NY Harbor Populations Investigation



Class Periods




Subject Areas



In this activity, students make predications about what the invertebrates in their small tank will eat.


  • Discern what invertebrate characteristics lend themselves to being a predator and/or prey.
  • Draw a food web that shows an accurate flow of energy through the web.

Materials and Resources


For each group:
  • a set of small invertebrates in a small tank with an aerator
  • several Petri dishes
  • white paper (taped to desk so animals in petri dish can be seen more easily)
  • tweezers
  • pipettes
  • hand lenses
  • sieves or screens

Instruction Plan


  1. Note: the next activity is a rich source of student questions about small arthropods.  Be sure to record your students’ questions and add them to your running list.  You’ll need that list for the students to propose large-scale studies in the upcoming lesson, Propose a NY Harbor population study.
  2. Each group gets their same small tank of invertebrates and their supplies.
  3. Groups revisit the observations and sorting of the invertebrates they completed in the previous lessons, Observe Small Invertebrates and Sort Small Invertebrates
  4. Students may want to remove the invertebrates from the tank and place in petri dishes on top of white paper in order to get a better look at certain body parts such as legs, claws, mouths or mandibles.
  5. Groups make predictions about which animals will eat what.  They start from the organisms at their table, and then rotate around the room in order to consider all the invertebrates in the classroom.
  6. Groups return to their original table and draw their own food web diagram.  
  7. Remind students: the arrows of the food web need to represent the flow of energy and point "up" the food web toward the consumers.
  8. Students compare their food web predictions with the Species ID and Food Web Cards. Would they make any alterations to their food web diagram?
  9. Students then, describe a way to figure out who eats whom by manipulating the animals they have in the classroom.