube feet Often have pentamerous Often have pentamerous

symmetrysymmetry Types: sea urchins, sand Types: sea urchins, sand

dollars, sea stars, brittle dollars, sea stars, brittle stars, sea cucumbersstars, sea cucumbers


Endoskeleton plates Endoskeleton plates called ossiclescalled ossicles

Spines project outwardSpines project outward

No head/brain (not No head/brain (not cephalized)cephalized)

Nerve ring controls armsNerve ring controls arms

Behavior of EchinodermsBehavior of Echinoderms

Water vascular system Water vascular system functions in feeding, functions in feeding, circulation, respiration, circulation, respiration, and movementand movement

Tube feet (suction cups) Tube feet (suction cups) used to move or grabused to move or grab

Sea stars can pry open Sea stars can pry open clams and mollusksclams and mollusks

Echinoderms – Tube FeetEchinoderms – Tube Feet


Coelom also Coelom also functions as functions as circulatory circulatory systemsystem

Respiration Respiration across skinacross skin

Phylum ChordataPhylum Chordata

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Invertebrates