Download Phylum Porifera (Sponge)

Phylum Porifera
The Sponge
Sponges are
• Simple, multi-cellular animal with pores
• Asymmetrical, no organs or tissues
• Central cavity with opening called a
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osculum
Invertebrates without any specialized
features
Filter-feed on plankton, digestion by
amebocytes
Reproduction can be sexual or assexual
Meroplanktonic larvae, sessile adults
Sponges are usually grouped according to
the type of spicules into three classes:
• Class 1: Calcarea (Calcispongiae) Spicules
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composed principally of calcium, are monoaxon or
three or four branched,
Class 2: Hexactinellida (Hyalospongiae) Spicules
composed principally of silica, are 6-rayed,
Class 3: Demospongiae (Siliceous) Spicules or
horny fibers or both are present. If spicules of silica
are present in an intertidal form, the sponge
probably belongs to this class. Spicules, if present,
are never six-rayed.
Sponge Reproduction
• Sexual
– Produce gametes from specialized
collar cells
– Most sponges are hermaphrodites.
• Broadcast spawning is when the
sperm is released into the water
• Eggs are retained in the sponge
for fertilization to take place.
• Larva are released to develop
into sponges.
• Asexual
–Budding
–Fragmentation
–Gemmule Formation
(internal buds – rare in
marine)
Gemmules
• Large mass of archaeocytes
• Formed during harsh conditions
• Environmentally resisitant
• When ready, archaeocytes are released
to form new sponges.
Sponge Anatomy
Sponge
Cell
Wall
Spicules
TYPICAL SPONGE FEEDING
• Water flowing through sponges provides food and
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oxygen, as well as a means for waste removal. This flow
is actively generated by the beating of flagella. The
water movement through some sponges is aided by
ambient currents passing over raised excurrent
openings. This moving water creates an area of low
pressure above the excurrent openings that assists in
drawing water out of the sponge.
Sponges are capable of regulating the amount of flow
through their bodies by the constriction of various
openings.
The volume of water passing through a sponge can be
enormous, up to 20,000 times its volume in a single 24
hour period.
• In general, sponges feed by filtering bacteria
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from the water that passes through them.
Some sponges trap roughly 90 percent of all
bacteria in the water they filter. Other sponges,
in particular hexactinellids, appear to be less
efficient at capturing bacteria and may specialize
in feeding on smaller bits of organic matter. Still
other sponges harbor symbionts such as green
algae, dinoflagellates, or cyanobacteria, from
which they also derive nutrients.
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