phyla porifera, cnidaria, and ctenophora

Phyla Porifera, Cnidaria, Phyla Porifera, Cnidaria, and Ctenophoraand Ctenophora

Chapter 9Chapter 9

Phylum Porifera (Sponges)Phylum Porifera (Sponges)

• Poriferans are mostly marine Poriferans are mostly marine animals.animals.

• Characteristics include:Characteristics include:– Asymmetrical or radial symmetryAsymmetrical or radial symmetry– Three types of cellsThree types of cells– Central cavity for water circulationCentral cavity for water circulation– No tissue or organsNo tissue or organs– Mostly sessileMostly sessile

Poriferan Cell TypesPoriferan Cell Types

• PinacocytesPinacocytes– Thin, flat cells that line the outer surface of spongesThin, flat cells that line the outer surface of sponges– Some specialized into porocytes that regulate water Some specialized into porocytes that regulate water

circulationcirculation• Amoeboid cellsAmoeboid cells

– Contained in jellylike mesohyl layerContained in jellylike mesohyl layer– Function in reproduction, secreting skeletal elements, Function in reproduction, secreting skeletal elements,

transporting and storing food, and forming contractile transporting and storing food, and forming contractile rings around openings in the wallrings around openings in the wall

• ChoanocytesChoanocytes– Collar cells lining inner chamberCollar cells lining inner chamber– Flagellated with microvilli surrounding each flagellumFlagellated with microvilli surrounding each flagellum– Flagella create water current and the collar of microvilli Flagella create water current and the collar of microvilli

filters food particlesfilters food particles

http://www.waycross.edu/faculty/gcook/ecology/animalia/zoa.html

Sponge SkeletonSponge Skeleton

• Sponge skeletons may be made of Sponge skeletons may be made of needlelike spikes called spicules.needlelike spikes called spicules.– Spicules are made of calcium carbonate or Spicules are made of calcium carbonate or

silica and are formed by amoeboid cells.silica and are formed by amoeboid cells.

• Some sponges have skeletons made of Some sponges have skeletons made of spongin which is made of collagenspongin which is made of collagen– Spongin skeletons are used as commercial Spongin skeletons are used as commercial

spongessponges

http://www-biol.paisley.ac.uk/biomedia/graphics/jpegs/SPICULES.gif

Ascon Body FormAscon Body Form

• Vaselike shapeVaselike shape• Outer openings of porocytes are Outer openings of porocytes are

called ostia (singular-ostium)called ostia (singular-ostium)– Ostia lead directly to inner chamber Ostia lead directly to inner chamber

called the spongocoel which is lined with called the spongocoel which is lined with choanocyteschoanocytes

• Water is drawn in through ostia and Water is drawn in through ostia and exits throughexits through large opening at the large opening at the top of the sponge called the osculum.top of the sponge called the osculum.

http://mac01.eps.pitt.edu/geoweb/courses/GEO1200/lab3/structure.htm

Sycon Body FormSycon Body Form

• Outer wall appears foldedOuter wall appears folded• Water enters through openings called Water enters through openings called

dermal pores which are openings of dermal pores which are openings of incurrent canals (infolded invaginations).incurrent canals (infolded invaginations).

• Incurrent canals are connected to radial Incurrent canals are connected to radial canals through pores.canals through pores.

• Radial canals are lined with choanocytes Radial canals are lined with choanocytes and lead to the spongocoel.and lead to the spongocoel.

• Spongocoel has an osculum.Spongocoel has an osculum.

Leucon Body FormLeucon Body Form

• Leucon body forms contain an extensively Leucon body forms contain an extensively branched canal system.branched canal system.

• Water enters through ostia and enters Water enters through ostia and enters incurrent canals.incurrent canals.

• Incurrent canals lead to choanocyte Incurrent canals lead to choanocyte chambers and leaves chambers through chambers and leaves chambers through excurrent canals.excurrent canals.

• No spongocoel is present and there are No spongocoel is present and there are multiple oscula.multiple oscula.

Nutrition and Gas ExchangeNutrition and Gas Exchange

• Sponges feed on bacteria, microscopic algae, protists, and Sponges feed on bacteria, microscopic algae, protists, and other microscopic organisms.other microscopic organisms.

• Some deep water sponges (Genus Some deep water sponges (Genus AsbestoplumaAsbestopluma) are ) are carnivorous and feed on small crustaceans.carnivorous and feed on small crustaceans.

• Sponges serve the ecosystem by filtering water and Sponges serve the ecosystem by filtering water and reducing turbity (cloudiness).reducing turbity (cloudiness).– A 1 cm by 10 cm sponge can filter 20 liters of water every day.A 1 cm by 10 cm sponge can filter 20 liters of water every day.

• Food is filtered and trapped by choanocyte cells and then Food is filtered and trapped by choanocyte cells and then trapped by food vacuoles where digestion by enzymes trapped by food vacuoles where digestion by enzymes begins. begins. – Amoeboid cells distribute digested food products to other cells.Amoeboid cells distribute digested food products to other cells.

• Nutrients can also be phagocytized by pinacocytes along Nutrients can also be phagocytized by pinacocytes along incurrent canals or absorbed by active transport.incurrent canals or absorbed by active transport.

• Gas exchange and excretion of nitrogenous wastes occur Gas exchange and excretion of nitrogenous wastes occur by diffusionby diffusion

http://scilib.ucsd.edu/sio/nsf/fguide/porifera26.html

Asbestopluma

Cellular CommunicationCellular Communication

• Sponges do not have a nervous system for Sponges do not have a nervous system for cell to cell communicationcell to cell communication

• Cells respond to stimuli in the environment Cells respond to stimuli in the environment to regulate activities.to regulate activities.– Example: Sunlight inhibits constriction of ostia Example: Sunlight inhibits constriction of ostia

keeping them open, thus maintaining keeping them open, thus maintaining maximum water circulation during sunlight maximum water circulation during sunlight hours.hours.

• Some cellular communication may be Some cellular communication may be present due to observations of activity present due to observations of activity changes with no external stimulus.changes with no external stimulus.– Method of communication is unknown.Method of communication is unknown.

ReproductionReproduction

• Most sponges are monoecious meaning both sexes occur in Most sponges are monoecious meaning both sexes occur in one organism.one organism.– Egg and sperm are produced at different time to prevent self Egg and sperm are produced at different time to prevent self

fertilization.fertilization.– Egg and sperm are derived from meiotic choanocytes.Egg and sperm are derived from meiotic choanocytes.– Eggs are stored in mesohyl.Eggs are stored in mesohyl.– Sperm exit one sponge through its osculum and enter another Sperm exit one sponge through its osculum and enter another

with incurrent water.with incurrent water.– Sperm are transferred to egg by amoeboid choanocytes.Sperm are transferred to egg by amoeboid choanocytes.

• Asexual reproduction occurs in some marine sponges and Asexual reproduction occurs in some marine sponges and freshwater sponges.freshwater sponges.– Gemmules containing amoeboid cells are released during Gemmules containing amoeboid cells are released during

winter when the parent dies. The gemmules release the winter when the parent dies. The gemmules release the amoeboid cells during the spring which organize into a sponge.amoeboid cells during the spring which organize into a sponge.

http://www.puk.ac.za/lifesc/zol/zol121/spong1.htm

Life Cycle of SpongesLife Cycle of Sponges

• Earliest development occurs in the Earliest development occurs in the mesohyl.mesohyl.

• The zygote cleaves and forms a flagellated The zygote cleaves and forms a flagellated larva.larva.

• Larva break free of the mesohyl and exit Larva break free of the mesohyl and exit the sponge through water currents.the sponge through water currents.

• The larva free swims for 2 days and finally The larva free swims for 2 days and finally settles on a substrate and develops into settles on a substrate and develops into an adult sponge.an adult sponge.

Porifera ClassificationPorifera Classification

• Class CalcareaClass Calcarea– Calcium carbonate spicule skeletonsCalcium carbonate spicule skeletons– All three body forms representedAll three body forms represented– All marineAll marine– Also known as calcareous spongesAlso known as calcareous sponges– Examples:Examples:

•GrantiaGrantia

•LeucosoleniaLeucosolenia

http://www.bscd.uchicago.edu/classes/biosci184/Images/Grantia.html

http://www.dscc.edu/kjones/bio2animal.htm

http://www.olympusmicro.com/micd/galleries/darkfield/grantia.html

http://www.mareco.org/KML/sponges/pages/leucosolenia%20species_jpg.htm http://www.mareco.org/KML/

sponges/pages/leucosolenia%20eleanor_jpg.htm

http://www.biol.rug.nl/onderwaterbiologie/foto10.jpg

Classification (cont.)Classification (cont.)

• Class HexactinellidaClass Hexactinellida– Silica spicule skeletonsSilica spicule skeletons– Spicules often form intricate latticeSpicules often form intricate lattice– Cup or vase shapedCup or vase shaped– Sycon or leucon body formSycon or leucon body form– Found in tropical West Indies and eastern Found in tropical West Indies and eastern

PacificPacific– Also called glass spongesAlso called glass sponges– Example: Example: Euplectella Euplectella

http://evylmyke.ca/musings/Seasponge.htm

http://www.biology.ualberta.ca/courses.hp/zool250/Labs/Lab03/Euplectella.gif

Classification (cont.)Classification (cont.)

• Class demospongiaeClass demospongiae– Colorful spongesColorful sponges– Silica spicule skeletons or spongin skeletonsSilica spicule skeletons or spongin skeletons– Leucon body formsLeucon body forms– Can grow very large (1 m in height and Can grow very large (1 m in height and

diameter)diameter)– ExamplesExamples

• One family of freshwater sponges (Spongillidae)One family of freshwater sponges (Spongillidae)

• ClionaCliona

• SpongillaSpongilla

http://www.dpo.uab.edu/~acnnnghm/BY255L/BY255LImages/BY255LImages-Porifera/Spongilla-01.jpg

http://www.mareco.org/KML/sponges/images/cliona%20celata2_jpg.jpg

http://www.swan.ac.uk/biodiv/gower/Gower%20Rocky%20shore%20cryptic%20habitats.htm

Phylum Cnidaria Phylum Cnidaria (Coelenterata)(Coelenterata)• Mostly marine animals that possess Mostly marine animals that possess

radial or bilateral symmetryradial or bilateral symmetry

• Diploblastic organization with true Diploblastic organization with true tissuestissues

• Gastrovascular cavity presentGastrovascular cavity present

• Nerve net presentNerve net present

• Cnidocyte cells with nematocysts for Cnidocyte cells with nematocysts for defense, feeding, and attachmentdefense, feeding, and attachment

Body Structure of Body Structure of CnidariansCnidarians• Ectoderm gives rise to epidermis (outer Ectoderm gives rise to epidermis (outer

body layer) body layer) • Endoderm gives rise to gastrodermis Endoderm gives rise to gastrodermis

(inner body layer)(inner body layer)• Each tissue layer possesses specialized Each tissue layer possesses specialized

cells that function in protection, feeding, cells that function in protection, feeding, coordination, movement, digestion and coordination, movement, digestion and absorption.absorption.

• Mesoglea is a jellylike layer between the Mesoglea is a jellylike layer between the epidermis and gastrodermis.epidermis and gastrodermis.

http://www.waycross.edu/faculty/gcook/ecology/animalia/cnido.jpg

CnidocytesCnidocytes

• Cnidocytes are specialized cell that Cnidocytes are specialized cell that produce nematocysts.produce nematocysts.– A nematocyst is a fluid filled capsule with A nematocyst is a fluid filled capsule with

an coiled, hollow tubean coiled, hollow tube– Operculum is a lidlike structure that caps Operculum is a lidlike structure that caps

the capsulethe capsule

• Cnidocyte possesses a cnidocil Cnidocyte possesses a cnidocil (modified cilium) that acts as a sensor (modified cilium) that acts as a sensor to open the operculum and discharge to open the operculum and discharge the coiled tube.the coiled tube.

http://www.wm.edu/act2online/projects/fahey03/cnidaria.html

NematocystsNematocysts

• Nematocysts used for feeding and defense Nematocysts used for feeding and defense have spines that penetrate prey.have spines that penetrate prey.– The spines discharge paralyzing toxins.The spines discharge paralyzing toxins.

• Other nematocysts may have unarmed Other nematocysts may have unarmed tubes for grasping or stick secretions for tubes for grasping or stick secretions for anchoring the animal.anchoring the animal.

• 30 types of nematocysts have been 30 types of nematocysts have been observed with single individuals having six observed with single individuals having six or more different types.or more different types.

http://faculty.shc.edu/cchester/BIO205/Labs/Lab%2004/cnidocytes.htm

http://virtual.yosemite.cc.ca.us/randerson/marine%20invertebrates/nematocy.htm

Alternation of GenerationsAlternation of Generations

• The life cycle of most cnidarians includes two The life cycle of most cnidarians includes two body forms.body forms.– Polyp-asexual, sessile stage that is attached to a Polyp-asexual, sessile stage that is attached to a

substrate and has a cylindrical body and a mouth substrate and has a cylindrical body and a mouth surrounded by food gathering tentacles.surrounded by food gathering tentacles.

– Medusa-dioecious, free swimming stage that is Medusa-dioecious, free swimming stage that is shaped like a bowl with tentacles dangling down.shaped like a bowl with tentacles dangling down.• Mouth is located in the center of the body and faces Mouth is located in the center of the body and faces

down.down.• Movement occurs through pulsations of the body.Movement occurs through pulsations of the body.

Medusae contain much more mesoglea than polyps Medusae contain much more mesoglea than polyps making them more jellylike.making them more jellylike.

http://www.wormguy.com/galimg/uw/pages/polyp.htm

http://antedoonsub.bravehost.com/t.borras/pages/medusa.htm

Feeding and digestionFeeding and digestion

• Most cnidarians feed on small crustaceans.Most cnidarians feed on small crustaceans.– Nematocysts capture prey and tentacles are shortened Nematocysts capture prey and tentacles are shortened

to draw food towards the mouth.to draw food towards the mouth.

• Gastrodermis lines the gastrovascular cavity Gastrodermis lines the gastrovascular cavity where digestion occurs.where digestion occurs.– Gastrodermal gland cells secrete mucus and enzymes to Gastrodermal gland cells secrete mucus and enzymes to

reduce the food to a brothreduce the food to a broth– Nutritive-muscular cells phagocytize food and Nutritive-muscular cells phagocytize food and

incorporate into food vacuoles where digestion is incorporate into food vacuoles where digestion is completed.completed.• These cells also cause peristaltic contractions that cause These cells also cause peristaltic contractions that cause

the movement of food through the vascular cavity and the movement of food through the vascular cavity and expelling undigested material through the mouth.expelling undigested material through the mouth.

http://www.waycross.edu/faculty/gcook/ecology/animalia/anemone%20-%20st.%20andrew%27s.gif

http://www.earthguide.ucsd.edu/hughes2001/acct/lzace/jellyfish.htm

SupportSupport

• Water buoyancy provides most Water buoyancy provides most support needed by cnidarians.support needed by cnidarians.

• Cnidarians also possess a hydrostatic Cnidarians also possess a hydrostatic skeleton-fluids are confined in a skeleton-fluids are confined in a cavity against which contractile cells cavity against which contractile cells of the body act for movement.of the body act for movement.– Epithelio-muscular cells aid movementEpithelio-muscular cells aid movement

MovementMovement

• Polyps Polyps – Somersault from base to tentaclesSomersault from base to tentacles– Wormlike movement using tentacles for Wormlike movement using tentacles for

attachmentattachment– Glide on base or walk on tentaclesGlide on base or walk on tentacles

• MedusaeMedusae– Swim and floatSwim and float

• Horizontal movement-floatingHorizontal movement-floating

• Vertical movement-swimming through pulsations of Vertical movement-swimming through pulsations of the bodythe body

Nerve NetNerve Net

• Nerve cells are interconnected forming a Nerve cells are interconnected forming a nerve net below the epidermis near the nerve net below the epidermis near the mesoglea.mesoglea.

• Nerve nets conducts impulses in response to Nerve nets conducts impulses in response to local stimulilocal stimuli– Strength of stimulus determines distance and Strength of stimulus determines distance and

speed of impulsespeed of impulse• Example: Weak stimulus at a tentacle may cause Example: Weak stimulus at a tentacle may cause

tentacle to retract while strong stimulus in same spot tentacle to retract while strong stimulus in same spot may cause entire organism to move.may cause entire organism to move.

• Sensory receptors are distributed Sensory receptors are distributed throughout the body and can perceive touch throughout the body and can perceive touch and chemicals.and chemicals.

Gas ExchangeGas Exchange

• Large surface area of the cnidarian Large surface area of the cnidarian allows all gas exchange and waste allows all gas exchange and waste elimination to occur by diffusion elimination to occur by diffusion through the body surface.through the body surface.

ReproductionReproduction

• Most cnidarians are dioecious.Most cnidarians are dioecious.• Sperm and egg are released either into the gastrovascular Sperm and egg are released either into the gastrovascular

cavity or into the water.cavity or into the water.• After fertilization the zygote develops into a blastula tissue After fertilization the zygote develops into a blastula tissue

separation begins.separation begins.• The blastula elongates into a planula which is a free The blastula elongates into a planula which is a free

swimming larva which attaches to a substrate.swimming larva which attaches to a substrate.• The gastrovascular cavity forms and a young polyp The gastrovascular cavity forms and a young polyp

develops.develops.• Body wall of the polyp buds to form either a medusa form Body wall of the polyp buds to form either a medusa form

or another polyp. or another polyp. – Some buds may stay attached to the polyp to form a colony of Some buds may stay attached to the polyp to form a colony of

polyps.polyps.

Jellyfish Life CycleJellyfish Life Cycle

Classification of CnidariansClassification of Cnidarians

• Cnidarians are classified in one of 4 Cnidarians are classified in one of 4 classesclasses– Hydrozoa (Hydrozoa (Obelia, Gonionemus, Obelia, Gonionemus,

Physalia)Physalia)– Scyphozoa (true jellyfish, Scyphozoa (true jellyfish, Aurelia)Aurelia)– Cubozoa (Cubozoa (Chironex)Chironex)– Anthozoa (corals, anemones)Anthozoa (corals, anemones)

HydrozoaHydrozoa

• Small, mostly marine, some Small, mostly marine, some freshwaterfreshwater

• Alternation of generations presentAlternation of generations present

• Nematocysts only on epidermisNematocysts only on epidermis

• Gametes released to water rather than Gametes released to water rather than gastrovascular cavitygastrovascular cavity

• Mesoglea is acellular (no specialized Mesoglea is acellular (no specialized cells present)cells present)

ObeliaObelia

• Colonial polypColonial polyp– asexualasexual

• Medusa stageMedusa stage– sexualsexual

GonionemusGonionemus

• Medusa stage predominatesMedusa stage predominates

• Lives in shallow marine watersLives in shallow marine waters

• Clings to seaweedClings to seaweed

• Short polyp stageShort polyp stage

• Gametes released into the waterGametes released into the water

HydraHydra

• FreshwaterFreshwater

• Hangs from plantsHangs from plants

• No medusa stageNo medusa stage

• Polyp reproduces Polyp reproduces both sexually and both sexually and asexuallyasexually

PhysaliaPhysalia

• Portuguese man-Portuguese man-of-warof-war

• colonialcolonial

• Cannot swimCannot swim

• Lethal to small Lethal to small vertebrates, vertebrates, dangerous to dangerous to humanshumans

ScyphozoaScyphozoa

• MarineMarine

• ““True Jellyfish” True Jellyfish” because dominate because dominate stage is medusastage is medusa

• Mesoglea contains Mesoglea contains cellscells

• Cnidocytes on Cnidocytes on epidermis and epidermis and gastrodermisgastrodermis

• AureliaAurelia– common in Pacific common in Pacific

and Atlantic waters and Atlantic waters of N. Americaof N. America

• Mastigias Mastigias quinquecirrhaquinquecirrha– Stinging nettle, Stinging nettle,

AtlanticAtlantic

Aurelia & Mastigia Aurelia & Mastigia quinquecirrhaquinquecirrha

CubozoaCubozoa

• CuboidalCuboidal

• Tentacles hang from Tentacles hang from cornerscorners

• Warm tropical Warm tropical waterswaters

• Chironex fleckeriChironex fleckeri– Sea wasp or box jellySea wasp or box jelly– Off Australian coast Off Australian coast

has caused many has caused many human deathshuman deaths

AnthozoaAnthozoa

• Colonial or solitaryColonial or solitary

• No medusa stage, only polypsNo medusa stage, only polyps

• AnemonesAnemones

• CoralsCorals

• All marioneAll marione

AnemonesAnemones

• SolitarySolitary

• Large and colorfulLarge and colorful

• Attached or buried Attached or buried in a substratein a substrate

• Feed on Feed on invertebrates and invertebrates and fishfish

• Sexual and asexual Sexual and asexual reproductionreproduction

CoralsCorals

• ColonialColonial

• Sexual and asexual Sexual and asexual reproductionreproduction

• Stony corals hard Stony corals hard calcium carbonate calcium carbonate exoskeleton forms exoskeleton forms coral reefscoral reefs

• Soft corals-sea Soft corals-sea pens, sea fanspens, sea fans

Phylum CtenophoraPhylum Ctenophora

• Comb jelliesComb jellies• DiploblasticDiploblastic• Nerve netNerve net• Colloblasts (adhesive structures)Colloblasts (adhesive structures)• 8 comb rows used in locomotion8 comb rows used in locomotion

– Class Tentaculata-with tentacles Class Tentaculata-with tentacles ((Pleurobrancia)Pleurobrancia)

– Class Nuda-Without tentacles (Class Nuda-Without tentacles (BeroeBeroe))

PleurobranchiaPleurobranchia

BeroeBeroe