## Giant Squid Jets

life sciences,
physical sciences,
art

3-8

one class period

You may print this activity
for educational use.

### Objective

Before their visit, students will learn how ... jet propulsion works by making a biomechanical model.

#### Background Information

Imagine you're sitting on a chair that has wheels, and you're facing a wall. If you lift your feet and push against the wall, the wall exerts a force that pushes you backward. Push softly and you'll roll back a short distance slowly. Push harder, you'll jet backward faster and farther. This illustrates Newton's Third Law of Motion: for every action there is an equal and opposite reaction.

Giant squids and balloons put Newton's Third Law of Motion to use. When a balloon is blown up, the air inside pushes on the rubber, and the rubber pushes back. As long as the balloon is closed tight, nothing happens. But if you let air out of the balloon, the rubber pushes on the air inside and the air rushes out. When it does, the force of the escaping air pushes the balloon in the opposite direction.

A giant squid's body is like a balloon. Its outer skin is like the rubber of a balloon. Between the outer skin (called the mantle) and its organs is a space, called the mantle cavity. One end of the space opens and closes like a gate; at the other is a funnel, similar to the open end of a balloon. A giant squid pumps water through the gate, closes the gate, then squeezes the water out of the funnel. Like the balloon, the escaping water pushes the giant squid forward in the opposite direction, and the g iant squid jets away.

This activity gives your students a closer look at how a giant squid uses jet propulsion to swim.

### Activity

#### Materials

• A balloon.
• A paper clip or twist tie.

Also:

• Tape.
• Streamers.
• Markers.

### QUESTIONS TO BEGIN

What parts of your body do you use to move across the room?

If the room was filled with water, would you move the same way as you do when you walk? Why or why not?

### Procedure

1. Show students a video or pictures of giant squid swimming through the water.
2. Give each student a balloon for making a giant squid.
3. Have students use markers to add eyes to their giant squid balloons (the giant squid's eyes and head are near the opening of the balloon).
4. Have students blow up a balloon fully and close securely with a twist tie.
5. While balloon is still inflated have students attach streamers (for giant squid arms and tentacles) with tape near the tied end of the balloon.
6. When all the giant squids are complete, have students, one at a time, demonstrate giant squid jet propulsion by removing the twist ties and watching the giant squid shoot through the air.

### QUESTIONS TO CLOSE

What do the models show us about how a giant squid moves?

Do you think real giant squids use air to swim or something else?

What do you think they use to power their jets in the water?