power2 - 10/27/2009 1 Why do we see such a spectacular...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
10/27/2009 1 1 Why do we see such a spectacular radiation of animals during the Cambrian period? • 543-490 million years ago • First appearance of shells, hard skeletons = much greater chance of fossilization • Emergence of predators 2 Why do animals have skeletons or hard coverings? 3 Muscles are precisely placed in both endoskeletons and exoskeletons for movement of segments relative to one another 4 Predatory mollusks dominated during the Paleozoic era, and included ancient Ammonites 5 Major groups of animals with hard body parts: • Mollusks – one or two external shells • Arthropods – jointed exoskeleton • Echinoderms – endoskeleton of plates • Vertebrates – endoskeleton of bones 6 The Mollusks evolved from worm-like creatures that developed a hard shell made primarily of calcium carbonate Phylum Mollusca
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
10/27/2009 2 7 Mollusca Class Polyplacophora (Chitons) In Chitons, the shell is segmented 8 Clams filter-feed via a siphon system, and have a strong foot for digging
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 02/10/2010 for the course BSC 2010 taught by Professor Essig during the Spring '10 term at University of Southern Maine.

Page1 / 6

power2 - 10/27/2009 1 Why do we see such a spectacular...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online