Phylum Porifera
Sponges
chapter 7
https://www.shapeoflife.org/video/sponges-origins
Chapter 7
Sponges
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Sessile - attached to bottom or surface
Phylum Porifera “pore bearing”
Simplest multicellular animals
Cells are specialized (but lack true tissues and organs)
If experimentally separated, some sponges can even
regroup and form a new sponge.
• https://www.youtube.com/watch?v=N462jZFr13k
4 Types of Cells
• Outer surface covered with pinacocytes (flat cells) and
porocytes (tube-like pore cells)
• Collar cells (Choanocytes) - have flagella that create
currents through the sponge and a thin collar that traps food
particles
• Amoebocytes –
wandering cells that
transport nutrients
and secrete support
structures.
How sponges eat
• Filter feeders – filter food from water
• Ostia – tiny pores on the surface of the
sponge that allow water to enter
• Atrium – inner chamber lined with
collar cells
• Collar cells – trap food particles for consumption
• Amebocyte cells carry the nutrients to the sponge's
other cells
• Osculum – large opening on top of sponge where the
water exits
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https://www.youtube.com/watch?v=pTZ211cIjX8 (2:41 – filter feeders with dye)
Structural Support
• Spicules – made of silica or calcium carbonate,
different shapes and sizes
– Structural support
– Deter predators
– sharp
• Spongin – a skeleton of tough, elastic fibers
made of a protein
– flexible
Glass sponges, contains
spicules
Contains Spongin
“bath sponge”
Sponge Complexity
• Simple sponges have a single osculum
• Complex sponges have many oscula
Sponge Complexity
Asexual Reproduction
• Branches or buds break off and grow into
separate sponges identical to original one
Sexual Reproduction
• Most sponges are hermaphroditic (both male/female)
• Sponge gametes (sex cells) develop from specialized
collar cells
• Spawning – release sperm into water
• Sperm enter sponge through ostia and internal
fertilization takes place
Metamorphosis
• Early stages of development take place inside the
sponge
• A tiny flagellated sphere of cells (larva) is released out
of an osculum into the water
• Planktonic larva settles on the bottom and changes
into an adult sponge (metamorphosis)