We are going to view several segments of the fantastic BBC documentary by Sir David Attenborough.
There are some four million kinds of animals and plants in the world - four million different solutions to the problems of staying alive. This is the story of how a few of them came to be as they are.
Life on Earth, the result of a three-year, 1.3 million mile odyssey to all seven continents, is the story of how a few of those life forms came to be as they are, not as isolated oddities but as elements in a long and continuous story that began billions of years ago.
BYERLY'S NOTES
Section 2: Building Bodies - First signs of life in the seas. (13 minutes)
Download Section2.doc
2.1 Flatworms
- Long and flat
- Distinct beginning and end
- Adapted to round – better suited for conditions
2.2 Mollusks
- Mollusk Adaptations (500-600 mya Early November)
- Well developed head
- Tentacles
- Eyes
- Scraping tongue (radula)
- Muscular foot
- Scallop mobility and eyes
2.3 Nudibranchs
- free swimming
- reducing or losing shells
- defense = foul slime
- colors to “warn predators” instead of as camouflage – interesting
- more complex and larger than flatworms
- developing special breathing apparatus – gills
- they hunt jelly fish
2.4 Nautilus and Squids
- Another group of mollusks develop into nautilus
- 500 mya (November)
- Squids are descendants of nautilus who have almost completely lost their shells
2.5 Starfish and their relatives (1 minute)
- Secret of success = mobility of larvae!!
- Ensures continued survival
2.6 Segmented Animals – Horseshoe Crab
- Specialization = exoskeleton – allows animals to move on land as well as water
- 400 mya (mid November)
2.7 Robber Crabs
- Adaptations – breathing and eating on land.
- Other movers from sea to land?
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