The World of Animals. I. Life evolved in the oceans A. Least stressful environment B. Moderating temperature C. Closest to osmotic properties D. Buoyancy.

The World of Animals

I. Life evolved in the oceans

• A. Least stressful environment

• B. Moderating temperature• C. Closest to osmotic

properties• D. Buoyancy not a problem• E. Gametes can be released

with no problem• F. Abundant food

II. Parazoa-Sponges (Porifera)A. Introduction

• 1. do not possess true tissues• 2. cell layers are loose associations• 3. if you take a sponge and pass it through a screen-it can reassemble• 4. layers are dependent upon one another-but not as dependent as

higher levels• 5. very sessile organisms• 6. lack muscles, nerves-individual cells can react to the environment

B. Body Plan• 1. epidermis with porocytes• 2. mesohyl with amoebocytes• 3. Inner cell layer with choanocytes

4. Endoskeleton of spicules

• a. some spicules are calcium carbonate

• b. some spicules are proteinaceous

• c. found in mesohyl• d. can be used to

classify sponge

5. Choanocytes power the sponge

• a. 275 gallons needed to produce three ounces of new sponge

• b. Flagella creates water currents

• c. Microvilli filter water as it comes through

6. Osculum and spongocoel

C. Reproduction of sponge

• 1. asexual fragmentation• 2. production of gemmules• 3. sexual reproduction-

hermaphroditic

III. Cnidarians or Coelenterates

A. Basic body plan

• 1. diploblastic• 2. gastrovascular

cavity• 3. radial symmetry• 4. tentacles• 5. cnidoblasts• 6. mesoglea• 7. two basic forms-

polyp and medusa

Polyp or medusa?

B. Cnidocyte

C. Classes• 1. Hydrozoa– a. Alternate– B. Poly most predominant

Examples of hydrozoans

Hydrozoans

Hydra videos

• http://www.schooltube.com/video/8b4ca7db15144b83b7c6/Hydra

2. Scyphozoa• a. Medusa stage is prevalent• b. jellyfish

3. Anthozoa-sea anemones and corals

Other anthzoans