zly 303 phylum porifera. phylum porifera (sponges) 5000 - 90000 spp. mostly marine some freshwater...
TRANSCRIPT
ZLY 303ZLY 303
Phylum Phylum PoriferaPorifera
Phylum Porifera (Sponges)
5000 - 90000 spp.
mostly marine some freshwater
none terrestrial
3 classes, most important
distinctions are skeletal
Most primitive animal group
DistributionThere are approximately 9,000 living
species and above 2200 fossil forms.All are aquatic–most are marine; found at all depths
from intertidal to the abyssal zone, – a few occur in freshwater (~150 spp.)–most range from <1/2 inch to over 6 ft. tall
(loggerhead sponges),– some are round, flat, grow as crusts or vase-
like,– some are radially symmetrical; most are,– Assymetrical, often brightly colored: yellows,
reds, greens, oranges, lavenders
SimplicityThey are closely related to the group of protozoan protists, called the choanoflagellates,
The protozoan protists cells closely resemble the collar cells of sponges,
Approximately, 1/4th of Sponges genes are shared by all other animals,
All sponges are sessile, but multicellular their structure is unlike any other animal group.
Ecology• Growth is entirely dependent on the following:-• shape of the substratum to which they attach,• the direction or speed of water currents,• Space availabilityTherefore environment plays significance in
growth patterns.
Sponge Biological Associations
Excoriations by sponges into shells and Carapace of Bivalves and Brachipods
Abundance of fossil recordsIn 2010, newly discovered fossils were found
in old rocks that were 635-659 million years old.
About 400 million years ago, sponges dominated the oceans as reef builders,
Some fossil sponge reefs are much larger than the great barrier reef,
Sponges covered an arc across most of Northern Europe some 200 million years ago.
They were fossilized into hard rock for building castles in the Middle age.
Spindle diagram showing Originating Era
Stromatoporoids
A
B
Stromatoporoids Showing calcareous Layers
Phylogenetics of Porifera• Diagnostic feature of the Porifera was the
presence of spicules,• Groups with a solid calcareous skeleton such as
the Archaeocyatha, chaetetids, sphinctozoans, stromatoporoids, and receptaculids were problematic.
• 15 extant species of sponges having a solid calcareous skeleton were recently added,
• With living sponges in hand, histological, cytological, and larval characteristics were observed.
• Calcarea and the Demospongia are more closely related to each other than they were to the Hexactinellida.
• chaetetids, stromatoporoids, and sphinctozoans were living with a fourth class was erected and called sclero-spongia,
• Sclero-spongia is not a natural monophyletic group and thus has being abandoned,
• The Archaeocyatha pose a special case because no living representative of this group has been discovered but their organization is consistent with that of living sponges.
• Phylogenetic analysis included archaeocyaths with other sponges and grouped them as sisters to the demosponges due to the presence of choanoflagellates.
• On the contrary, sponges only achieve collar cells after embryological development.
Phylogenetics of Porifera
Adaptive Radiation in Poriferans• The enormous diversification centres on
a unique ability of members to use a perfect water-current system to channel food, oxygen and eliminate waste via the same system.
• The proliferation of the flagellated
chamber observed in the leuconoid sponges favoured them because of the largeness in size of this group as compared to the asconoid and synconoid.
Morphology
Arrows shows water flow directions
Microscopic view of Porifera cells
Choanocytes (collar cells) They line the flagellated
canals and chambersThey are ovoid with one
end embedded in the mesohyl
Adjacent Microvilli are connected to each other by microfibrils
They act as a pump to bring water into the sponge
Food engulfed is passed to archeocyte for digestion
flagellum
Nucleus
Collar microvilli
Food Vacuole
Collagen - Support Collagen is found between the
inner canals and chambers Mesohyl
Amoeboid cells located in the mesohyl, have different roles:-
1.Archeocytes: motile in the mesohyl:– Phagocytize particles in the
pinacoderm,– Recieves particles for digestion
2.Sclerocytes: Specialized, secrete spicules
3.Spongocytes: Secrete spongin fibres for skeleton
4.Collencytes: Secrete fibrillar collagen
5.Lophocytes: Secrete large quantities of Collagen distinguishable from collencytes
Body wall: Support
Small Section through Sponge wall
Types of SpiculesDemospongiae &
Sclerospongiae secrete siliceous spongin silicon dioxide (SiO2).
Calcareous sponges secrete crystalline calcium carbonate (CaCO3) spicules with one to four rays
Collagen is stiffened by addition of microscopic mineral accretions or additional protein fibers (spongin) or both
Types of Spicules
Types of Canal Systems
Osculum
ChoanocytesSpongocoel
Ascon
Ostium
Osculum
Ostium
Sycon Leucon
Spongocoel
Choanocytes
Porocytes
Anatomy of Ascon & Sycon
Leuconoid Anatomy
• The most common network of water channels
Asconoids• Flagellated
spongocoels,• Simplest organization,• Small, branched and
tube shaped,• Spongocoels allow
water into the cells lined with choanocytes,
• Present only in Calcarea
• E.g. Leucosolenia, Clathrina canariensis,
Syconoids • Flagellated canals• larger editions of asconoids,• Tubular body but single
osculum,• Thicker & complex body
wall containing radial canals lined with choanocytes
• Spongocoels lined with epithelia & not flagella
• Water enters through dermal ostia and filters through Prosophyles,
• Food is forced through internal pores called apopyles,
• No branched colonies• E.g. Calcarea, hexactinellida
In flux & Out flux of Water in Syconoid
Leuconoids• Flagellated chambers,• Complex organization• Suitably adapted for
increasing size,• Forms large masses
with numerous oscula,• Flagellated cluster
chambers filled from incurrent canals, and opens into excurrent canals,
• Most are leuconoids,• Clear adaptive value,• E.g. Calcarea,
Classification
Phylum Porifera
Class Calcarea,
Class Demospongiae,
Class Hexactinellida,
Sclerospongiae (no longer
considered a class)
ClassificationClass Calcarea (calcareous sponges)
small, vase shaped, primitive group,
mostly drab coloured; a few are yellow, red, green, lavender,
all marine, especially shallow waters,
show all 3 types of canal systems; mostly asconoid canals,
spicules of CaCO3, needle shaped or 3-4 rayed, monaxons,
Grows in coloniesStraight spicules around the
osculum that discourages small animals from entering
Class Demospongiae (Most sponges)• Possess spicules made of silicon
dioxide (SiO2) or spongin or a combination of both
• Most sponges belong to this class (90%) Nearly all are leuconoid body type,
• 95% are living, encrusting plants• Mostly found on the continental
shelf in well oxygenated habitats• Spongilla spp. (Bath sponge),
present in midsummer and later form gemmules after disintegration
Class Hexactinellida (Glass sponges)
• Spicules are made of silica, • Usually found in deep water on soft
substrates in the tropics 200-1,000m.• Spicules are six- rayed, pointed and
have a lattice-like structure,• Cup, vase or urn shape,• Radially symmetrical,• Formed as one by trabecular net of
living tissues from fusion of pseudopodia of archaeocytes,
• E.g. Euplectella (Venus flower)
Reproduction in SpongesSEXUAL•Male & female gametes are formed (monoecious). •Archeocytes become eggs•Choanocytes filter sperm out of the water•Fertilization is involved.•Planktonic larvae or mini flagellated colonies are released to colonize new areas.•Most are viviparous
ASEXUALMarine sponges•Budding•Fragmentation•Regeneration
Freshwater sponges•Gemmules •Budding•Fragmentation•Regeneration
Development during Reproduction (Demosponges)
• Parenchymula larva is free – swimming,• Outward flagellated cells invaginates
and becomes the choanocytes,
Development during Reproduction (Calcarea)
A hollow blastula (Amphiblastula) develops with flagellated cells interiorly,
Blastula turns inside-out,
Flagellated end appears outward (micromeres),
Larger nonflagellated end (macromeres) turns into pinacoderm & Sclerocytes,
Flagellated cells become the choanocytes, archeocytes & collencytes
Larvae of SpongesAsexual•Asexual budding•Formation of internal buds/Gemmules by freshwater sponges•Regeneration: can regenerate from broken pieces•AllorecognitionSexual•Sexual usually hermaphroditic with male and female cells scattered throughout the connective tissue.
A Gemmule of Spongillidae
Human Impacts of Sponges
Bath sponges
•In use since bronze age (4000 yrs.)
•Holds up to X 35s its weight in water
•Takes 5 yrs. to reach marketable size
•Creates job opportunities for harvesters &
collectors
•Sponges were challenged by red tides and a fungal
disease that wiped out the sponge beds
•Synthetic sponges were introduced to the market
Human Impacts of SpongesProduction of a wide variety of bioactive compounds•Pharmaceuticals: Antibiotics, Asthma, Arthritis, Anticancer drugs, Chemicals that promote wound healing, Anti-inflammatories
Examplesantibiotics against bacteria such as E. coli and Staph aureus, e.g. Acyclovirfrom Caribbean sponge1st antiviral compound approved for human use fights herpes infections (in use since 1982), e.g. Vidabarine.may attack AIDS virus, e.g. a species of S/Pacific sponge produces chemicals that is bactericidal against Candida albicans (thrush and vaginal infections)
Human Impacts of Sponges
• In 2009, a new chemical derived from sponge has the ability to re-sensitize bacterial pathogens to antibiotics (Ensures loss of resistance to all antibiotics and die)
Material Science• The strongest glass structure derived
from Euplectella (Venus flower) is a source for study due to its strength
Aquarium Trade
End of Presentation End of Presentation
Thanks for ListeningThanks for Listening