how many lines of symmetry?
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How many lines of symmetry?. Fertilized egg. Zygote is one diploid cell made by the fusion of the sperm and egg. In humans this is internal fertilization within the fallopian tubes. Many other organisms have external fertilization where the egg and sperm are both released outside the parent. - PowerPoint PPT PresentationTRANSCRIPT
How many lines of symmetry?
Fertilized egg
• Zygote is one diploid cell made by the fusion of the sperm and egg.
• In humans this is internal fertilization within the fallopian tubes.
• Many other organisms have external fertilization where the egg and sperm are both released outside the parent.
blastula
8 cell stage (blastocyst)morula
gastrula
Germ layers
• 3 kinds:– Ectoderm– Mesoderm– Endoderm
– Layers of cells that work together to form specific tissues.
– Sponges (0), cnidarian (2), others (all three)
Body plans: Coelom
If three germ layers, then….
PoriferaSponges
Sessile AdultsMotile Larvae
Assymetry
Very Primitive- “barely” multicellularClassified by hard skeletal spines called spicules
spicules
Investigating sponges
http://www.youtube.com/watch?v=BW05vMziy2o
Sponges spawning
http://www.youtube.com/watch?v=SHJOu9PjKyU
Body of sponge• Osculum: opening at the top• Ostia: openings in the wall of sponge
Cnidaria• Alternation of generations:
Most have both stages in life cycle
• Medusa: motile/sexual/tentacles down/mouth down
• Polyp: sessile/asexual/ mouth up/tentacles up
Characteristics of Cnidaria
• Nematocyst stingers Nerve net (no brain)
• Hydra• Hydra catching food: http://
www.youtube.com/watch?v=Kukv0AtIVdU&feature=related
• Hydra; http://www.youtube.com/watch?v=yqXkaZwiu6s&feature=related
• http://www.youtube.com/watch?v=v9j9iO6Zy4o&feature=PlayList&p=E9E1093124E2F9C9&playnext=1&index=3; jellyfish movement
• http://www.youtube.com/watch?v=M9MMp7QX6e0&feature=PlayList&p=E9E1093124E2F9C9&playnext=1&index=2 polyp stage
Cnidarians
• Portuguese Man-of-War are colonies of four kinds of highly modified polyps: feeding polyps, reproductive polyps, etc..
• Hydra• Hydra catching food:
http://www.youtube.com/watch?v=Kukv0AtIVdU&feature=related
Cnidaria: hydrozoa
Phylum Ctenophora: close relatives to cnidaria but jelly instead of
stingers• Comb jellies
http://www.youtube.com/watch?v=G7WT81ukHZE
Platyhelminthes FLATWORMS
• Tapeworms, Flukes (parasites), free swimming (planaria)
Cephalization
Notice the front end has sensory organs (HEAD?)
Most are parasitic and don’t have cephalization, but platyhelminthes were first to have it.
Characteristics
• Acoelomate/
• No coelom/organs
• Highly branched• Digestive system as
they have no circulatory system
Flatworm videos
• http://www.youtube.com/watch?v=voMKJea91gg free living flatworm
• http://www.youtube.com/watch?v=Ich4Y_K6GuM&feature=PlayList&p=E9E1093124E2F9C9&playnext=1&index=11 planaria eating
• http://www.youtube.com/watch?v=T6pAfQInf2c tapeworm in intestine
Fluke
• All parasitic• Most famous is the Sheep liver fluke that
causes schistosomiasis.• Over 100 million in the world have this
fluke/disease.