Kingdom Kingdom AnimaliaAnimalia

Phylum Phylum CnidariaCnidaria

CharacteristicsCharacteristics Radial or biradial symmetryRadial or biradial symmetry Diploblastic organizationDiploblastic organization Mesoglea between epidermis Mesoglea between epidermis

and gastrodermisand gastrodermis Gastrovascular cavityGastrovascular cavity Nerve netNerve net Cnidocytes – used in defense Cnidocytes – used in defense

and feedingand feeding

Reproduction/Life Reproduction/Life CycleCycle

Can be monoecious or Can be monoecious or dioeciousdioecious

Alternate generations Alternate generations between polyp and medusa between polyp and medusa formform

Polyp – asexual and sessilePolyp – asexual and sessile Medusa – dioecious and Medusa – dioecious and

free swimmingfree swimming

Reproduction Reproduction Cont’dCont’d

Planula – Cnidaria larvaePlanula – Cnidaria larvae Polyps are produced by Polyps are produced by

budding or planulabudding or planula Medusae formed by Medusae formed by

budding from a polyp body budding from a polyp body wallwall

FeedingFeeding Use cnidocytes to stun or Use cnidocytes to stun or

kill preykill prey Tentacles contract to Tentacles contract to

bring food to mouthbring food to mouth Food is digested in Food is digested in

gastrovascular cavitygastrovascular cavity

Support and Support and LocomotionLocomotion

Hydrostatic SkeletonHydrostatic Skeleton Some classes have Some classes have

longitudinal muscles that longitudinal muscles that aid in movementaid in movement

Polyps – somersault, Polyps – somersault, inchworm, glide on base, inchworm, glide on base, and walk on their tentaclesand walk on their tentacles

Medusae – swim and floatMedusae – swim and float

ClassificationClassification Class HydrozoaClass HydrozoaClass ScyphozoaClass ScyphozoaClass CubozoaClass CubozoaClass AnthozoaClass Anthozoa

Class HydrozoaClass Hydrozoa Mostly marine, but the only Mostly marine, but the only

class with freshwater class with freshwater members!members!

Alternate generationsAlternate generations Mostly colonial polypsMostly colonial polyps

ObeliaObelia Gastrozooid – feeding polyp Gastrozooid – feeding polyp

formed from planula larvaeformed from planula larvae Grows through budding into Grows through budding into

more gastrozooidsmore gastrozooids Gonozooid – reproductive Gonozooid – reproductive

polyp that forms medusa by polyp that forms medusa by buddingbudding

Medusae then reproduce Medusae then reproduce sexuallysexually

Gonozooid

Gastrozooid

GonionemusGonionemus Medusa predominantMedusa predominant Has a velum (shelf-like lip Has a velum (shelf-like lip

that projects inward)that projects inward) Velum creates jet propulsionVelum creates jet propulsion Mouth at end of a manubriumMouth at end of a manubrium Nerve ring that coordinates Nerve ring that coordinates

swimming movementsswimming movements Statocyst – responds to gravityStatocyst – responds to gravity

HydraHydra FreshwaterFreshwater Polyps only, Polyps only,

no medusaeno medusae Testes form Testes form

sperm by sperm by meiosismeiosis

Ovaries Ovaries form one form one egg eachegg each

PhysaliaPhysalia Portuguese Portuguese

man-of-warman-of-war ColonialColonial Cannot swimCannot swim Cnidocytes in Cnidocytes in

tentacles are tentacles are lethal to small lethal to small vertebrates and vertebrates and dangerous to dangerous to humanshumans

Class ScyphozoaClass Scyphozoa All marineAll marine ““True Jellyfish” – medusa True Jellyfish” – medusa

dominantdominant

Stinging Nettle, Stinging Nettle, MastigiasMastigias

AureliaAurelia Gastrodermal cells have Gastrodermal cells have

cilia to circulate foodcilia to circulate food Feeds on planktonFeeds on plankton Rhopalia – chemoreceptorsRhopalia – chemoreceptors Lappets – touch receptorsLappets – touch receptors Statocysts – gravity Statocysts – gravity

sensorssensors Ocelli - photoreceptorsOcelli - photoreceptors

Class CubozoaClass Cubozoa Medusae Medusae

are cuboidalare cuboidal Polyps are Polyps are

reduced or reduced or absentabsent

Tentacles Tentacles hang from hang from cornerscorners

Class AnthozoaClass Anthozoa Polyps only, no medusaePolyps only, no medusae Mouth has a pharynxMouth has a pharynx Gastrovascular cavity is Gastrovascular cavity is

divided into sectionsdivided into sections Sexual and asexual Sexual and asexual

reproductionreproduction

Sea AnemonesSea Anemones

CoralsCorals