Billion Oyster Project

Sort Small Invertebrates


NY Harbor Populations Investigation



Class Periods




Subject Areas



In this activity, students sort their invertebrates into difference categories based on close observations.


  • Make close observations
  • Develop a categorization system
  • Modify their system based on feedback and effectiveness

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

Before you get started

Tips for Teachers

  • Remind students to transfer the organisms extremely gently!

Instruction Plan


  1. Note: This 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 with invertebrates and their supplies.
  3. Each group also has access to...
    • extra brackish water
    • a sieve or screen
    • BOP Species ID Cards and Food Web Cards (they are not required to use them at this time, but as they raise relevant questions, consider directing them toward these resources)
  4. Students closely observe their invertebrates and look for similarities and differences.  Once the students in a group have had a chance to discuss their observations, they need to decide how they are going to sort their invertebrates into groups (e.g. based on color, body parts, size, etc).
  5. Encourage students to break up their arthropods into more than one group so they're not just lumping all the smallest organisms together without looking at them closely.
  6. Students sort their invertebrates into groups and record their categorization system and how many invertebrates were in each category.
  7. Students gently place invertebrates back together in one tank.
  8. Once all groups are finished, students swap tables (and invertebrates .  Groups now use each other’s catagorization systems to sort and count each other’s invertebrates. The visiting group records how many invertebrates they put into each category. 
  9. Original groups go back to their tables (and arth invertebrates ropods) and check how well the visiting group carried out their categorization system.  Did the sorting of the visiting group match their own sorting? Did the categorization system work well?  Is there a way in which groups need to change or improve their categorization system?  Groups record any changes on their handout.
  10. Groups report out about their categorization system.  As groups present they should point out similarities and differences between their system and other groups' systems.  Discuss which systems worked well and why.
  11. Students put animals into an aerated tank for safekeeping.