Warm up.
Name that symmetry
Answer: Bilateral
Answer: Radial
Answer: Radial
Sea sponge
Answer: Asymmetry!
Asymmetry – non-symmetrical
Phylum: Porifera
"I drink no more than a sponge"
Francis Rabelais
Phylum Porifera
• From Greek ‘poros’ meaning ‘passage’ or ‘pore’
Sponges have tiny openings all over their body
• Therefore Porifera = “pore-bearers”
• Most ancient and primitive of all animals
• Estimated 5000-10000 species
• Most sponges are marine, some live in freshwater
Where are they on the tree of life?
• You tell me?
“I never wanted to be different; I just
wanted to be me”
• Sponges are different than other animals.
• Originally thought to be plants because
“sessile”
• Have no: Mouth, head, muscles, nervous
system, digestive tract, circulatory organs, true
tissue layers, organ system.
• Long thought to be an evolutionary dead end
however recently believed to be at the base of
the animal tree of life.
Sessile: “fixed in one place”
What do they have?
Why are they an animal?
• Collagen- all animals use collagen as an
essential structural protein
• Animal embryonic development
• “Motility” of most cells within the sponge
Motile
Structure and Function in Porifera
-The 4 Cells
• Epidermal cells
• Pore Cells
• Collar Cells (choanocyte)
• Amoebocytes
Epidermal
- Flat cells form the outer covering.
- Respire and excrete via diffusion.
Pore cells
- Cylindrical cells which allow water and food to
enter the sponge
- The flow of water is driven by current and by
collar cells
Collar cells (choanocyte)
- Inner cell layer of a sponge
- Have a flagellum which
draws water into the sponge
-flagellum also drives food
into the collar where they are
ingested into the cell body
Amoebocytes
• amoeba-like cells that crawl around the
jellylike inner layer of the sponge
• Deliver food and O2
• Absorb nutrients and remove wastes
• Make SPICULES which create sponge skeleton
• Carry sperm to eggs
n
Activity
• With a partner try and remember the 4 cell
types
• Draw the four cell types
• Label their parts.
• Write brief definition of what they do
• Gallery walk (see other drawings get ideas
how other people do their work)
How does a sponge stay standing?
• Spicules
• Spongin
Head to Head
Spicules
Spongin
• Created by Amoebocytes
• Made from either:
-chalklike calcium carbonate (CaCO3)
-or glasslike silica (SiO2)
• Form the delicate skeleton of the
sponge
• Softer sponges (like the
ones you can buy to use in
the bath) are made up of
fibrous proteins called
spongin.
• Some sponges contain both
spicules and spongin
Spicules
Spongin
Evolution of Spicules
Other key words
• Spongocoel – hollow body in the sponges
interior. (think coelom)
• Osculum- Opening where water exits the
sponge
• Spicules – the skeleton of the sponge (more
later)
How does a sponge eat?
• ..\..\..\Lesson Videos\Biology 11\Sponge
Feeding.mov.flv
How does a sponge eat?
• Sponges are filter feeders
– they sift microscopic food particles from the
water that passes through them
• All digestion is intracellular
• Food particles stick to the collar cells
Collar cells either digest the food or pass them on
to the
? (what else digests/delivers food)
Amoebocytes
The water flowing through a sponge serves as its
respiratory, excretory, and circulatory system.
• Sponges pump huge amounts of water
through their body every day
• Roughly one tonne water per ounce of food
Reproduction
Asexual reproduction
• “Budding” – a small growth
forms and falls off the sponge
starting a new sponge
• “regeneration” Sponges can
regenerate from broken pieces
• “Gemmules” sphere-shaped
collections of amoebocytes
surrounded by spicules. They
leave sponge, settle, and wait
for improved conditions
Sexual reproduction
• Hermaphrodites (both male
and female sexual organs)
• Most fertilization is
hermaphroditic
• “Broadcast” method of
sperm release. Masses of
sperm released into water
• Amoebocytes carries sperm
to egg when received.
Gemmulles
• “Little gems of life”? “Survival pods”?
• Remember it your way.
• Sphere-shaped collections of amoebocytes surrounded by
spicules
• leave sponge, settle,
and wait for improved
conditions
Gemmules
• Can survive extreme temperatures or drying
out
• Some are resistant to freezing
• Full of amoebocytes which can grow into any
type of cell necessary for survival
• Why would sponges have evolved Gemmules?
Here comes the Motility
Flagellated larvae
•
•
•
•
A sponges larvae have flagellum
Leave via
?
Osculum
Drift/ swim to their new home
• ..\..\..\Lesson Videos\Biology 11\Sponge
Spawning.flv