What Is an Animal? Animal Symmetry Sponges and Cnidarians

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Table of Contents

• What Is an Animal?
• Animal Symmetry
• Sponges and Cnidarians
• Worms

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Structure of Animals
- What Is an Animal?

• The cells of most animals are organized into
  higher levels of structure, including tissues,
• organs, and systems.

3
Classification of Animals
- What Is an Animal?

• This branching tree shows how the major animal
  groupsare related.

4
Asking Questions
- What Is an Animal?

• Before you read, preview the red headings. In a
  graphic organizer like the one below, ask a what
  or how question for each heading. As you read,
  write answers to your questions.

Question
Answer
What is a cell?
A cell is the basic unit of structure and
function in living things.
The cells of animals are organized into tissues,
organs, and systems.
What is the structure of animals?
Animals must obtain food and oxygen, keep a
stable environment within their bodies,
reproduce, and move about to meet their needs.
What are the functions of animals?
Animals are classified according to how they are
related to other organisms.
How are animals classified?
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Links on the Animal Kingdom
- What Is an Animal?

• Click the SciLinks button for links on the animal
  kingdom.

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The Animal Kingdom
- What Is an Animal?

• Click the Video button to watch a movie aboutthe
  animal kingdom.

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Invertebrates
- What Is an Animal?

• Click the Video button to watch a movie about
  invertebrates.

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End of SectionWhat Is an Animal?
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Comparing and Contrasting
- Animal Symmetry

• As you read, compare and contrast the
  characteristics of animals with bilateral
  symmetry and radial symmetry in a Venn diagram
  like the one below. Write the similarities in the
  space where the circles overlap and the
  differences on the left and right sides.

Radial Symmetry
Bilateral Symmetry
One line of symmetry, halves that are mirror
images, front end with sense organs, quick
movement
Many lines of symmetry, no distinct front end,
live in water, move slowly
Balanced arrangement of parts, perform all the
basic life functions
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Links on Animal Symmetry
- Animal Symmetry

• Click the SciLinks button for links on animal
  symmetry.

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End of SectionAnimal Symmetry
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Sponges
- Sponges and Cnidarians

• Structures surrounding the central cavity of a
  sponge are adapted for different functions.

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Sponges
- Sponges and Cnidarians

• The sexual reproduction of sponges involves a
  larval stage that moves. Adult sponges stay in
  one place.

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Structure of a Sponge Activity
- Sponges and Cnidarians

• Click the Active Art button to open a browser
  window and access Active Art about the structure
  of a sponge.

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Calculating a Rate
- Sponges and Cnidarians

• To calculate the rate of water flow in a sponge,
  divide the volume of water that the sponge
  filters by the time it takes the water to pass
  through the sponge.
• Flow rate Volume of water/Time
• For example, a marble-sized sponge filters 15.6
  liters of water in a day. How many liters does it
  filter per hour?
• Practice Problem
• In four days, a sponge filters 1,200 L. What is
  its rate of water flow per day?

• 300 L/day

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Cnidarians
- Sponges and Cnidarians

• Cnidarians have two basic body plans, the
  vase-shaped polyp and the bowl-shaped medusa.

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Cnidarians
- Sponges and Cnidarians

• Cnidarians use stinging cells to capture food and
  defend themselves.

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Cnidarians
- Sponges and Cnidarians

• The life cycle of a moon jelly has both a polyp
  and a medusa stage.

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Comparing and Contrasting
- Sponges and Cnidarians

• As you read, compare and contrast sponges and
  cnidarians by completing a table like the one
  below.

Sponges
Cnidarians
Feature
Polyp or medusa, central body cavity, tentacles
Body structure
Hollow body with pores
Cell type that traps food
Collar cells
Stinging cells
Method(s) of reproduction
Sexual and asexual
Sexual and asexual
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End of SectionSponges and Cnidarians
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Characteristics of Worms
- Worms

• Biologists classify worms into three major
  phylaflatworms, roundworms, and segmented worms.

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Life Cycle of a Dog Tapeworm
- Worms

• This flatworm is a parasite that lives in more
  that one host during its life cycle.

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Roundworm Numbers
- Worms

• Biologists counted all the roundworms living in a
  plot of soil. Then they calculated the percentage
  that lives in different depths of soil.

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Roundworm Numbers
- Worms

• Reading Graphs
• Where in the soil was the largest percentage of
  roundworms found?

• In the first centimeter

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Roundworm Numbers
- Worms

• Calculating
• What is the total percentage of roundworms found
  in the first 3-cm depth of soil?

• About 87

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Roundworm Numbers
- Worms

• Drawing Conclusions
• What is the relationship between the depth of
  soil and the abundance of roundworms in the soil?

• The deeper the soil, the fewer the worms

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Segmented Worms
- Worms

• Earthworms and other segmented worms have bodies
  made up of many linked sections called segments.

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Using Prior Knowledge
- Worms

• Before you read, write what you know about worms
  in a graphic organizer like the one below. As you
  read, write what you learn.

What You Know

• Worms are long and skinny.
• Worms live in the ground and digest soil.
• Worms are slimy and wriggly.

What You Learned

• Worms have bilateral symmetry.
• Some worms are flat.
• Some worms live in water.
• Some worms are parasites.
• Worms have a nervous system.

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More on Worms
- Worms

• Click the PHSchool.com button for an activity
  about worms.

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End of SectionWorms
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Graphic Organizer
Sponge releases sperm.
Sperm enter another sponge and fertilize egg cell.
Larva settles on a surface and develops into
adult sponge.
The Life of a Sponge
Water currents carry away larva.
Larva develops.
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End of SectionGraphic Organizer