This document discusses the key characteristics and evolutionary history of animals. It outlines that animals are eukaryotic, multicellular organisms that rely on other organisms for food and lack cell walls. The document then describes the major eras in Earth's history when major animal diversification occurred, from the Cambrian explosion to the rise of mammals. It also defines important anatomical concepts like symmetry, tissues, body cavities, and phylogeny.

1. Hannah Love
12/01/2011
p. 654

2.  Animals are heterotrophs
 Heterotrophs: relies on other organisms for food
(as opposed to autotrophs)

3.  Eukaryotes: Organisms that carry genetic
material (DNA) in the form of chromosomes
within a distinct nucleus
 Multicellular: Made of multiple cells
 Animal cells have no cell walls
 Held together by structural proteins (like collagen)
 Muscle and nerve cells are unique to animals

4.  Cleavage: a succession of mitotic cell divisions

5.  Most animals reproduce sexually
 Some animals develop directly into adults
through transient stages of maturation
 Like humans
 Metamorphosis: Developmental transition
that turns the animal into a juvenile
 Juvenile: resembles an adult, but not entirely
sexually mature

6.  Neoproterozoic Era
 1 Billion – 542 Million Years Ago
 Ediacaran biota: Early eukaryotic bacteria
 Paleozoic era
 542-251 Million Years Ago
 Cambrian Explosion: dramatic explosion in the
growth of animal diversity (535-525 million years
ago)

7.  Mesozoic era
 251-65.5 Million Years Ago
 Animals began to spread into new habitats
 First dinosaurs and mammals
 Cenozoic era
 65.5 Million Years Ago – Present
 Began with mass extinctions
 Mammals rise

8.  Radial Symmetry: has
no left and right side,
any “imaginary slice”
creates mirror images
 Bilateral Symmetry:
only one “imaginary
slice” can divide this
into two mirror image
sides – right and left

9.  Tissues: integrated
group of cells with a
common function
 Maintain organization
within the animal’s
body

10.  Body cavity: fluid- or air-filled space

12.  Phylogeny: history
of organism lineages
as they change
through time
 New views of animal
phylogeny are
emerging from
molecular data