Chapter 32: An Introduction to Animal Diversity

Hannah Love12/01/2011p. 654

Nutritional Mode

Animals are heterotrophs Heterotrophs: relies on other

organisms for food (as opposed to autotrophs)

Cell Structure and Specialization 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

Reproduction and Development

Cleavage: a succession of mitotic cell divisions

Reproduction and Development 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

The History of Animals

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)

The History of Animals

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

Symmetry

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

Tissues

Tissues: integrated group of cells with a common function Maintain

organization within the animal’s body

Body Cavities

Body cavity: fluid- or air-filled space

Protostome and Deuterostome Development

Phylogeny and Molecular Data

Phylogeny: history of organism lineages as they change through time

New views of animal phylogeny are emerging from molecular data