LECTURE8BODYPLANSANIMALS

- The animal kingdom probably evolved from a colonial flagellated protist This ancestor was most likely a that lived over 700 million years ago in

Info iconThis preview shows pages 1–19. Sign up to view the full content.

View Full Document Right Arrow Icon
Background image of page 1

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

View Full DocumentRight Arrow Icon
a colonial flagellated protist. This ancestor was most likely a that lived over 700 million years ago in the Precambrian era. The animal kingdom probably evolved from
Background image of page 2
Background image of page 3

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

View Full DocumentRight Arrow Icon
Background image of page 4
This protist was probably related to choanoflagellates, a group that arose about a billion years ago. Modern choanoflagellates are tiny, stalked organisms inhabiting shallow ponds, lakes, and marine environments.
Background image of page 5

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

View Full DocumentRight Arrow Icon
If we could trace all the animals lineages back to their origin, they would converge on a common ancestor ( mono- phyletic ).
Background image of page 6
What are the advantages and disadvantages of multicellularity?
Background image of page 7

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

View Full DocumentRight Arrow Icon
One advantage of multicellularity is that now you can produce larger (macroscopic) organisms
Background image of page 8
This important information was discussed in lecture
Background image of page 9

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

View Full DocumentRight Arrow Icon
Evolution of size (length) increase in organisms at different periods of life on Earth… threshold Ten times larger
Background image of page 10
Animals tended to become larger and larger… WHY? Why does large size goes hand in hand with multicellularity? Why are size and multicellularity correlated?
Background image of page 11

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

View Full DocumentRight Arrow Icon
Relatively large size Buffers organism (unicellular or multicellular) against environmental fluctuations Greater protection against predators, enhances offensive tactics Longer life-spans More efficient use of metabolic energy CELLS that tended to become larger and with some specialization of structures for particular functions: flagella, cilia, photoreceptors etc. ADVANTAGES
Background image of page 12
Net costs of running for mammals of various sizes. The cost (in terms of rates of Oxygen consumption) decrease with increasing body size.
Background image of page 13

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

View Full DocumentRight Arrow Icon
Amoeba is a unicellular microscopic organism of the kingdom Protista…
Background image of page 14
If these advantages are so important, why then don’t we see a unicellular organism the size of an elephant?
Background image of page 15

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

View Full DocumentRight Arrow Icon
Why instead do we see Macroscopic organisms that are composed of many microscopic cells?
Background image of page 16
Surface area to Volume ratio
Background image of page 17

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

View Full DocumentRight Arrow Icon
explains why cells are so small
Background image of page 18
Image of page 19
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/13/2008 for the course BIO U103 taught by Professor Rosengaus during the Spring '08 term at Northeastern.

Page1 / 70

- The animal kingdom probably evolved from a colonial flagellated protist This ancestor was most likely a that lived over 700 million years ago in

This preview shows document pages 1 - 19. Sign up to view the full document.

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