Title: Adaptations In A Salt marsh

Discipline: Life Science

Ability Level: 7^th Grade

Time:

NJ Core Curriculum Content Standards:

5.1, 5.5, 5.8, 5.9

Objectives:

Students will learn about the different organisms that live in a salt marsh. They will also learn how the organisms adapt to high salinity and daily tidal inundation, which create stressful conditions in the marsh. This activity stresses communication between the students. The activity is designed so that the students learn from each other.

Materials:

Salt marsh zone handouts

Student handout

Organism Cards

Hats or some item to indicate who are the zone managers

Background:

Salt marshes occur anywhere the ocean meets the land. These marshes are subjected to flooding twice a day caused by the tide. The organisms that live in the salt marsh have special adaptations that allow them to control their salt intake and tolerate being inundated by water twice a day. The zonation that occurs in the salt marsh is caused by the tide rising on the land surface( see salt marsh cross-section). The sudtidal zone in lowest part of the salt marsh and there is always seawater there. Plants and animals that live there need to be adapted to high concentrations of salt and being under water all the time. The low marsh in inundated by water for many hours therefore organisms the live here must be adapted to this long period of inundation. The high marsh in under water for a short time. Organisms that live here do not like to be in the water.

Pre-discussion:

The teacher should discuss what a salt marsh is and the environmental conditions that exist there. Discuss the tide and salt marsh zonation. Show the students the cross-section of the salt marsh and where the zones are located. Discuss what an adaptation is and give different examples.

Activity:

3 students are named as zone managers. Each of these students receives a description of their zone and the animals and plants that can live successfully in the zone (see handouts). The rest of the students are given a card with a picture and description of an organism that lives in the salt marsh. Based on the description students must complete questions 1 and 2 of the handout. They should be able to figure out how long their organism can tolerate being under water, as well as the food that they eat. Once they know this information they must go and interview the zone managers to find out how long that zone is under water and whether the food they need to eat also exists in that zone. The zone manager must not tell the student directly if they are in that zone. Students must figure this out for themselves based on their answers to questions 1 and 2 and the response of the zone manager to their questions.

Once the student finds their zone they stay with that zone and complete the rest of the handout.

This activity allows the students to walk around the room and learn from each other. Once they are in their groups they continue to discuss the adaptations of their organisms and what they have in common.

Evaluation:

Each zone or group should give a short presentation on the conditions that exist in that zone as well what all the organisms have in common that live there. The teachers should ask questions about specialists (organisms that are restricted to the salt marsh habitat). For example, cord grass has special salt glands on their stem to excrete excess salt. Osprey has salt glands by their eyes, which help them get rid of excess salt. Fiddler crabs burrow into the mud when the tide comes in to avoid drowning. These are important adaptations to point out, especially to the students who did not have these organisms in their zone.

Extensions:

• Each group can create a food chain based on the organisms in their zone and the teacher can discuss the difference between producers and consumers.
• Osmosis- most of the animals have to figure out how to reverse osmosis under these high salinity conditions. For advanced classes, this lesson is a good way to show how organisms osmoregulate (control the amount of salt in their bodies).
• Competition between organisms for resources- this can be done by giving 2 students the same organism, and then creating 2 of each. Each zone can only have one organism. If done this way, concepts such as competition between organisms for space and food can be discussed.

Self-Assessment/ Reflection:

7th grade life science classes and 8th grade physical science classes did the activity. This activity was developed to introduce the students to what they would be seeing the following week when they visited a real salt marsh. At the marsh all the students had the hands-on experience of using a seining net to explore the aquatic organisms in the salt marsh. The pre-lesson seemed to give them a good introduction to the marsh environment. Students were pointing out and discussing organisms we had spoken about the week before in the classroom.

When we did the activity with 2 classes at once (50 students) it did go as smoothly as one class. The activity should be done with classes no larger than 30 students in a 45-minute period. If there is more time available, then the activity can be done with larger groups and the competition extension should be incorporated.