biology 320 invertebrate zoology fall 2005 chapter 5 – phylum porifera
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Biology 320Biology 320Invertebrate ZoologyInvertebrate Zoology
Fall 2005Fall 2005
Chapter 5 – Phylum PoriferaChapter 5 – Phylum Porifera
Phylum PoriferaPhylum Porifera The spongesThe sponges
Name Porifera means “pore Name Porifera means “pore bearers”bearers”
First metazoan phylum we will First metazoan phylum we will discussdiscuss
Posses epithelioid and rudimentary Posses epithelioid and rudimentary connective tissueconnective tissue
Lack true muscle and nervous Lack true muscle and nervous tissuestissues
Not considered to be eumetazoansNot considered to be eumetazoans
Approximately 8000 spp. Approximately 8000 spp. of spongesof sponges
Mostly marine, with Mostly marine, with approx. 150 described approx. 150 described freshwater spp.freshwater spp.
Primitive, sessile filter Primitive, sessile filter feedersfeeders
Most are asymmetrical, Most are asymmetrical, but some display radial but some display radial symmetrysymmetry
Can be erect, branching, Can be erect, branching, or encrusting on or encrusting on substratumsubstratum
Body DesignBody Design
Three main forms of sponges, classified according Three main forms of sponges, classified according to complexityto complexity
AsconoidAsconoid SyconoidSyconoid LeuconoidLeuconoid
Asconoid spongesAsconoid sponges Simplest body planSimplest body plan Resemble a hollow tube, with the base attached to the substrateResemble a hollow tube, with the base attached to the substrate Possesses one large spongocoel lined with a single layer of Possesses one large spongocoel lined with a single layer of
choanodermchoanoderm Choanocytes beat and draw water through ostia in the epidermisChoanocytes beat and draw water through ostia in the epidermis
Asconoid sponges cont…Asconoid sponges cont… Water exits spongocoel through a Water exits spongocoel through a
single large osculumsingle large osculum
Smallest of all sponges (1mm in Smallest of all sponges (1mm in diameter)diameter)
Thinnest body wallsThinnest body walls
LeucosoleniaLeucosolenia
Growth is limited by spongocoel Growth is limited by spongocoel diameterdiameter
If asconoid sponges had larger If asconoid sponges had larger diameters, body volume would diameters, body volume would exceed pumping capacity of exceed pumping capacity of choanodermchoanoderm
Therefore, a only a change in this Therefore, a only a change in this simple body plan would permit the simple body plan would permit the evolution of larger body sizes in evolution of larger body sizes in spongessponges
Syconoid SpongesSyconoid Sponges Body wall contains pockets, Body wall contains pockets,
known as choanocyte chambers, known as choanocyte chambers, that are lined with choanodermthat are lined with choanoderm
Increases choanoderm surface Increases choanoderm surface areaarea
Decreases spongocoel volumeDecreases spongocoel volume
Larger than asconoid sponges Larger than asconoid sponges (one cm – a few cm)(one cm – a few cm)
Body walls are thicker than in Body walls are thicker than in asconoid spongesasconoid sponges
GrantiaGrantia and and SyconSycon (formerly (formerly ScyphaScypha))
Leuconoid spongesLeuconoid sponges
Contains thousands of Contains thousands of choanocyte chambers, choanocyte chambers, thereby further increasing thereby further increasing the choanoderm SAthe choanoderm SA
Spongocoel is further Spongocoel is further reducedreduced
Therefore, these are the Therefore, these are the largest sponges (few cm to largest sponges (few cm to one meter, or more)one meter, or more)
Thickest body wallsThickest body walls
May possess more than one May possess more than one osculumosculum
Body Wall CompositionBody Wall Composition The body walls of sponges are classified as either The body walls of sponges are classified as either
being cellular or syncytialbeing cellular or syncytial
Cellular sponges have two primitive Cellular sponges have two primitive primaryprimary tissuestissues Epithelioid – resembles epitheliumEpithelioid – resembles epithelium Mesohyl – connective tissue middle layerMesohyl – connective tissue middle layer
There are two There are two specificspecific types of epithelioid tissue types of epithelioid tissue Pinacoderm – lines inside (except where choanoderm is Pinacoderm – lines inside (except where choanoderm is
present) and outsidepresent) and outside Choanoderm – choanocytes posses a flagellum and Choanoderm – choanocytes posses a flagellum and
collar of microvillicollar of microvilli
Mesohyl is a fibrous (proteinaceous) ECM Mesohyl is a fibrous (proteinaceous) ECM containing cells and skeletal elementscontaining cells and skeletal elements
All mesohyl cells are totipotent and amoeboidAll mesohyl cells are totipotent and amoeboid Archeocytes – can differentiate into any type of Archeocytes – can differentiate into any type of
sponge cell. Aide in digestion (via phagocytosis) sponge cell. Aide in digestion (via phagocytosis) and internal transportand internal transport
Lophocytes – secrete and maintain collagen Lophocytes – secrete and maintain collagen fibersfibers
Spongocytes – responsible for producing thick Spongocytes – responsible for producing thick skeletal fibers known as sponginskeletal fibers known as spongin
Mesohyl cells cont…Mesohyl cells cont…
Sclerocytes – secrete Sclerocytes – secrete spicules, interesting spicules, interesting skeletal elements made of skeletal elements made of silica or calciumsilica or calcium
Myocytes – essentially Myocytes – essentially muscle cells; usually muscle cells; usually concentrated around concentrated around osculum. Constrict or osculum. Constrict or dilate to control water flowdilate to control water flow
Germ cells – reproductive Germ cells – reproductive cellscells
Syncytial sponges DO posses cells, but not at Syncytial sponges DO posses cells, but not at the same level of organization as cellular the same level of organization as cellular spongessponges
Cytoplasm is continuous and lacks membranes that Cytoplasm is continuous and lacks membranes that compartmentalize separate cellscompartmentalize separate cells
Lack pinacodermLack pinacoderm
Lack choanoderm. Posses collar bodies instead; Lack choanoderm. Posses collar bodies instead; these are located in collar body chambers, individually these are located in collar body chambers, individually rather than in epitheliod sheetsrather than in epitheliod sheets
Mesohyl is present and contains archeocytes, Mesohyl is present and contains archeocytes, sclerocytes, and germ cellssclerocytes, and germ cells
Syncytial sponges cont…Syncytial sponges cont… Body wall resembles a 3D cobweb-like pattern and is called a Body wall resembles a 3D cobweb-like pattern and is called a
trabecular syncytiumtrabecular syncytium
Each strand of the trabecular syncytium encloses an axis of Each strand of the trabecular syncytium encloses an axis of mesohylmesohyl
Collagen and spicules are presentCollagen and spicules are present
TaxonomyTaxonomy Two subphylaTwo subphyla
Subphylum Symplasma Subphylum Symplasma (Hexactinellida)(Hexactinellida)
Subphylum CellulariaSubphylum Cellularia
Subphylum Symplasma Subphylum Symplasma consists of glass sponges consists of glass sponges that posses syncytial tissuesthat posses syncytial tissues
Most sponges belong to Most sponges belong to Subphylum Cellularia, which Subphylum Cellularia, which is divided into two main is divided into two main classes, both possessing classes, both possessing cellular tissuescellular tissues
Class Demospongiae – have Class Demospongiae – have siliceous spicules and sponginsiliceous spicules and spongin
Class Calcarea – have Class Calcarea – have calcareous spiculescalcareous spicules
SkeletonSkeleton Any cell, organism, etc. needs Any cell, organism, etc. needs
some form of supportsome form of support
Mesohyl acts as an Mesohyl acts as an endoskeletonendoskeleton
Diversity of mesohylar structureDiversity of mesohylar structure Fine collagen fibers onlyFine collagen fibers only
May be supplemented with spicules, May be supplemented with spicules, spongin, or bothspongin, or both
Incredible diversity of spicules; and Incredible diversity of spicules; and some can project through mesohyl some can project through mesohyl to protect the outside of the spongeto protect the outside of the sponge
Water PumpingWater Pumping
Most pump a volume of Most pump a volume of water equal to their body water equal to their body volume, every 5 secondsvolume, every 5 seconds
Can slow / stop water flow Can slow / stop water flow to avoid taking in siltto avoid taking in silt
Can control rate of water Can control rate of water flow viaflow via
Contracting or relaxing Contracting or relaxing myocytes, which controls myocytes, which controls osculum diameterosculum diameter
Closing ostiaClosing ostia
Adjusting flagellar beat of Adjusting flagellar beat of choanoderm / collar bodieschoanoderm / collar bodies
LocomotionLocomotion
Some have limited Some have limited capacity for locomotioncapacity for locomotion
Can move 1 to 4 mm per Can move 1 to 4 mm per dayday
Result of collected Result of collected amoeboid movement of amoeboid movement of cellscells
Osculum contractionOsculum contraction
Whole body contractionWhole body contraction
NutritionNutrition Filter feedersFilter feeders
Typically phagocytize Typically phagocytize particles of 50µm or lessparticles of 50µm or less
Particle size determines Particle size determines which cells phagocytizewhich cells phagocytize
All cells can phagocytizeAll cells can phagocytize
Choanocytes transfer Choanocytes transfer particles to vacuoles for particles to vacuoles for digestiondigestion
Archeocytes remove Archeocytes remove wastes / inorganics from wastes / inorganics from systemsystem
Feed on dinoflagellates, bacteria, viruses, debris, etc.Feed on dinoflagellates, bacteria, viruses, debris, etc.
Some are carnivorous (don’t filter); trap small animals such Some are carnivorous (don’t filter); trap small animals such as crustaceansas crustaceans
May posses photosynthetic May posses photosynthetic endosymbiontsendosymbionts
CyanobacteriaCyanobacteria DinoflagellatesDinoflagellates ChlorophytesChlorophytes
Symbionts may cause Symbionts may cause sponge to be brightly sponge to be brightly coloredcolored
Sponges must live in Sponges must live in shallow water to shallow water to photosynthesizephotosynthesize
Some obtain up to 80% of Some obtain up to 80% of nutrients from nutrients from photosynthatephotosynthate
Internal TransportInternal Transport Gas / waste transport is carried out via simple diffusionGas / waste transport is carried out via simple diffusion
Sponges are “leaky,” so water penetrates almost the entire Sponges are “leaky,” so water penetrates almost the entire animalanimal
Sheets of cells are only one cell layer thickSheets of cells are only one cell layer thick Mobile amoeboid cellsMobile amoeboid cells
Ammonia is the main metabolic wasteAmmonia is the main metabolic waste Almost always the case for animals in aqueous environmentsAlmost always the case for animals in aqueous environments Uric acid or urea in terrestrial habitatsUric acid or urea in terrestrial habitats
Archeocytes transfer wastes / nutrientsArcheocytes transfer wastes / nutrients
Some individual cells posses contractile vacuolesSome individual cells posses contractile vacuoles
Nervous TissueNervous Tissue
Lack nerve cellsLack nerve cells
Some have localized Some have localized impulses responsible for impulses responsible for myocyte contractionmyocyte contraction
Glass sponges can generate Glass sponges can generate action potentials that travel action potentials that travel all across their syncytium at all across their syncytium at a rapid ratea rapid rate
Used to arrest flagellar beatingUsed to arrest flagellar beating
EcologyEcology Many produce toxins to Many produce toxins to
prevent predationprevent predation
Some animals are Some animals are spongivoresspongivores
Nudibranchs Nudibranchs FishFish Turtles – Hawksbill turtle feces Turtles – Hawksbill turtle feces
can be up to 95% siliceous can be up to 95% siliceous spiculesspicules
Some release chemicals Some release chemicals that kill competing sessile that kill competing sessile organisms, such as corals organisms, such as corals
Some animals such as Some animals such as shrimps and brittle stars shrimps and brittle stars live in spongeslive in sponges
Decorator crabs may Decorator crabs may place sponges on their place sponges on their carapacescarapaces
ClionaCliona breaks down breaks down calcareous shells. Bores calcareous shells. Bores into shells for protectioninto shells for protection
ReproductionReproduction Sponges are excellent regeneratorsSponges are excellent regenerators
Reproduce clonally through several methodsReproduce clonally through several methods Fragmentation – usually due to wave damage or Fragmentation – usually due to wave damage or
grazinggrazing
BuddingBudding
Gemmules (winter bodies) – spore-like structures that Gemmules (winter bodies) – spore-like structures that are essentially a mass of nutrient-laden archeocytes are essentially a mass of nutrient-laden archeocytes that are surrounded by a shell. Undergo diapause that are surrounded by a shell. Undergo diapause
Sponges frequently Sponges frequently reproduce sexuallyreproduce sexually
Sponges are Sponges are hermaphrodites hermaphrodites (monoecious)(monoecious)
Germ cells occur Germ cells occur throughout mesohyl throughout mesohyl Choanocytes can Choanocytes can
also release sperm, also release sperm, and form eggsand form eggs
Sperm are broadcasted Sperm are broadcasted into water columninto water column
Choanocytes phagocytize Choanocytes phagocytize incoming sperm, but don’t incoming sperm, but don’t digestdigest
They differentiate into an They differentiate into an amoeboid cell and deliver amoeboid cell and deliver sperm head to eggsperm head to egg
Most eggs are fertilized Most eggs are fertilized through phagocytosis through phagocytosis (therefore, most sponge (therefore, most sponge sperm lack an acrosome)sperm lack an acrosome)
Some sponges are oviparous, and release zygotes into water columnSome sponges are oviparous, and release zygotes into water column
Most are viviparous, and retain zygotes in their body, later releasing Most are viviparous, and retain zygotes in their body, later releasing larvaelarvae
Sponge larvae are very diverseSponge larvae are very diverse
Larvae are short livedLarvae are short lived Settle within a few daysSettle within a few days
Creep across substrate until a Creep across substrate until a suitable spot is foundsuitable spot is found
Metamorphose into a juvenileMetamorphose into a juvenile
Varied lifespansVaried lifespans May live one to a few years in May live one to a few years in
temperate zonestemperate zones
Tropical or deep sea spp. May live Tropical or deep sea spp. May live 200 years or more200 years or more
Some only grow 0.2 mm/yr, and Some only grow 0.2 mm/yr, and could be 5000 years old if that could be 5000 years old if that growth rate is constantgrowth rate is constant
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