Amphipod Ecology

Amphipod Ecology is a lesson plan created by 2000 HOST Teacher Michael Collins

Objective

Students will count amphipods from the sand under kelp wracks that have been on the beach for different periods of time.   This will help students discover how long it takes the amphipods to find their food and the time when they start leaving for a better food source.  The students will age the kelp wracks from 1 to 5. This activity was developed to serve several purposes. The first was to teach the ecology and food chain hierarchy at the surf zone, so that the children are familiar with the different organisms that make up surf zone habitat and the competition for food from the ocean. The second purpose was to practice data collection and representation.   Students will learn to draw conclusions from data collection.Grade Level:  7-10

Introduction

The surf zone at the Coal Oil Point Reserve is a barren place.  There is no primary productivity going on in this area.  That means that all the food for the organism that live there must come from the ocean itself.   It must wash up on the beach and that is exactly what does happen.  Kelp wracks (sea weeds) are washed up on the beach, and many organisms eat the kelp.   “Beach hoppers” are one of the animals that depend on this food source.   Beach hoppers are amphipods and are a very important part of the food chain.   Thousands of birds feed on these every day, and many of these birds are endangered species.  Therefore, amphipods are an important part of the reserve ecology.Amphipoda is a large order of very small crustaceans also known as “beach fleas” or “sand fleas”.  The amphipod species found at the reserve, Orchestoidea corniculata, ranges from 1/2 to 1 inch long.  The second antennae is orange-red in color.  They have a compressed body shape and are most active at night.  They hide under kelp wracks, which they eat, and bury themselves in the sand.Amphipods need to find their food as soon as they can after it is washed up on the beach.  How long does that take?  When do they leave their food source and why?  This experiment tries to answer some of those questions. 

Location

Coal Oil Point Reserve Coal Oil Point Reserve

TIME REQUIRED: The Amphipod experiment could be completed successfully in as little as 45 -60 minutes. It could also be extended to allow time to identify the two different species in the area. Allow another class period for plotting and discussing results.

Teacher Preparation

Before the trip, spend some class time talking about ecology and other concepts such as food chains and competition.  The expected results are that when students plot the number of amphipods on the y-axis and the age of the kelp from 1 to 5 on x-axis, there will be a bell-shaped curve.  This should indicate that most of the amphipods are located at the medium-aged kelp wrack.

Procedure

Students will age the kelp wracks from 1 to 5

  • 1 = fresh, recently washed ashore
  • 2 = wilted
  • 3 = beginning to dry
  • 4 = moderately dry
  • 5 = completely dried out (with very few amphipods living there)

Students use a standard sample size such as one shovel full of sand.

Students count amphipods in the sand and record the data. 

PLACE EACH SAND SAMPLE BACK WHERE IT WAS COLLECTED.  DO NOT REMOVE THE ORGANISMS OR THE SAND FROM THE RESERVE.

Divide the students into groups of three.  So that the amphipods are not counted twice, each group will have a student performing the role of counter, recorder, or collector.

Students plot data on a graph and discuss the results.

Possible Extensions:  There are two different types of amphipods on the beach.  See if students can tell the difference by the way they pile the sand.   One species piles sand in a line in one direction, while another piles sand all over in a circle. 

Evaluation

  • Students will present their plotted results.
  • Ask the students how long they think it takes amphipods to find their food.
  • Ask the students when the amphipods leave their food source and why.
  • Ask students to explain why amphipods are important to the surf zone ecology.

Teacher Materials

  • papergraph
  • paperpencils 
  • shovel
  • container to hold sand