Phylum – Porifera
The Sponges
Copyright cmassengale
Taxonomy
• Kingdom – Animalia
• Subkingdom – Parazoa (lacks tissues)
• Phylum – Porifera (pores)
Characteristics
o Simplest of all animals
o Contain specialized cells
but no other organization
level
o Most are marine
o Saltwater sponges are
brightly colored
o Freshwater sponges are
small and dull green color
o Size – 2 meters to 2 cm
Characteristics
o Porifera means porebearing
o Water enters through
pores bringing in food
and oxygen
o Filter feeders on
plankton
o Osculum – large opening
at the top where excess
water leaves
WATER OUT
Water Flow
Through the
Sponge
WATER IN
Osculum
Water Flow Through Sponge
Characteristics
o Asymmetrical
o Sessile as adults
(attach to rocks)
o Free-swimming larval
stage called
Dipleurula
o Also reproduce by
fragmentation (pieces
break off & form a
new sponge)
Sponge Body Structure
o Inside body cavity of sponge is hollow
o Called the Spongocoel
o Have 2 cell layers:
 Outer epidermis
 Inner endoderm
o Jelly-like material between cell layers
called mesenchyme
•Choanocytes line the
gastrovascular cavity &
capture food
•Amebocytes
(archaeocytes) digest
& distribute food
Specialized Cells
• Choanocytes (collar
cells) line inside of
body cavity
(spongocoel)
• Have flagella that
spins to pull in water
& food
• Collar traps plankton
(food) from water
Collar
Other Specialized Cells
o Amebocytes
(archaeocytes):
• Pick up food from
choanocytes
• Finish digestion
• Move through the
mesenchyme & take
food to other cells
Other Specialized Cells
o Porocytes:
• Water enters
the sponges
• Contain epithelial
cells
• Contract
the pores
to close
Skeletal Structure of the Sponge
• Skeleton made of network of
protein fibers called Spongin
• Spicules are hard spear or starshaped structures
• Spicules made of CaCO3
(limestone) or silica (glass)
• Made by Archaeocytes
(amebocytes)
Sponge Skeletons
Silica Spicules
Limestone Spicules
SPONGIN
Sponge Skeletons
SPICULES
VENUS
FLOWER
BASKET
Sponge Feeding & Digestion
o Sponges filter food
from the water
o Bacteria, protozoa,
algae…
o Choanocytes engulf
food with flagella and
digestion begins –
intracellular digestion
Sponge Feeding & Digestion
o Nutrients are
released to the
amebocytes
(archaeocytes) which
take them to all cells
in sponge
o Undigested food
leaves with water
through osculum
Sponge Reproduction
o Sponges can
regenerate (regrow)
lost body parts
through mitotic cell
division (asexual)
o Sponges also
reproduce asexually
by budding
Sponge Reproduction
o Sponges are
hermaphrodites (produce
both eggs & sperm)
o Sponges reproduce Sexually
by releasing sperm into the
water from the Osculum
o Sperm enters sponge
through porocytes and
fertilize the eggs internally
o Fig. 26.9
Sponge
releasing eggs &
sperm
Surviving Harsh Conditions
o Gemmules are specialized buds made
to survive harsh weather (hot or
cold)
o Contain food, amebocytes, and a
protective covering of spicules
o Released when a sponge dies
o Resist dessication (drying out)
o Become adult sponge conditions
become favorable
Circulation, Respiration, Excretion
o All processes are carried out by
the movement of water through the
sponge - DIFFUSION
Branching Tube Sponge
Stove Pipe Sponge
Vase Sponges
Barrel Sponges
Ball Sponges
Rope
Sponges