Lecture Slides for Phylum Porifera (Sponges) ZLY

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ZLY 303
Phylum Porifera
Phylum Porifera (Sponges)
 5000 - 90000 spp.
 mostly marine some freshwater
 none terrestrial
 3 classes, most important
 distinctions are skeletal
 Most primitive animal group
Distribution
There 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
Simplicity
They 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 availability
Therefore environment plays significance in
growth patterns.
Sponge Biological Associations
Excoriations by sponges into shells and Carapace of
Bivalves and Brachipods
Abundance of fossil records
In 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.
Phylogenetics of Porifera
• chaetetids, stromatoporoids, and sphinctozoans were
living with a fourth class was erected and called sclerospongia,
• 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.
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
flagellum
canals and chambers
They are ovoid with one end
embedded in the mesohyl
Collar
microvilli
Adjacent
Microvilli
are
connected to each other by
microfibrils
 They act as a pump to bring
Food
Vacuole
water into the sponge
Nucleus
Food engulfed is passed to
archeocyte for digestion
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 Spicules
Demospongiae &
Sclerospongiae
secrete siliceous
spongin silicon
dioxide (SiO2).
Calcareous sponges
secrete crystalline
calcium carbonate
(CaCO3) spicules
with one to four
Collagen is stiffened by addition of microscopic
rays
mineral accretions or additional protein fibers
(spongin) or both
Types of Spicules
Types of Canal Systems
Osculum
Osculum
Choanocytes
Porocytes
Spongocoel
Choanocytes
Spongocoel
Ostium
Ostium
Ascon
Sycon
Leucon
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)
Classification
Class 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 colonies
Straight 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 Sponges
ASEXUAL
Marine sponges
• Budding
• Fragmentation
• Regeneration
Freshwater sponges
• Gemmules
• Budding
• Fragmentation
• Regeneration
SEXUAL
• 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
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 Sponges
Asexual
A Gemmule of Spongillidae
• Asexual budding
• Formation of internal
buds/Gemmules by
freshwater sponges
• Regeneration: can regenerate
from broken pieces
• Allorecognition
Sexual
• Sexual usually
hermaphroditic with male
and female cells scattered
throughout the connective
tissue.
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 Sponges
Production of a wide variety of bioactive compounds
• Pharmaceuticals: Antibiotics, Asthma, Arthritis,
Anticancer drugs, Chemicals that promote wound
healing, Anti-inflammatories
Examples
antibiotics against bacteria such as E. coli and Staph
aureus, e.g. Acyclovir
from Caribbean sponge
1st 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
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