Download Classifying animals

Pages 96-102
 Multicellular
eukaryotes lacking cell walls
 Heterotrophic,
 Most
 All
obligate aerobes
are motile
have a hollow cavity surrounded by
multiple layers (2 or more) of cells at some
stage of development
 Further

Presence or absence of nerve cells


dividing animals:
Used to sense environment and coordinate movement
Symmetry


Radial: body arranged around a central point like the
spokes of a wheel
Bilateral: body has sides that are mirror images of
each other
 Further

Order of embryonic development



dividing animals:
Protosome: mouth forms before the anus
Deuterostome: anus forms before the mouth
Presence or absence of backbone/notochord


Vertebrate
Invertebrate
 Further

dividing animals:
Number of germ layers




Germ layers: layers of cells in developing embryo that
give rise to specialized tissues
Ectoderm: Outer layer that gives rise to skin, nerves,
hair, shells, scales
Mesoderm: Middle layer that gives rise to circulatory,
reproductive, excretory, and muscular systems
Endoderm: Inner layer giving rise to inner lining of gut
and respiratory system
 Further

dividing animals:
Presence or absence of coelom

Coelom: body cavity that contains internal organs