CH_22_STUDENT_OUTLINE

CH_22_STUDENT_OUTLINE - Chapter 22: Animal Diversity I,...

Info iconThis preview shows pages 1–15. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 22: Animal Diversity I, Invertebrates
Background image of page 1

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

View Full DocumentRight Arrow Icon
Key Features of Animals Animals possess all of the following characteristics: Multicellularity Heterotrophic Cells lack a cell wall Are able to respond rapidly to external stimuli Most animals populating the Earth were present by the Cambrian period (544 million years ago) extant – opposite of extinct
Background image of page 2
Animal Evolution Certain features represent evolutionary milestones: The appearance of tissues The appearance of body symmetry Protostome and deuterostome development (development during pregnancy) These features mark major branching points on the animal evolutionary tree
Background image of page 3

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

View Full DocumentRight Arrow Icon
Porifera (sponges) Cnidaria (jellyfish, corals, anemones) Ctenophora (comb jellies) Arthropoda (insects, arachnids, crustaceans) Platyhelminthes (flatworms) Annelida (segmented worms) Mollusca (clams, snails, octopods) Echinodermata (sea stars, sea urchins) Chordata (lancelets, vertebrates) cuticle molted protostome development deuterostome development bilateral symmetry radial symmetry no tissues tissues Nematoda (roundworms) 0 PRIMITIVE ANCESTOR
Background image of page 4
The Appearance of Tissues Tissues are groups of similar cells that carry out a specific function (i.e. muscle) The earliest animals had no tissues Sponges are the only modern-day animals that lack tissues Individual cells may be specialized, but they act independently Sponges and other phyla arose from an ancient common ancestor without tissues 3 types of layers…
Background image of page 5

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

View Full DocumentRight Arrow Icon
Animal Tissues Ectoderm (top) Endoderm (bottom) Mesoderm (middle)
Background image of page 6
The Appearance of Body Symmetry Symmetrical animals have an upper (dorsal) surface and a lower (ventral) surface Animals with tissues exhibit either radial or bilateral symmetry 3 types Radial, bilateral, asymmetric (no symmetry) Bilateral – most advanced; asymmetrical – least advanced
Background image of page 7

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

View Full DocumentRight Arrow Icon
Radial Symmetry Can be divided into roughly equal halves by any plane that passes through the central axis (mirror image) Have two embryonic tissue (germ) layers: Ectoderm (outer layer, covers the body) Endoderm (inner layer, lines most hollow organs) Tend to be either sessile (fixed to one spot) or “free floating”, drift around on currents Cnidarians (jellyfish), hydra
Background image of page 8
Radial symmetry central axis plane of symmetry
Background image of page 9

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

View Full DocumentRight Arrow Icon
radial symmetry
Background image of page 10
Bilateral Symmetry Can be divided into mirror-image halves only along one plane that runs down the midline Have an additional germ layer: Mesoderm (middle layer, forms muscle & circulatory/skeletal system) Exhibit cephalization (concentration of sensory organs & brain in a well-defined head) Defined anterior (head) and posterior (tail) regions
Background image of page 11

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

View Full DocumentRight Arrow Icon
Bilateral symmetry anterior plane of symmetry posterior
Background image of page 12
dorsal anterior posterior ventral bilateral symmetry
Background image of page 13

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

View Full DocumentRight Arrow Icon
Body Cavities Most bilateral animals have a body cavity Serve many functions Skeleton: provides support and a framework against which muscles can act
Background image of page 14
Image of page 15
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 65

CH_22_STUDENT_OUTLINE - Chapter 22: Animal Diversity I,...

This preview shows document pages 1 - 15. Sign up to view the full document.

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