Transcript Porifera, Cnidaria, Worms

Phylum Porifera
Chapter 26
General Characteristics
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No mouth, gut, specialized
tissues or organ systems
Multicellular
Kept rigid through deposits of
calcium carbonate, silica or
spongin
Reproduce asexually through
budding and/or sexually
through sperm and egg
Water enters through the
central cavity, deposits
nutrients, and leaves through a
hole called the osculum (filter
feed)
sessile
majority are marine (salt water)
species, ranging from tidal
zones to depths exceeding
8,800 metres
Gemmules
• When conditions deteriorate,
for example when
temperatures drop, many
freshwater species and a
few marine ones produce
_______________,
• “survival pods,” of
unspecialized cells that
remain dormant until
conditions improve and then
either form completely new
sponges or re-colonize the
skeletons of their parents.
Ecological Importance
• Environmental
>____________________________________
• Economical
>____________________________________
• Medicinal
>___________________________________
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Phylum Cnidaria
General Characteristics
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Have a mouth and gastrovascular cavity
with digestive enzymes
Lacks an _______________(excretory
system) and _______________________
Simple nervous system (nerve nets and
sensory cells – statocysts and ocelli)
Soft bodied with stinging tentacles around
their mouth
Carnivores (capture prey with their
nematocysts)
Asexual reproduction: _________________
Sexual reproduction occurs in medusa
form (depending on the species,
fertilization is external – chance encounter
or inside an egg-carrying medusa)
Two Body Forms
1. Polyp
– sessile flowerlike
2. Medusa
– motile bell-shaped
Depending on the type of cnidarian, their life cycle may include both body
types.
Three Classes of Cnidarians
1. ___________________
-size: few cm to a
metre
-freshwater
-polyp and short
medusa phase
-usually separate
sexes, but a few are
hermaphroditic
ex: hydras
Portuguese Man-of-War
Three Classes of Cnidarians
2. ____________________
-medusa is large and
long-lived
-polyp is a tiny larval
stage
-can grow up 2m in
diameter
-most nematocysts are
harmless to humans
ex: Jellyfish
Three Classes of Cnidarians
3. _________________
-polyp stage only
-many shallow water
species depend on
photosynthetic
symbiotic
relationships
-can grow up to 1m
ex: sea anemones
and corals
Ecological Importance
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Unsegmented Worms
Phylum Platyhelminthes and Phylum Nematoda
General Characteristics
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• Simple nervous system
with sensory organs and
a simple brain in their
anterior region (head)
• Has 3 germ layers
(ectoderm, mesoderm
and endoderm)
Phylum Platyhelminthes
(Flatworms)
-Carnivores that feed on tiny aquatic animals,
scavengers feeding on recently deceased animals,
or parasites feeding on blood or tissue fluids
inside their hosts body
-Use a pharynx to suck food into a gastrovascular
cavity
-Undigested food is expelled through the mouth
(____________________________)
-Lack a specialized circulatory and respiratory system.
Depend on diffusion to transport oxygen and
nutrients to their tissues and wastes out
-Have light sensitive organs ( ____________________)
Examples:
>Class Turbellaria: __________________________
>Class Trematoda: __________________________
>Class Cestoda: ____________________________
Phylum Nematoda
(Roundworms)
• Have a ____________
and an ______________
• Simple nervous system
• Bilateral symmetry
• Free-living
• Mostly carnivorous
• Breathe and excrete
their wastes through
their body walls via
diffusion
• Reproduce ___________
Ecological Importance
• Mostly negative – disease causing in
humans and animals
– Example: Trichinella, elephantiasis, Ascaris, etc.
Your Task: read and make notes pages 570-578
answer questions #1-5 pg 578