Unit/Task Title:Rocky Intertidal Field Trip Grade Level:5-8 Course(s):Science Author:Dan O'Grady
Content Area(s) addressed in this unit/task:
Science and Technology
Content Standards and Performance Indications.
These standards refer to the Maine Learning Results:

S+T: A3, B2, B3, B4, D3, G5
Guiding Principles taught and assessed in this unit:
Integrative and Informed Thinker
Assessment criteria (how will you know when they know):
Students could journal about their findings in the intertidal zone, draw creatures they discovered or diagram the sub-zones in the intertidal zone, indicating the creatures that occupy each zone.
Lesson Description:
Start by explaining the tides. The tide is a very important physical factor in the intertidal zone, because it controls what areas are submerged during certain times of the day. To explain the tides ask for three volunteers from the group, to be the earth, sun, and moon. The earth will wear a blue poncho to represent the oceans, and the sun and moon can wear cardboard cutouts around their necks. Show the students the relationships between the three bodies during the different parts of the lunar cycle, and how this affects the tides.

Next explain the zonation that occurs in the intertidal zone. The amount of time that different areas of the intertidal zone are submerged by seawater determines what types of organisms can live there. Because they are exposed to both water and air, only organisms adapted to deal with both sets of conditions can survive in the intertidal zone. Physical factors that organisms in the intertidal zone face include:

  • Temperature: Hot air in summer, freezing conditions in winter
  • Desiccation: Loss of water from tissues due to heat
  • Salinity: In tidepools, evaporation increases salinity, rain decreases it.
  • Oxygen: Organisms could use up the oxygen in the water of their pool if out the tide is out long enough.
  • pH: Some seaweed (Desmerestia) has a low pH and can reduce the pH of a tide pool
  • Wave action: Surf can roll small rocks and knock organisms off large rocks and ledge.

When examining any organism with the students, if possible point out how they are specially adapted to deal with the conditions faced in the intertidal zone.

The intertidal zone is a narrow habitat, because of this there is intense competition for space. Almost all of the available space in the rocky intertidal zone is occupied by some type of organism. Some organisms even live on top of others (epiphytes such as bryozoans, encrusting and coralline algae). Seaweed provides cover and traps moisture for many different organisms while the tide is out.

Juvenile lobsters live in the lowest part of the intertidal zone. These areas are only exposed during the lowest tides of the month (Spring tides). Since lobsters are not adapted to the air exposure, they can generally be found in pools under rocks while the tide is out. The Lobster Conservancy runs a juvenile lobster monitoring program, and our scientists and volunteers go to a specific sites along the Gulf of Maine coast to count larval lobsters.

The most important part of the lesson is allowing the students to explore the area themselves. Allow them to lift up clumps of seaweed, turn over rocks, and examine tidepools. It is important to remind them to replace animals and rocks exactly as they found them, and not to remove animals that are fixed in place. Have the students look in guide-books so they can learn how to identify the different organisms they find, and be able to do it on their own in the future. This activity will hopefully foster a sense of wonder and curiosity in them. Exploring the intertidal zone and finding new and unusual organisms can be a truly rewarding experience.

Other evidence to be collected that will insure understanding:
Journal entries
Drawings or diagrams
Feedback given to students:
Personalized written comments
What are the essential questions?
Opportunities for integrated technology - web resources:
What will insure understanding?
Time neeeded to complete unit:
1-2 hours on site
Resources needed:
Cooler, ice packs, containers to hold animals, guidebooks, boots, gloves, whistle, dissecting microscope, sun and moon symbols, blue poncho for tide demonstration
" Life Between the Tides: Marine Plants and Animals of the Northeast" is an excellent intertidal guidebook. For purchase information go to the Sea Grant website and click on publications.
Downloadable materials:
The shoreline etiquette download requires Adobe's free Acrobat Reader software in order to view the file. Most current computers have this software installed but if you find you need it just click below and download it.

Shoreline Etiquette (44K)

Copyright 2005 The Lobster Conservancy