A Little Bit More
Whirligig Beetles are really interesting animals. You’ve probably seen small groups of them swimming over the surface of a small stream or body of water. Be sure you look closely at the illustration and notice that its 6 legs are not all the same. The front pair is quite different from the back 2 pairs. The front legs are adapted for grasping food while the back do the chore of moving the beetle through the water.
The air/water interface of the beetle’s bubble acts as a kind of membrane or gill through which oxygen can enter and carbon dioxide can leave. Unlike scuba equipment, which has a predetermined amount of air available to the diver, the insect can obtain several times as much oxygen from its bubble as it originally contained, due to the constant exchange of gases from the surrounding water. Oxygen diffuses into the bubble while carbon dioxide, expelled by the beetle, never accumulates in the bubble, since it is highly soluble in water and quickly migrates out. Nitrogen, which makes up about 80% of our air (80% of the insect’s original bubble), slowly diffuses out of the bubble into the surrounding water causing the bubble to decrease in size and usefulness over time. Once the bubble is too small, the beetle simply returns to the surface to acquire another.
Many aquatic adult beetles carry a thin film of air somewhere on their body surface, either under their wings or on the underside of their body, trapped by many tiny “hairs”. This trapped air is used both as an underwater breathing device, and as a help in floating at a specific depth without rising or sinking, much the way a fish’s swim bladder works to help it remain suspended at a specific depth. Jacques Cousteau never had it so good!
Activities
Acronyms
Objectives: Learn about acronyms
Materials: Assorted reference materials
Our language is full of acronyms. This exercise is an opportunity for students to see how common acronyms are in our culture. Your students may have trouble coming up with some since acronyms become so much a part of our everyday vocabulary we don’t even realize what they are. As you may already be aware, email has spawned lots of acronyms.
Here are a few acronyms if you want to provide some examples for your students:
· SCUBA – Self-Contained Underwater Breathing Apparatus
· POSH- Port Out, Starboard Home (Americans sailing to Europe used this term)
· ASAP – As soon as possible
· AWOL (a-wall) – Absent WithOut Leave (military term)
· NASA – National Aeronautics and Space Administration
· ROTC (rot-cee)- Reserve Officers Training Corps
· ZIP- Zoning Improvement Plan
· SONAR – SOund NAvigation Ranging
· RADAR – RAdio Detecting And Ranging
· LASER - (Light Amplification by Stimulated Emission of Radiation)
· RAM - (Random Access Memory)
· ROM - (Read-Only Memory)
You can provide your students with these acronyms or go on line (see web link) for more and see if they can find their definitions or have them bring in some to share with other students (this would be good to have family members involved too).
Key Concepts
Structures and Functions, Adaptations and Diversity
Questions
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