Feeding in Sponges
• Particles larger than 50 micrometers cannot enter the
ostia and pinacocytes consume them by phagocytosis
(engulfing and internal digestion).
• Particles from 0.5 to 50 micrometres are trapped in the
ostia, which taper from the outer to inner ends.
– These particles are consumed by pinacocytes or by
archaeocytes which partially extrude themselves
through the walls of the ostia.
Feeding
• Bacteria-sized particles, below 0.5 micrometers, pass
through the ostia and are caught and consumed by
choanocytes.
– Since the smallest particles are by far the most
common, choanocytes typically capture 80% of a
sponge's food supply.
• Archaeocytes transport food packaged in vesicles from
cells that directly digest food to those that do not.
– At least one species of sponge has internal fibers
that function as tracks for use by nutrient-carrying
archaeocytes, and these tracks also move inert
objects.
To what class does this
example belong?
FEEDING
The series of 4 drawings shows one
food-transfer option. After a bacterium
is phagocytosed, the choanocyte
resorbs its collar and crawls off into the
mesohyl to distribute the digested food
products,possibly to an amoebocyte
Choanocyte with latex beads
on microvilli
Pseudopodia
(lamellipodia) wrapping
around larger beads
(1um) at the choanocyte surfaces
Carnivorous Sponges
• Some species in the family
Cladorhizidae capture and
digest whole animals.
– Capture small crustaceans with
their spicules, which 'hook onto'
and attach to crustacean
exoskeletons that they touch.
– Sponge cells then migrate around
the prey, and digestion takes
place extracellularly.
Cladorhizids- carnivorous
sponges
• Class Demospongia, Family
Cladorhizidae
• Discovered in 1995
• Abyssal and troglobytic
• Spicules act as hooks to snare
small invertebrates
Asbestopluma bihamatifera
Chondrocladia lyra
Chondrocladia
gigantea
Chondrocladia
lampadiglobus
Asbestopluma hypogea
Chondrocladia koltuni
Asbestopluma
Chondrocladia (Meliiderma) turbiformis
Reproduction and Development
• Asexual Reproduction
– Fragmentation
• See observations from lab exercise
– Buds
– Gemmules
• Overwintering bodies
• Thick covering of spongin
Spongilla lacustris
Gemmules
Gemmules
Spongilla gemmules
Sponge Gemmule
Overwintering protective body
of a sponge
Micropyle
Spicule
Mass of archaeocytes
Regeneration
• When sponge is pushed through fine mesh
strainer
– Cells will reaggregate and begin dividing to
reconstitute the sponge
– Cells from different species will not aggregate
• New sponges can grow from broken
fragments
• See lab exercise
Reproduction and Development
• Sexual Reproduction
– Highly variable
– Most sponges are hermaphrodites
• Both male and female gametes are produced
by the same individual
– Eggs from choanocytes and archaeocytes
– Sperm from choanocytes
• BUT most produce eggs at one time and sperm
at a different time
–What is the significance of this?
Reproduction and Development
• Sexual Reproduction
– Fertilization is external in some
• Takes place in the water
• “ovipary”
• Planktonic larvae
Reproduction and Development
• Sexual Reproduction
– Fertilization is internal in some
• Choanocytes trap sperm
• De-differentiate to amoebocytes = carrier cell
• Transport sperm to eggs in the mesohyle
• Larval development
– Some species retain the fertilized eggs
•
•
•
•
Early development is internal
Embryos are released as swimming larvae
Leave through excurrent pores or rupture parent
viviparous
Cross section, of Grantia showing larval
amphiblastula embedded in the body wall.
Sycon coactum water flow diagram
Sycon coactum - after squeezing through the
choanocyte layer the larvae are carried out of
the sponge in the water flow
X-section of amphiblastula larva showing
flagellated cells at anterior end and an internal
cavity, the blastocoel
Amphiblastula larva of Sycon sp.
Posterior cells later grow around to enclose the
flagellated cells, which come to face inwards. The
remnant of the blastocoel becomes filled with
mesohyl (a proteinaceous material). An opening,
the osculum, appears (at top of R-hand figure)
Reproduction and Development
• Larval development
– Larvae do not feed
– Larvae swim for about 24 hours
• Settle down
• Attach to substrate
• Metamorphose
– Larval cells migrate and differentiate into the
different cell types of the adult sponge
• Free-swimming larva are dispersal stage
– Make sure this is part of your 12 character chart!
Reproduction
• Reproduction
– Sexual
• Development
– Rearrangement of cells at time of settling
corresponds to gastrulation stage of all other
animals
– In some sponges outer flagellated cells are
lost at gastrulation
– In the Calcaria, flagellated cells dedifferentiate into mutipotent amoebocytes
Gastrulation
© BIODIDAC - Fins éducatives seulement / Educational use only
3 Types of Larvae
• Parenchymula Larva
–
–
–
–
Found in Demospongiae
Solid, covered with monoflagellated cells
Incubated until late in development
Repeated cleavage of the zygote takes place in
the mesohyl and forms a parenchymula larva
• Mass of larger internal cells surrounded by
small, externally flagellated cells.
• Swimming larvae enter a canal of the central
cavity and are expelled with the exhalant
current
Parenchymula larva
Larva of Amphimedon
queenslandica
3 types of Larvae
• Coeloblastula Larva
–
–
–
–
Found in calcareous sponges
Ciliated, hollow blastula
Short incubation
Complex development
• Micromeres
• Macromeres
– Intermediate stage = stomoblastula
• Consumes nutrient-rich amoebocytes
• Turns inside-out to form amphiblastula larva
Coeloblastula larva
Plakina
Scypha
The interior of the brood chamber of a sponge,
Amphimedon queenslandica, showing embryos
in the early phases of development.
Amphiblastula larva
Amphiblastula larva
of Sycon ciliatum
Settled sponge larva. The
flagellated cells have
invaginated.
3 types of Larvae
• Amphiblastula = Dispersal stage
– Swims for a short time and then settles
– Turns inside out so flagellated cells are inside
• Similar to gastrulation stage in animal
development
Comparative diagram of cleavage and
morphogenesis, leading to the larvae in
Calcaronea (Calcispongiae), Calcinea
(Calcispongiae), and Halisarcida
(Demospongiae).
a1–a4 Calcaronea. a1 incurvational
cleavage, a2 stomoblastula, a3
incurvation of the stomoblastula, a4
amphiblastula larva.
b1–b5 Calcinea. b1 polyaxial cleavage,
b2 coeloblastula, b3–b4 blastula cells
proliferation and differentiation, b5
calciblastula larva.
c1–c5 Halisarcida. c1 polyaxial
cleavage, c2 coeloblastula, c3–c4
blastula cells proliferation and
differentiation, c5 coeloblastula larva
Sponge Behavior
• Sessile
• No sensory organs
• Can respond to stimuli
– Touch or chemicals will cause ostia to
close (myocytes)
– Species recognition at cellular level
• Fragmented cells reaggregate according to
species
• Cells from different species do not reaggregate
Behavior
• No sense organs, nerves or muscles, but…
– Rate of flagellar beat can be infuenced by
currents; increases when current increases
– Communication among cells; maybe coordination
• Dilation of a channel may be propagated
throughout sponge
• Exposure to air or poisons can result in the
closure of a distant osculum to prevent
contaminating entire sponge
• No tissue connections, but temporary
communication channels can rapidly form
Behavior
• Examples
– In one species of encrusting sponge
• Osculum closes ~10 minutes after touching
sponge
• Closure may be done by myocytes, but it’s not
known how sponge reopens the osculum since
relaxing the myocyte fibers won’t stretch out the
sponge shape
– In a species of glass sponge
• Cannot change diameter of chamber but instead
the flagella of all chambers stop beating
• It is not known how stimulus is sent
Behavior
• A laboratory study confirms that hexatinellid
sponges Rhabdocalyptus dawsoni and
Aphrocallistes vastus arrest pumping in response to
mechanical stimuli and sediment
• Do this by propagation of electrical signals through
their syncytial layers.
– Signals are thought to be generated by membrane
depolarisation following contact with sediment or
mechanical stimulus such as a glass probe
– Leads to calcium influx into the choanocytes
accompanied by cessation of beating.
Behavior
Precursors to Nerves in
Sponges
• Found molecular building blocks of nerves
• Amphimedon queenslandica genome encodes many
genes that are used to create nerve cells in other
animals; these genes are all expressed during the
development of the Amphimedon larva.
Precursors to Nerves in Sponges
• Genes expressed in larval globular cells.
– Morphology and location of globular cells
suggest they may have sensory capacity.
• Located around outer surface of larva when it is
swimming around trying to find a settlement
site,
• One end of the cell sticks out into the external
environment while the other end of the cell is
inside the larva.
Precursors to Nerves in Sponges
– Morphology/location of globular cells
• The end of the globular cell that is outside the
larva could be sensing chemicals (smell or
taste) or surfaces (touch).
• The cell may then transmit this information to
the rest of the larva by releasing a chemical
from its internal end.
• Globular cells express gene for enzyme nitric
oxide synthase
– Globular cells produce nitric oxide
– Nitric oxide is a gaseous molecule that is often
used as a signalling messenger in animals.
Precursors to Nerves in Sponges
• Globular cells are implicated in neural
evolution
– Study found that many of the genes that make the
structural proteins in synapses are also
expressed in Amphimedon globular cells.
• Together these studies provide several These studies
provide several independent lines of evidence
supporting a relationship between sponge globular
cells and animal nerve cells.
While sponges do not have
true nerve cells, the
injection of the sponge
gene AmqbHLH1 into flies
caused them to develop
more sensory bristles on
their wings.
Read the article
Sponge Natural History
• Symbiotic relationships
– Mutualists: provide nutrients to sponges
• Dinoflagellates
• Bacteria
– Commensals
• Shrimps and other crustaceans
• Various worms
• Certain crabs grow sponges on their carapace
– Predators of sponges
• Sea turtles
• Gastropods
• Fishes
Sponge Natural History
• Defense mechanisms
– Biotoxins (allelochemicals)
• Kill nearby coral polyps or other encrusting
invertebrates
– Antimicrobial agents
– Many of these chemicals have potential
uses in industry and medicine
• Anti-inflammatory agents
• Anti-tumor agents
• Cardiovascular, respiratory, gastrointestinal
activity
Sponge Natural History
• Boring sponges
(demospongiae)
– Specialized cells chip holes
in bivalve shells and corals
– Can excavate complex
galleries in reef
Holes left by boring sponges
Boring sponges
• The “boring” is actually an etching and
is done by specialised amoebocyte cells.
• The cells crawl to spots on the shell and, by extending
“noose-like” protoplasmic strands between and
around the calcium-carbonate crystals making up the
shell, each cell eventually frees up a chip of shell by
secretion of a shell-dissociating enzyme.
• The enzyme appears to be carbonic anhydrase,
possibly released from granules located in the
cytoplasm surrounding the nucleus in each
amoebocyte. No acid appears to be involved. Cobb.
1969. Am Zool 9: 783; Hatch. 1980. Biol Bull 159: 135.
Boring sponges
Giant rock-scallop Crassadoma
gigantea with sponge, hydroid,
and coralline algal epibionts.
Chimneys of the boring sponge
Cliona californiana are visible
along the edge of the lower
valve. Inside, the shell is
hollowed into interconnected
galleries in which the sponge
lives. 0.5X
Sponge-Scallop Mutualism
• Boring sponges can be serious pests to oyster-growers.
– If the boreholes penetrate too deeply, the oyster
expends energy in repairing its shell - energy that
would otherwise go into production of edible flesh or
gametes for reproduction.
• Excavations in the shells of living abalones are repaired
by secretion of nacreous material, sometimes producing
beautiful iridescent “blister pearls”.
• Some mollusc shells with infestations, such as large
scallops, may be 5 times thicker than ones without.
Hansen 1970 Veliger 13:90.
Interior view of the shell of an
abalone Haliotis sp. showing
nacreous shell-secretions in the
form of rough blister pearls.
Shell valves of dead giant scallop
Crassadoma gigantea showing past
infestation of boring sponge Cliona. It
appears as if the sponge has left enough
original shell to maintain its integrity (i.e.,
stop it falling apart), but in reality it is the
scallop that has reinforced its shell from
the inside. Shells of Crassadoma can
become grossly thickened from this
cause 0.4X
Cliona
Boring sponges
Sponges Myxilla spp. grow on the
shells of swimming scallops Chlamys
spp. The scallop benefits most from
the relationship.
Sponge-Scallop Mutualism
Bloom. 1975. J Exp Mar Biol Ecol 17: 311
Sponge-Scallop Mutualism
Burns & Bingham. 2002. J Mar Biol Assn UK 82: 961
Sponge-Scallop Mutualism
Burns & Bingham. 2002. J Mar Biol Assn UK 82: 961
Sponge Shrimp
Synalpheus regalis
• Commensalism – use sponge as habitat
• Eusocial shrimp
– Colonies inhabit sponges found on coral reefs
• Discovered in 1996 in the Caribbean, off the coast of
Belize
– Behave like bees or ants, living in a colony and having
'castes' of workers, soldiers and a queen
• About 100 species of shrimp within this genus, at
least three of which have been found to have this
eusocial way of life
– Behavior is not known in any other marine animal
Synalpheus
Adult
Commensalism
Spongilla-fly larva on a
freshwater sponge
Mutualism
• Many sponges have
mutualistic relationships with
algae and/or cyanobacteria
• Algae provides sugar which
sponge consumes
• Sponge provides inorganic
nutrients to algae from its
wastes
• Sponge provides “home” for
algae
Spongilla lacustris
Mycale vansoesti with symbiotic
red algae
Evolutionary Considerations
• Probably arose from a flagellated
protozoan (Choanoflagellate)
• Very different from all other metazoans
– May have originated very early in
metazoan history or may be derived from a
protozoan ancestor that was different from
the one that led to the other metazoans
flagellum
Choanocyte or Collar cell
collar
microvillus
nucleus
Note similarity to group of
flagellated protozoans called
the Choanoflagellates!
Evolutionary Considerations
• Sponges now considered to be Metazoa
– Most simple Metazoa
– Subkingdom Parazoa fallen out of favor
• No longer considered to be related to
Placozoa
– This Phylum has only one genus Trichoplax
– Recent molecular data show Placozoa not closely
related to sponges but rather they are probably
related to Ctenophora
Phylogeny
• Animals (Metazoa)
– Porifera – Simplest metazoans
• Depends on where Placozoa are placed
• Previously written off as only phylum in Parazoa
– Not a monophyletic group
Microscopic metazoan parasites with an extremely reduced body
Simplest of all known animals
Evolutionary Considerations
• Sponges are ancient
– Recent fossils from China: 580 mya
• Spicules, soft tissues, embryos and larvae
– Molecular evidence shows a single origin for
metazoa
• Choanoflagellates, sponges and other metazoans
last shared a common unicellular ancestor in the
late Precambrian period more than 600 million
years ago.
– No phylum can be derived from present day sponges
• So sponges are a sister group to Metazoa
Amphimedon life history and metazoan phylogeny.
Choanoflagellate
M Srivastava et al. Nature 466, 720-726 (2010) doi:10.1038/nature09201
2010
Pterospongia - Hypothetical
choanoflagellate ancestor to
the metazoans.
Evolutionary Considerations
• Unique features
–
–
–
–
–
–
–
Cellular totipotency
Lack of true tissues
No basement membrane
No true digestive cavity
Lack of reproductive organs
Variety of reproductive modes
Lack of body symmetry and polarity
• Key synapomorphy (shared derived trait )
– aquiferous system that relies on flagellated cells
– defines the phylum
A Success Story
• Sponges owe their long term success to
– Cell totipotency
– Choanocytes
• Help circulate water
• Capture food particles
• Capture sperm and transport it to eggs
• An evolutionary dead end?
– No other metazoans appear to have
descended from the sponges
What changes have evolved during
sponge history?
• Morphological change
– Elaboration of flagellated chambers to
increase efficiency of water circulation
– Array of growth forms depending on
environmental conditions
• Flat encrusting sponges found where there is
heavy wave activity
• Still water forms are tall or hanging to increase
surface area to ensure already filtered water won’t
be recycled through sponge
• Deep water sponges show more variety
What changes have evolved during
sponge history?
• Physiological changes
– Correspond to ecological niches
• One opportunistic generalist readily colonizes
new sites, but never grows to maximum size
– Allocates energy to rapid maturation and
reproduction not to growth
• Another species forms permanent populations of
large individuals in poor environments
– Allocates energy to physical resistance but
slow reproduction
What changes have evolved during
sponge history?
• Physiological changes
– Carnivorous forms
• Deep sea species
• Hydroid-like: no choanocytes, ostia, oscula, or
water channels
• Recognized as sponges only by spicules and
the pinacoderm
What changes have evolved
during sponge history?
• Biochemistry
– Many have colors from symbiotic algae
– Also from pigment granules in
amoebocytes in some species
• May be aposomatic coloration and serve as
warnings to predators that the sponge is
poisonous
• May also use poisons to compete with other
sessile invertebrates for space
What changes have evolved
during sponge history?
• Biochemistry
– Boring sponges have specialized amoebocytes
that produce chemical secretions to remove
calcareous fragments from coral, clams,
scallops and any other calcareous material
• Fragments leave through excurrent water flow
system
• Function of boring is to gain shelter
• Boring causes considerable damage on reefs
How have sponges become
so successful?
• Survival: occupy many niches
• Large numbers
• Widespread: occupy many niches
• Independent cells have evolved a variety of
unusual biochemical specializations
• Can respond to their environment and behave as
functional units
A Question to Ponder
• The vast majority of sponges have the
leuconoid body plan.
– What is the advantage of the more
complex body plans (syconoid, leuconoid)
over the simple asconoid body plan?
• See Table 4.1 for a hint
Diversity
• About 7-15 K species
• 98% marine
– Littoral has highest diversity (area between high
and low tide lines)
• Mostly encrusting species
– Benthic species live on the bottom
• Benthos = organisms that live on the bottom
• Since the substrate is often soft and silty,
sponges that live here are often upright and tall
to avoid being buried by sediments
– Coral reef species are often quite large
• Make up large part of reef biomass
• A few freshwater species
A
B
A = high water, B
= low water
ocean: zonation
Encrusting sponges
Benthic Sponges
Barrel sponge
Unidentified tube
sponges
Reef Sponges
Sponge Uses
• Hippospongia and Spongia, have soft, entirely
fibrous skeletons.
– Early Europeans used soft sponges for many
purposes including padding for helmets, portable
drinking utensils and municipal water filters.
– Until the invention of synthetic sponges, they were
used as cleaning tools, applicators for paints and
ceramic glazes and discreet contraceptives.
• By the mid-20th century, over-fishing brought
both the animals and the industry close to
extinction.
Sponge Uses
• Research foci
– Models for the study of cell junctions
– Cell surface proteins that mediate cellular
recognition – very simple immune system
– Bioactive compounds
• Sponge used by Maoris of New Zealand promotes
wound healing and may have anti-inflammatory
agent
• Antimicrobial agents
Fun Facts
• Dolphin sponging
– A report in 1997 described use of sponges as a
tool by bottlenose dolphins in Shark Bay. A dolphin
will attach a marine sponge to its rostrum, which is
presumably then used to protect it when searching for
food in the sandy sea bottom. The behaviour, known
as sponging, has only been observed in this bay, and
is almost exclusively shown by females. A study in
2005 concluded that mothers teach the behaviour to
their daughters, and that all the sponge-users are
closely related, suggesting that it is a fairly recent
innovation.
Dolphins use sea sponges to forage
for fish and that daughters learn the
trick from their mothers.
Help Squidward and Mr.
Krab fill in their review chart
about Sponge Bob’s phylum
characteristics