A CIESE Realtime Data Project

Survival Zone - Teacher Guide: Lesson Plans

Survival Zone

Why is the Intertidal Zone such a dangerous place to live?

Students will be able to:

  • determine where the high and low tides will reach on a particular shoreline
  • determine which organisms can live in the Intertidal Zone
  • determine which organisms could be collected for food

computers with Internet access
Student Worksheet (.doc)
optional: web publishing software

The Intertidal Zone is the area of the shoreline located between the high tide and low tide areas. The intertidal zone is separated into three major zones and can usually be determined by the organisms found within:

  • Lower intertidal - This zone is dry only during the lowest tides and contains the highest biodiversity including organisms such as; sea stars, algae, crustaceans.
  • Middle intertidal - This zone is regularly covered with sea water and contains organisms such as algae, crustaceans.
  • Upper intertidal - This zone is covered by water during high tide so it experiences dry periods daily. Organisms dwelling in this zone must either be mobile or have the ability to somehow stay moist between tides.

Sometimes considered the fourth zone, the Spray zone, is the "desert" of the intertidal zone. Only organisms capable of surviving on the spray of water created by crashing waves dwell in this zone.

Life if the Intertidal Zone is difficult. Several organisms have developed special adaptations to prevent against:

  • Overheating/Drying
  • Freezing
  • Pounding water
  • Salinity changes
  • Predation

The following links provide more background information about the Intertidal Zone as well as localized examples:

Olympic Intertidal Zone
Maine InterTidal Zone Investigation

1. Determine the Water Level Tidal Predictions for Portland, ME for the next month.
Does this area experience semi-diurnal, diurnal, or mixed tides?

2. Determine the current status of the area. Portland, ME
Is there evidence of major deviations in predicted and actual water levels for Portland?

3. Obtain the Weather for Portland, ME.
Will there be any extreme weather for Portland in the upcoming week?
Would the Intertidal area be subjected to freezing weather in the upcoming week?

4. Read all of the information on the various organisms. Determine if they would survive in the Intertidal Zone and if so, in which part, the Lower, Middle or Upper portion. Explain your reasoning.

Sea Star
Sea Lettuce
Red Mangrove

5. Which of the organisms would be considered edible for humans?

1. Produce a Field Guide, either paper-based or electronic of organisms found at your local shoreline.

The Field Guides must address the following:

  • Type of tides in the area, semi-diurnal, diurnal or mixed
  • Prediction of any higher than normal high tides or lower than normal low tides
  • Local effect of weather on the Intertidal Zone
  • At least three organisms for each portion of the Intertidal Zone
  • Name of organism
  • Type of organism (classification)
  • Picture of organism
  • Where it lives in the Intertidal Zone
  • What form(s) of adaptation does it display to survive in this zone?

The following links may be helpful in the creation of the Field Guides:

Water Level Tidal Predictions
Water Level Observation Network