CHAPTERS 12 & 13
PORIFERA, CNIDARIA AND
CTENOPHORA
PHYLUM PORIFERA (PORE-BEARER)
A. Characterisitics:
Usually asymmetrical, sometimes radially
symmetrical
Contain no tissues, organs, or muscles
I.
Filter feeders: water moves in through the
pores into the central body cavity and
out through the osculum.
PHYLUM PORIFERA
• supported by a skeletal system consisting of
needle-like spicules composed of silicon salts
(glass) or calcium carbonate (CaCO3), and/or
a soft and pliable skeleton made of organic
fibers composed of fibrous collagen or
spongin.
COMPOSITION OF SKELETON IS
USED TO CLASSIFY PORIFERA
• Contain three cell types:
• 1. pinacocytes: line the outer surface, may be mildly
contractile
2. mesenchyme
cells: amoeboid cells that move
about in the mesohyl (middle cell layer)
specialized for reproduction
secreting skeletal elements
transporting and storing food
form contractile rings around openings (pores)
• 3. choanocytes: (collar cells) cells with
flagella that create water currents and the
collars the filter food out of the water
(phagocytosis).
MAINTENANCE FUNCTIONS
•B. Digestion: the break down of
food occurs inside food
vacuoles/lysosomes (intracellular)
•Excretion: nitrogenous waste
occurs by diffusion
•Respiration: O2 and CO2 gas
exchange occurs by diffusion
•Endocrine System: may use chemical
messages for communication among
cells
REPRODUCTION
1.Skeletal: spicules or spongin
2.Reproduction *****(know in detail)
• a. Sexual reproduction:
 Sponges are monoecious (produce
both sex cells in a single individual) but
produce eggs and sperm at different
times.
• Zygote develops into a free-swimming larva
that will settle to a substrate after 2 days.
• b.Asexual reproduction:
• the formation of gemmules (resistant
capsules that contain masses of amoebalike mesenchyme cells)
• gemmules are formed when the sponge
dies or is under environmentally stressful
conditions.
• gemmules are formed in the mesohyl
• Asexual reproduction is also regeneration (an
internal budding process producing identical
clones of the parent).
3 DIFFERENT TYPES OF ANATOMY
• C. Morphology of Sponges ****
• Body formation is based on the pathway
of water currents flowing through the
sponge
3 CANAL TYPES:
• 1. Asconoid sponges: simplest body plan,
water moves in ostia (pores)  spongocoel 
out a single osculum
• 2. Syconoid sponges: water moves in ostia 
incurrent canals  radial canals 
spongocoel  out a single osculum
• Leuconoid sponges: most complex with a
branched canal system,
• water moves in ostia  incurrent canal 
excurrent canals  smaller spongocoel 
out multiple osculum
CNIDARIA
• “Stinging celled”
• A. Characteristics:
• Radial or biradial symmetry
• Diploblastic (2 tissue layers), endoderm and ectoderm
with gelatinous mesoglea in between
• Gastrovascular cavity (GVC)
• Nervous system: nerve net
• Have Cnidocytes which contain special organelles
called nematocysts for attachment, feeding and
defense, often contain toxins.
MAINTENANCE FUNCTIONS
• Digestion: begins in the gastrovascular cavity (GVC) and
is completed in food vacuoles, undigested waste exits
out the mouth (intracellular), no anus present
• Excretion: GVC also functions in the exchange of
nitrogenous waste through diffusion
• Respiration: the exchange of gases (O2 & CO2) also
functions through diffusion of the GVC
• Reproduction: GVC functions to release the
gametes (egg and sperm cells)
• Skeletal & locomotion: support and movement
are aided by a hydrostatic skeleton (the GVC
fills with water).
• Muscular: contraction of epitheliomuscular cells aid
in movement.
• C. Reproduction ***
• Exhibit alternation of generations
• Each generation is a different body form
2 DIFFERENT FORMS:
• polyp
• asexual and sessile
• cylindrical body with a mouth at the top surrounded
by food-gathering tentacles
• reproduces by budding (the bud is the offspring of
the polyp and becomes the next generation =
medusa body plan
MEDUSA
• medusa
• dioecious (separate sexes), sexual, and free-swimming
• body shaped like an inverted bowl with the tentacles hanging down around
the mouth underneath
• formed by budding from a polyp
• has sexual reproduction by releasing egg (female) and sperm (male) into
the water
• zygote develops into a planula larva (the
offspring)
• Larva plants itself into the ground and will grow
to become the next generation of polyp.
• D. Classes
• Hydrozoa: ie) Obelia, Hydra, Portuguese manof war (phasalia)
• 2. Scyphozoa: (true jellyfish) ie) Aurelia,
Stinging nettle
Cubozoa: (medusa is cuboidal) ie) Sea wasp
• 4. Anthozoa: ie) sea anemones and stony and
soft coral
• 3.
CTENOPHORA
• III. Phylum Ctenophora
• A. Characteristics
• Biradial symmetry
• Diploblastic with gelantinous mesoglea
• Monoecious
• Gastrovascular cavity
• Nerve net
• Adhesive structures called colloblasts that
capture prey.
• Eight rows of ciliary band, called comb
rows, for locomotion.
• Examples: Pleurobranchia, Boroe
• (Sea Fan and Sea Pin)