phylum porifera sponges ancient group of animals that dates back to the late precambrian about 600...
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Phylum Porifera
SpongesAncient group of animals that dates
back to the late Precambrian about 600 million years ago
Phylum Porifera (sponges)
• Sessile, aquatic, benthic, suspension feeders on bacteria and protists
• Mainly marine (~7000 species), but some in freshwater (~300 species).
• ~27 freshwater species in North America.
Phylum Porifera
• Filter feeders (a few are carnivorous)– Water current produced by choanoflagellates delivers
particles and dissolved organic material to all the cells
– Food enters cells by• Phagocytosis (particles)
• Pinocytosis (dissolved organic materials)
– Digestion is intracellular
• Wastes are eliminated by diffusion
• Gas exchange is by diffusion
Defining Characteristic of Phylum
• Cellular level of organization– No true tissues– Cells are not connected to each other by basement
membrane as seen in true tissues
• Cells are totipotent– Can change form and function
• No true embryological germ layers– 3 types of embryological germ layers in animals
• Ectoderm• Endoderm• Mesoderm
Not all animal phyla have all 3 layers
Defining Characteristic of Phylum
• Body covered in holes (ostia)– Pores - hence the name Porifera
• “Pore bearer”– Skeleton made of spicules
• Silica
• CaCO3
• Spongin – organic material
• No fixed body shape• No plane of symmetry
– Some have radial symmetry
Defining Characteristic of Phylum
• Adults are sessile (immobile)
• Suspension feeders
• Flagellated cells called choanocytes circulate water through canal system
• No nerves or muscles
• Larvae are flagellated and free swimming
Defining Characteristic of Phylum
• Microvillae form collars around flagella of Collar cells = Choanocytes
• Functions of choanocytes– Generate currents that
maintain water flow throughout sponge.
– Capture small food particles.– Capture sperm for
fertilization.
nucleus
microvillus
Flagellum
Collar
Sponge Cells • Pinacocytes – form the pinacoderm, the outermost layer of
sponge
• Choanocytes – flagellated collar cells that pump water through the sponge, form the choanoderm
• Amoebocytes (or Archaeocytes) are amoeba-like cells that are totipotent, in other words each is capable of transformation into any other type of cell. They also have important roles in feeding, reproduction and in clearing debris that blocks the ostia. Amoebocytes wander through the central jelly or mesohyle
• Porocytes – line the pores (or ostia) of the sponge; provide channels to spongocoel
Pinacocytes (“tablet cells”) form outer epithelium
Choanocytes circulate water, capture prey, capture sperm
Amoebocytes or archaeocytes Wander through mesohyl;can become other cell types, form gametes, help in feeding, clear debris from ostia
Amoebocytes
Porocytes (pore cells)provide channels to spongocoel
Mesohyl
• Middle layer of sponge
• Acellular matrix– Gelatinous
– Nonliving
– Acellular
• Contains archaeocytes
• Contains spicules and spongin
Osculum
spongocoel(atrium)
Generalized Sponge Anatomy
inhalant pore (ostium)
Pinacoderm made of pinacocytes
Ostia lined by porocytes
Mesohyle with amoebocytes
Choanoderm with choanocytes
Cell Layers
Other types of cells within the mesohyl
• Sclerocytes secrete the mineralized spicules ("little spines") that form the skeletons of many sponges and in some species provide some defense against predators.
• Spongocytes secrete spongin.
• Lophocytes are amoeba-like cells that move slowly through the mesohyl and secrete collagen fibres.
• Collenocytes are another type of collagen-producing cell.
• Rhabdiferous cells secrete polysaccharides that also form part of the mesohyl.
Other types of cells within the mesohyl
• In addition to or instead of sclerocytes, demosponges have spongocytes that secrete a form of collagen that polymerizes into spongin, a thick fibrous material that stiffens the mesohyl.
• No specialized communication cells. Cells signal each other by
DIFFUSION of chemical messages • Myocytes ("muscle cells") regulate the opening and closing of
the porocytes . • "Grey cells" act as the equivalent of an immune system for the
sponge.
• Oocytes and spermatocytes are reproductive cells.
Sponge Skeletal MaterialsSponge Skeletal Materials
• SpiculesSpicules and and sponginspongin fibers are fibers are– StructuralStructural– Used in defense against predatorsUsed in defense against predators
• Also important for identification of spongesAlso important for identification of sponges
Sclerocytes - derived from amoebocytes; produce spicules
Growth of a sponge spiculeGrowth of a sponge spicule Growth of a sponge spiculeGrowth of a sponge spicule
Spicule
Founder cell
Thickener cell
Sclerocytes - derived from amoebocytes; produce spicules
Additional spicule shapes
Massive calcium carbonate supports evolved several times independently in the Demospongiae and the Calcarea.
Sponge Body Plans
• Asconoid
• Syconoid
• Leuconoid
• See handout for details of water flow and anatomy– for practice, label the following diagrams
Choanocytes Mesohyl Water flow
Asconoid Syconoid Leuconoid
Pinacocytes
Leucosolenia
Asconoid sponge
Leucosolenia
Asconoid Body Plan
Simplest body type
Found only in the Calcarea
Choanoderm is simple and continuous
Water:
• enters through pores
• and flows into spongocoel
• then out through osculum.
Spicule
Pinacoderm
Porocyte
Osculum
Spongocoel
Mesohyl
Amoebocyte
Choanocyte in choanoderm
Inhalant pore
Structure and organization of Structure and organization of an an asconoidasconoid sponge. sponge.
Structure and organization of Structure and organization of an an asconoidasconoid sponge. sponge.
Grantia = Scypha = Sycon
See following slides for anatomy
Grantia = Scypha = Sycon
Syconoid Body PlanMore complex body type
Choanoderm is folded into many radial canals
Water:• enters through pores• and travels through radial
canals to spongocoel• then out through osculum.
Structure and organization of Structure and organization of a a syconoidsyconoid sponge. sponge.
Structure and organization of Structure and organization of a a syconoidsyconoid sponge. sponge.
Spongocoel
Pinacoderm
Choanocyte
Mesohyl
Amoebocyte
Osculum
Spicule
Radial Canal
Incurrent Pore
Incurrent Canal
Internal water canal
Grantia longitudinal section; water flow shown by arrows
apopyle
Grantia cross section; water flow shown by arrows.
Grantia
details of radial canal
Structure and organization of a Structure and organization of a leuconoidleuconoid sponge sponge
Leuconoid Body PlanMost common and most complex type of sponge body
Water:• flows in through pores into
inhalant canals. • It then enters choanocyte
lined chambers… • …and finally travels the
excurrent canals to the osculum.
Detailed organization of the leuconoid sponge
Prosopyle
Apopyle
HexactinellidaHexactinellida
Glass sponge community in Antarctica's Glass sponge community in Antarctica's eastern Weddell Sea, in an area not eastern Weddell Sea, in an area not
covered by ice shelves covered by ice shelves
• Major component of the body is the trabecular syncytium.• Flagellated cells lack nuclei, and are called collar bodies. • Produced by nucleated choanoblasts.
Trabecular Syncytium
• Is the largest example of a syncytium known in the animal kingdom.
• Comes from fusion of early embryonic cells.• Embryos are cellular until gastrulation
• SO - Hexactinellid sponges may have evolved from cellular sponges
• Syncytium– Is Cytoplasmic– Lacks cell walls– Possesses multiple nuclei– Is bilayered – Extends through the
entire body of the sponge.
• Syncytium– Connects through
cytoplasmic bridges to various cells in the sponge, such as choanocytes and archaeocytes.
Trabecular Syncytium
• Primary reticulum, encloses and supports the collar bodies and the choanoblasts
• Secondary reticulum, branches from the primary reticulum and forms a kind of barrier around the collars of the collar bodies.
• Nuclei are scattered within the two reticula. • Water is drawn through openings, or prosopyles, and
moves through the microvilli of the collar bodies then through the excurrent canals to the outside through apopyles.
• Some water passes directly through the prosopyles into the flagellated chamber
prosopopyle
blast
Trabecular Syncytium
• Cytoplasm within the syncytium flows bidirectionally.
• Food products may be distributed through the sponge via the syncytium and not via cellular transport as in other sponges.
Classification
• 2 subphyla– Symplasma– Cellularia
• 4 Classes based on type of spicules– Hexactinellida– Calcarea– Demospongiae– Homoscleromorpha
Classification
• Based on type of skeleton– Class Hexactinellida
• Spicules made of silica (glass)• Maybe should be separate phylum
– Class Calcarea• Spicules made of calcium carbonate
– Class Demospongiae• Siliceous spicules in some• Spongin fibers only in some• Both spicules and spongin fibers• One family lacks a skeleton entirely
Classification
• Subphylum: Symplasma– Class: Hexactinellida
• Acellular syncitium– Trabecular syncitium (discussed later)
• Spicules made of silica (glass sponges)
Hexactinellida
= Hexactinellida
Hexactinellida
• Live in deep water
• Habitat favored possibly because body structures are so fragile.
Euplectella Euplectella Venus’ Flower Venus’ Flower Basket SpongeBasket Sponge
A deep water species. Often A deep water species. Often contains a pair of shrimp that contains a pair of shrimp that entered as juveniles and remain entered as juveniles and remain trapped inside their entire lives. trapped inside their entire lives. Usually many small shrimp Usually many small shrimp arrive and the first pair to arrive and the first pair to achieve sexual maturity kill off achieve sexual maturity kill off the rest. Often given to the rest. Often given to Japanese couples as a wedding Japanese couples as a wedding present symbolizing fidelity and present symbolizing fidelity and long life together.long life together.
Hmmmmmm – prisoners and Hmmmmmm – prisoners and murderers?murderers?
SpongicoloidesSpongicoloides
Spongicoloides
• Unusual eyes. – In contrast to the sensitive optics used in the eyes
of almost all other adult decapod shrimps, spongicolids retain the less sensitive optics used by larval decapods. (We’ll talk about this later with discussion of arthropods.)
– These eyes are derived by neoteny, possibly reflecting the limited value of more specialised eyes within the body cavity of the sponge at depths of 100 – 1500 m.
SpongillaSpongilla
Freshwater Freshwater SpongeSponge
HexactinellidaeHexactinellidae
Freshwater sponges are useful for Freshwater sponges are useful for monitoring pollution. In addition, they monitoring pollution. In addition, they produce an antibiotic that may have produce an antibiotic that may have important biomedical and ecological important biomedical and ecological functions.functions.
Read article on East Chicago Sanitary Read article on East Chicago Sanitary District Wastewater Treatment Plant – District Wastewater Treatment Plant – sponges and salmonsponges and salmon
http://www.chicagowildernessmag.org/issues/fall2007/sponges.html
Watch the video!Watch the video!
HexactinellidaSpicules: 6-sided
Siliceous spicules
Electron micrograph
Yellow Picasso sponges (Staurocalyptus sp.)
Siliceous spicules
Ernst Haeckel
Siliceous Spicules
Classification
• Subphylum: Cellularia– Class: Calcarea
• Spicules made of calcium carbonate
SP Cellularia(Class Calcarea)Clathrina canariensis
SP Cellularia(Class Calcarea)
Classification
• Subphylum: Cellularia– Class Demospongiae
• Siliceous spicules• Spongin fibers only• Both spicules and spongin fibers• One family lacks a skeleton entirely
Spongin fibers
SP Cellularia SP Cellularia (Class (Class Homoscleromorpha)Homoscleromorpha)
Classification
• Subphylum: Cellularia– Class: Homoscleromorpha (newly separated
from Demospongiae)• Very simple structure- once considered to be
“primitive” sponges
Homoscleromorpha
– Reduced skeletons; some lack spicules entirely
– Spicules are all the same (homoschleromorpha)
– Spicules are siliceous
– Spicules tend to be very small, don’t form a well-organized skeleton.
Classification
• Subphylum: Cellularia– Class: Homoscleromorpha (newly
separated from Demospongiae)
• Small group (<100 described species in 2 families) of exclusively marine sponges
• Generally located in shallow waters from 8 to 60 m, but also at more than 1000 m depth
• Dwellers of hard substrate communities often in semi-dark or dark caves
Homoscleromorpha
• Reproduction is viviparous
• Larva = amphiblastula.
• Suspension feeders
• Chemical defense producers
• Builders of substrate
• Bioeroders of calcareous concretions
Homoscleromorpha
• Characters shared with Eumetazoa– True epithelium: basement membrane
with collagen – zonula adhaerens cell junctions– Acrosomes in sperm
• Character shared with calcareous sponges– Cross-striated rootlets in the flagellar
basal apparatus of larval cells– (Also found in at least one
demosponge)
(f) Oscarella viridis TEM micrograph showing basement membrane (arrow heads)
(h) Plakina trilopha TEM micrograph of the cross-striated ciliary rootlet
(i) Oscarella microlobata TEM micrograph of cell junctions (zonula adhaerens)
