Invertebrates I:Invertebrates I:Porifera, Cnidaria, Porifera, Cnidaria,

Ctenophora, Ctenophora, Platyhelminthes, AnnelidaPlatyhelminthes, Annelida

Tree Tree of of

LifeLife

Figure CO 7

I.I. Invertebrates - BackgroundInvertebrates - Background

• Kingdom AnimaliaKingdom Animalia• 97% of all animal species are 97% of all animal species are

invertebratesinvertebrates

II.II. Phylum Porifera (Sponges)Phylum Porifera (Sponges)

• Simplest multicellular animalsSimplest multicellular animals

• Most are marine (~9000 species)Most are marine (~9000 species)

• sessilesessile (attached to substrate) (attached to substrate)

• Diversity of shapes, sizes, colors, Diversity of shapes, sizes, colors, habitatshabitats

Fig. 7.2

•Cellular organization-complex aggregation of specialized cells•No true tissues/organs, cells largely independent from each other•No organs, movable parts, appendages•Thus, cells are plastic, can change from one type to another

Shapes:Tiny cups, broad branches, tall vases, encrusting round masses

Body Plan (Structure)- AsymmetricalOstia – water enters-pumped through these poresChoanocytes – Collar cells; line chambers

Beat flagella to pump water through spongetraps food particles

Osculum – water exits (driven by collar cells acting in synch)Spongin – Elastic protein (spongy texture)Spicules – Calcareous or siliceous structures, structural support, discourage predatorsAmebocytes (wandering cells)– Secrete spongin and spicules, transport and store food particles, transform into other types of cells, repair

Simple sponge1 chamber, 1 osculum

Complex spongemany chambers, oscula

II.II. Phylum Porifera (Sponges)-Gr. “pore-bearers”Phylum Porifera (Sponges)-Gr. “pore-bearers”

II.II. Phylum Porifera (Sponges)Phylum Porifera (Sponges)

B.B. FeedingFeeding• Suspension feedersSuspension feeders

• Filter feedersFilter feeders (active suspension feeders) (active suspension feeders)

C.C. ReproductionReproduction• AsexualAsexual• SexualSexual

• Broadcast spawningBroadcast spawning

Water/food IN through ostia

Water-OUTthrough osculum

Fig. 7.3

II. Phylum PoriferaII. Phylum Porifera

3 classes – defined by internal 3 classes – defined by internal skeletonskeleton

Class CalcareaClass Calcarea• CaCOCaCO33 spicules spicules• Shallow tropical watersShallow tropical waters

Class DemospongiaeClass Demospongiae• Bath spongeBath sponge

Class HexactinellidaClass Hexactinellida• Glass sponges, silica spiculesGlass sponges, silica spicules• Deep watersDeep waters

II. Phylum PoriferaII. Phylum Porifera

3 classes – defined by internal skeleton3 classes – defined by internal skeleton

Class CalcareaClass Calcarea• CaCOCaCO33 spicules spicules• Shallow tropical waters (Shallow tropical waters (Leucosolenia, Leucosolenia,

Scypha, Leucandra, LeucillaScypha, Leucandra, Leucilla))• (drawing of (drawing of ScyphaScypha slide) slide)

II. Phylum: PoriferaII. Phylum: Porifera

Class HexactinellidaClass Hexactinellida • Glass sponges, silica spiculesGlass sponges, silica spicules• Deep watersDeep waters• (Euplectella(Euplectella specimen-Venus’s flower specimen-Venus’s flower

basket sponge, spicules slide)basket sponge, spicules slide) Gr. Plecta = lace, this genus is known Gr. Plecta = lace, this genus is known

for lace-like skeleton fused glass for lace-like skeleton fused glass spiculesspicules

II. Phylum: PoriferaII. Phylum: Porifera

Class DemospongiaeClass Demospongiae • Silica, spongin, or both, or lack skeletonSilica, spongin, or both, or lack skeleton• Bath sponge, rounded, spongin fibersBath sponge, rounded, spongin fibers• Encrusting forms, bright colors on rocks and Encrusting forms, bright colors on rocks and

coralscorals

• Boring types, through CaCOBoring types, through CaCO33

• ((SpongiaSpongia specimen, note siliceous specimen, note siliceous spiculation, internal budding) spiculation, internal budding)

III.III. Phylum CnidariaPhylum Cnidaria

• 9000+ species9000+ species• Sea anemonesSea anemones• CoralsCorals• JelliesJellies

A.A. Body PlanBody Plan• Body formsBody forms

• PolypPolyp - sessile - sessile• MedusaMedusa – free floating – free floating

• Radial symmetryRadial symmetry• Oral surfaceOral surface• Aboral surfaceAboral surface

Fig. 7.5

III. Phylum CnidariaIII. Phylum Cnidaria

A.A. Body PlanBody Plan• CnidocytesCnidocytes (stinging cells) (stinging cells)

• DefenseDefense• Prey capturePrey capture

• Contain Contain nematocystsnematocysts (stinging capsule) (stinging capsule)

• Simple nervous systemSimple nervous system• No true organsNo true organs• Single openingSingle opening• Mucus traps foodMucus traps food

www.calacademy.org/research/izg/nematocyst.htm

Undischarged< 0.1 mm

Discharged

coiled thread

fluid

Trigger hair

III. Phylum CnidariaIII. Phylum Cnidaria

B.B. Class Hydrozoa Class Hydrozoa • Polyp formsPolyp forms

• colonial colonial • Specialized polyps (zooids)Specialized polyps (zooids)

• Gastrozooid - FeedingGastrozooid - Feeding• Gonozooid – ReproductionGonozooid – Reproduction• Dactylozooid – Defense (tentacles)Dactylozooid – Defense (tentacles)

• Medusa forms Medusa forms • Siphonophores – Colonial (e.g.- Portugese man Siphonophores – Colonial (e.g.- Portugese man

of war)of war)

Millepora species

III. Phylum Cnidaria, Class HydrozoaIII. Phylum Cnidaria, Class Hydrozoa

gonozooid

gastrozooid

Fig. 7.7

III. Phylum CnidariaIII. Phylum Cnidaria

C.C. Class ScyphozoaClass Scyphozoa• Medusae largeMedusae large

• E.g.E.g. – – Cyanea capillataCyanea capillata (Lion’s Mane) (Lion’s Mane)• Bell > 2 m Bell > 2 m • Tentacles 60+ m Tentacles 60+ m

• Swim by contracting Swim by contracting bellbell rhythmically, pulsating rhythmically, pulsating contractioncontraction

• Stings *Stings *

Desmonema glaciale

Cyanea capillata

III. Phylum CnidariaIII. Phylum Cnidaria

D.D. Class AnthozoaClass Anthozoa• Polyp Polyp • Passive suspension feedersPassive suspension feeders

1.1. Solitary formsSolitary forms• Sea anemonesSea anemones

2.2. Colonial formsColonial formsa.a. CoralsCorals

• Stony corals – branching and massiveStony corals – branching and massive - Some build reefs- Some build reefs• Soft coralsSoft corals

b.b. GorgoniansGorgoniansc.c. Sea pens Sea pens d.d. Sea pansiesSea pansies

Anthopleura xanthogrammica

Branching Corals Doming Corals

Soft Corals

Sea Pen

Sea Pansy

Gorgonians (Sea Whips)

Gorgonians (Sea Fans)

III. Phylum CnidariaIII. Phylum Cnidaria

E.E. Class CubozoaClass Cubozoa• Sea wasps, Box jellyfishSea wasps, Box jellyfish• square bellsquare bell• 4 tentacles or bunches 4 tentacles or bunches • Highly toxicHighly toxic

IV. Phylum Ctenophora (comb jellies)IV. Phylum Ctenophora (comb jellies)

• Biradial symmetryBiradial symmetry• 8 rows of 8 rows of ciliary combs (ctenes)ciliary combs (ctenes)

• swimming swimming • CarnivorousCarnivorous

• Lack nematocystsLack nematocysts• Capture prey with sticky Capture prey with sticky colloblastscolloblasts

• May occur in swarmsMay occur in swarms• Heavy predators Heavy predators

Beroe

Pleurobrachia

V. Phylum PlatyhelminthesV. Phylum Platyhelminthes

• Flatworms - Flatworms - Dorsoventrally flattenedDorsoventrally flattened

• Bilateral symmetryBilateral symmetry

• Simplest organism with Simplest organism with organs and organ organs and organ systemssystems

• Digestive tract has 1 Digestive tract has 1 openingopening

• No circulatory, No circulatory, respiratory, skeletal respiratory, skeletal systemssystems

• Hermaphroditic Hermaphroditic

V. Phylum PlatyhelminthesV. Phylum Platyhelminthes

A. Class Trematoda (Flukes)A. Class Trematoda (Flukes)• ParasiticParasitic – Feed on tissues, blood, gut contents – Feed on tissues, blood, gut contents• Complex life cyclesComplex life cycles

• Adults in vertebrate Adults in vertebrate • Larvae in invertebrates Larvae in invertebrates • Vertebrate eats intermediate hostVertebrate eats intermediate host• Body covered with cuticle resistant to digestionBody covered with cuticle resistant to digestion

B.B. Cestoda (Tapeworms)Cestoda (Tapeworms)• ParasiticParasitic• Live in vertebrate intestines – (uncooked meat)Live in vertebrate intestines – (uncooked meat)

• Head attaches w/4 Head attaches w/4 suckers or hookssuckers or hooks• Gutless – absorb nutrients through body wallGutless – absorb nutrients through body wall• 50 feet!! (sperm whales)50 feet!! (sperm whales)

V. Phylum PlatyhelminthesV. Phylum Platyhelminthes

C. Class TurbellariaC. Class Turbellaria• Mostly Mostly free-livingfree-living carnivorous species carnivorous species

• commensal animals inside invertebrates commensal animals inside invertebrates (oysters, crabs, etc.)(oysters, crabs, etc.)

• Most commonly seen (Most commonly seen (Why?Why?))• Label ocelli=eyespotsLabel ocelli=eyespots

VI. Phylum AnnelidaVI. Phylum Annelida

• SegmentedSegmented worms (1mm-3m) – flex/move worms (1mm-3m) – flex/move more easilymore easily

• Internally and externally, internal Internally and externally, internal structures in tandemstructures in tandem

• Protective elastic cuticleProtective elastic cuticle• Body composed of repeated segmentsBody composed of repeated segments

• Gut runs through all segments in body Gut runs through all segments in body cavity (cavity (coelom-space around gutcoelom-space around gut))

• Coelom filled with fluid – Coelom filled with fluid – hydrostatic hydrostatic skeletonskeleton

• Coelom divided with Coelom divided with septasepta-correspond to -correspond to segmentssegments

Leech

Sabella pavonina

Nereis sp.

Lumbicus terrestris

VI. Phylum AnnelidaVI. Phylum Annelida

A.A. Class Polychaeta – tube worms, feather Class Polychaeta – tube worms, feather dustersdusters

• Body segments have pairs of Body segments have pairs of parapodiaparapodia• Parapodia for locomotion, feeding, gas Parapodia for locomotion, feeding, gas

exchange, protection exchange, protection • tipped with tipped with setaesetae (bristles), often 4 pairs (bristles), often 4 pairs• Respiration: some with gills, exchange Respiration: some with gills, exchange

through bodythrough body

VI. Phylum AnnelidaVI. Phylum Annelida

A.A. Class PolychaetaClass Polychaeta• Larva = Larva = TrochophoreTrochophore

• Band of cilia around bodyBand of cilia around body

• Diverse lifestylesDiverse lifestyles• Free-living predatorsFree-living predators• BurrowingBurrowing• Tube buildingTube building

Fig. 7.14

VI. Phylum AnnelidaVI. Phylum Annelida

B.B. Class Oligochaeta - earthwormsClass Oligochaeta - earthworms• Few marine speciesFew marine species• Benthic – mud and sand (deposit feeders)Benthic – mud and sand (deposit feeders)• No parapodiaNo parapodia• Locomotion – expansion and contractionLocomotion – expansion and contraction

C.C. Class Hirudinea (Leeches)Class Hirudinea (Leeches)• Freshwater mostlyFreshwater mostly• No parapodiaNo parapodia• One anterior/one posterior sucker to attachOne anterior/one posterior sucker to attach• HirudinHirudin – anticoagulating chemical so blood does – anticoagulating chemical so blood does

not clotnot clot

© 2004 Amanda Demopoulos