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Phylum PoriferaChapter 26
General Characteristics• 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>___________________________________
____________________________________
Phylum Cnidaria
General Characteristics• • • 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 hermaphroditicex: 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 humansex: Jellyfish
Three Classes of Cnidarians
3. _________________-polyp stage only-many shallow water species depend on photosynthetic symbiotic relationships-can grow up to 1mex: sea anemones and corals
Ecological Importance
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Unsegmented WormsPhylum Platyhelminthes and Phylum Nematoda
General Characteristics
• _____________________• _____________________• 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