ACTIVITY: Structure to Function: Hungry Reef Fish

NGSS Disciplinary Core Ideas
The activity below draws from the content in the page Structure to Function.


Image caption

Fig. 1. What might this fish eat with these large teeth?

Image copyright and source

Image courtesy of Dmitry Abramov


Fishes with different mouth shapes eat different types of food.


How does mouth shape and structure help a fish eat its food?

Guiding Questions:

  1. How do the different fish mouth structures help it function to eat?


Channel your inner fish! Use tools to model the structures of fishes' mouths—and then try to capture your prey!

Fish versus fishes: 

The word fish refers to one fish or to a group of fish of the same species. The word fishes refers to multiple species of fish. For example, 1 convict tang is a fish, 2 convict tangs are fish, and a group of 20 convict tangs are also fish. However, a convict tang together with a moray eel would be fishes.



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Fig. 2. Example materials for the ʻCruncher Station.ʻ 

Image copyright and source

Image by Emily Sesno

Station 1: The Cruncher (Fig. 2)

  • Hard cookies (i.e. Nilla Wafers)
    Healthy option: apples
  • Chopsticks
  • Tongs
  • Spoons
  • Blunt-tip pliers


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Fig. 3. An example ʻPickerʻ station.

Image copyright and source

Image by Emily Sesno

Station 2: The Picker

  • Egg carton (pre-cut dime size holes in each cup bottom and in between some cups)
  • Gummy Worms
    Healthy option: snap-pea crisps or string beans 
  • Needle-nose pliers
  • Blunt-tip pliers
  • Large tongs
  • Popsicle sticks
  • Toothpicks


Image caption

Fig. 4. Possible station set up for the ʻPoint-of-Viewers.ʻ

Image copyright and source

Image by Emily Sesno

Station 3: The Point-of-Viewers

  • Oreos
    Healthy option: apple slice sandwhiches with nut butter
  • Large gummy rings (i.e. Peach O-Rings)
    Healthy option: dehydrated apple rings
  • Paper Towels
  • String or yarn

Station 4: The Sucker

  • Tub of water
  • Raisins
  • Large spoon
  • Pippette
  • Bulb sucker (from ear cleaning kit or baby nose kit)
  • Turkey baster
  • Eye dropper


  1. Set up the feeding stations according to the materials list above.
  2. Read the station cards and instruction sheet.
  3. Practice 'feeding' using the tools and food items at each station.
  4. Record your observations on your worksheet.

Activity Questions:

  1. What are the mouth features of each type of fish (cruncher, picker, Point-of-viewer, sucker)?
  2. What kind of food do each of these fish eat (cruncher, picker, Point-of-viewer, sucker)?
  3. How do the structure of the fishes' mouth features function to help them eat their specific foods?
  4. How did your investigation help you understand more aobut how the different fishes eat?
  5. (Optional) Look through your fish ID guide and find another example of each type of fish based on the structure of their mouth and what they eat (cruncher, picker, Point-of-viewer, sucker).

Further Investigation

Complete the activity sheet to create a guide to different types of fishes and their eating behaviors!

Teacher Tip:

To reduce workload, assign individuals or groups to research some of the fish and then combine research to create a class guide.




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Exploring Our Fluid Earth, a product of the Curriculum Research & Development Group (CRDG), College of Education. University of Hawai?i, 2011. This document may be freely reproduced and distributed for non-profit educational purposes.