For each group of four students:
Optional: Cameras or camera phones for each group
Students who demonstrate understanding can:
If they finish their survey before the 15 minutes is up, invite them to add details to their drawing and make more observations about the zone in their Science Notebook. If cameras or camera phones are available, ask the chaperones to take a picture of the plot for use back in the classroom and keep track of which zone the photo was taken in.
Depending upon the low tide/high tide cycle, students should start either with the splash zone or with the lowest zone that will be exposed during the time you will be at the beach.
Students carry out their sampling and surveys in each of the four zones with the teacher or a chaperone keeping track of the track of time and making the signal to move to the next zone.
At the conclusion of the intertidal zone survey, bring the groups back together. Ask students in each group to share their findings with another group.
After they have talked with one another, ask: In what zone did you find the most mussels, the fewest anemones, the most fish? Which zone was underwater? Which zone was dry? Which zone had grasses? Seaweeds?
Ask students to brainstorm explanations for their results and observations. Did different zones have the same species or was there a different diversity of species in the four intertidal zones? Why do you think there was more or less diversity in some zones than in others? What challenges to survival did animals need to meet in each zone? (The class discussion will support those who may have had difficulty understanding the concept of diversity. Sharing observations will also help to teach those who may need more guidance.)
EXTENSIONS: (60 mins.) This activity (using plots, sketching, surveying) can be done in other habitats to find the diversity of life, such as those they walk through getting to the beach (forest, meadow) or in other types of habitats (streamside habitat, freshwater wetlands).
Back in the classroom give students a 12” x 18” inch piece of construction paper. As a review of the class discussion at the end of the field trip, ask students to describe the pattern they observed over the four zones in terms of “most” and “least” number of different types of seaweeds and animals on one side of the paper. Guide them to fold the paper long-way twice into four equal parts. On the other side of the paper, have them label the intertidal zones at the top of each of four columns. Give students the option to write about, draw or cut out line drawings of intertidal animals (See Resources section for links to line drawings.) and place them in their zones. If you have pictures of their study plots, allow them to look at the pictures as they fill in their columns.
You can also provide a bonus question that they can also answer on the back of their tide zone model:
Why do you think you would find many barnacles in the splash zone and no nudibranchs or sea stars?
Note to teacher: Additional tasks will be needed to fully assess student performance for the ELA, Math, and cultural standards.
|#res44||Life of the Beach: Among Friends and Anemones|
DVD with beach etiquette messages and an introduction and footage of animals typically found in different intertidal zones on Alaska’s rocky beaches.
|Laminated Field Guides|
|#res45||Field Guide for Intertidal Life of Southeast Alaska|
By Katherine Hocker. Discovery Southeast.
|#res46||Beachcomber's Guide to Intertidal Marine Invertebrates of Southcentral Alaska|
By Carmen and Conrad Field
|#res47||Seaweeds of Alaska|
Images can be downloaded from the Seaweeds of Alaska website and laminated.
|Line Drawings of marine invertebrates, seaweeds, and sea grasses|
|#res48||Line drawings of marine organisms|
Alaska Sea Grant Alaska Seas and Watersheds website
|#res40||Alaska Ocean ABCs|
By Conrad Field
|#res49||Where the Land and Sea Meet|
By Kirsten Carlson. Also includes coloring, connect-the-dot, and drawing activities for a variety of different types of seashore and includes illustrations and information on 92 species, including where they’ve been seen throughout the world.
|#res50||One Small Square: Seashore|
By Donald M. Silver (Also available for Arctic Tundra and Pond habitats)
|#res51||One Small Place by the Sea|
By Barbara Brenner
|#res11||Musty Crusty Animals||Book series by Lola M. Schaefer|
|Resources for Bilingual and Cultural Connections|
|#res9||Eék: Beach (Tlingit)||Grade Level K-1. Sealaska Heritage Institute. Includes study prints and cut outs of common beach animals. The lessons include one focused on a Tlingit legend, The Old Woman of the Tides, an introduction to intertidal zones, ones focused on marine animals representative of each tidal zone (barnacles and hermit crabs in the upper intertidal zone, sea anemones and sea urchins for the middle intertidal zone, sea stars and gumboot chitons for the lower intertidal zone). Lingit vocabulary and traditional uses of beach animals and their cultural significance are emphasized in all of the lessons, including color pictures of 10 animals with English group name (e.g., barnacle) and Lingit name along with sentences in Lingit using the animal names.|
The variety, or diversity, of life on Alaska beaches often is distributed in distinct bands, or zones, of biological communities that parallel the shoreline. Shoreline zonation is most distinct on rocky beaches, particularly on the faces of large boulders or bedrock outcrops where the plants and animals that are adapted to life on the rocky substrate also are adapted to different levels of exposure to the tides. Where the tidal range is large, the zones are spread out and can provide excellent opportunities for students to observe a diversity of seaweeds and animals in each zone. In places where the tidal range is smaller, the zones will be compressed. The presence of large boulders and the type of rock that forms tide pools provides other opportunities to observe diversity over small areas.
The communities on these rock habitats are very different from those adapted to live in soft-bottom substrates of sand or mud. Some beaches are mixtures of rock outcrops, boulders, cobbles, and areas where sand and mud are deposited. Beaches with this mixture of substrate types support the largest number of different species, and therefore the highest biodiversity. Although this activity was developed for rocky beaches where the zonation is distinct, the same approach can be used on other types of beaches with more than one type of substrate (e.g., boulders, large and small rocks, sand, and/or mud or to compare and contrast the diversity in different types of habitats.
In Alaska, the tidal cycle is semi-diurnal, with two cycles of high and low tides approximately every day. (Approximately, because the timing of the tides is a result of lunar cycle of the “tug” of the moon on the Earth, and the lunar day is slightly longer than 24 hours). In some locations in Alaska, tides have a large range between the highest high tides and the lowest low tides because the shape of inlets and channels “squeeze” the incoming water and cause it to pile up along the shoreline.
Who or What Lives Where, and Why
Alaskaʼs beaches are dynamic and often harsh environments for plants and animals. However, many species are uniquely adapted to live “between the tides.” This section of shoreline, which is the area uncovered by the lowest tides and covered by the highest tides, is known as the intertidal zone. The distribution of plants and animals in the intertidal zone appears to be dictated by a combination of biological adaptations to physical conditions and to inter- and intra-species competition and predation.
Upper limits for plants and sessile (fixed) animals are generally set by their tolerance to physical factors, while the lower limits are often set by biological interactions.
The intertidal zone is progressively more crowded at the lower tidal levels where complex dramas are played out in competition for space and food and the avoidance of becoming food. For mobile animals, behavior often provides important adaptations that influence where they can survive.
The most important factors that determine the suitability of the different tidal zones as habitat for each plant and animal species are tidal dynamics, exposure to waves, substrate type, and ecological interactions.
For more information about marine invertebrates commonly observed on Alaska beaches, see Meet the Invertebrates.
Splash Zone: The places on a beach exposed to occasional wave surges or spray of salt water often during storms. Seaweeds and animals found here have to be hardy to survive long periods out of the water, exposure to sun, and fresh water from rain. Diversity is the lowest of all the zones.
Upper Intertidal/High Tide Zone: Wet during high tides. This is the part of the beach exposed to air most of the time, covered only during the higher tides in the cycle. Few types of plants, seaweeds, or animals can survive being dry most of the time when the tide is out, being submerged in salt water occasionally, the risk of being washed away by waves, and exposure to temperature extremes often on a daily basis. Diversity is low.
Middle Intertidal/Mid-Tide Zone: Wet and dry. These are the places on a beach closest to “land” that is usually covered and uncovered twice a day by the tides and where exposure to air lasts longer during periods of higher and lower tides and for a shorter amount of time during more moderate tides. Diversity is higher than further up the beach but only of organisms that can survive life both underwater and out-of-water. The diversity includes more animal predators and their abundance can limit whether or not their prey can survive in this zone.
Lower Intertidal/Low Tide Zone: Usually wet.These are the places on a beach exposed to air only during the lowest tides. The highest diversity of both seaweeds and animals are in this zone because they only have to tolerate short exposures to air that don’t occur every day. Some animals become stranded as the tide recedes but others can move up the beach to find food. Predator-prey relationships affect survival in this zone as do other relationships between species, especially competition.
In the primary grades, the NGSS emphasize observations of patterns and a foundational understanding of relationships between the external structures and their functions for plants and animals. The emphasis is not on classification for the sake of grouping and naming. The NGSS specifically exclude assessment of knowledge of animal species names in primary grades, however, learning Alaska Native names of culturally-important animals and animal groups receives emphasis in bilingual education in a number of Alaska school districts. Teachers should use their judgment in terms of the emphasis placed on assessing learning about the scientific or common names of different species or species groups.
Prior Student Knowledge: Students will have had prior experience observing plants and animals in different tidal zones on Sea Week field trips although they may not recognize the different zones. They will know how to group animals based on shared external structures (mollusks, crustaceans, echinoderms, bivalves, univalves) and have been introduced to variation in traits between parents and their offspring (plants and animals) and among individuals of the same type of plant or animal.
Students should also have foundational conceptual understandings in cross-cutting concepts of patterns, structure and function, and systems.
Possible learner preconceptions, misconceptions and instructional clarifications:
Learner Preconception/misconception: Plants and animals can live anywhere on the beach.
Instructional Clarification: Survival, and thus the pattern of distribution of plants and animals on a beach is related to many factors, as described in the Teacher Background section. The concept of adaptation (that in any given habitat, some organisms can survive well, some can survive less well, and some cannot survive at all) is a 4th grade Life Science concept but students at this developmental stage can observe and collect data that will allow them to infer patterns that demonstrate that plants and animals cannot live anywhere on the beach.
Learner Preconception/misconception: Animals that live in tide pools or other places in the lower intertidal zone can survive out of the water.
Instructional Clarification: Many animals that live in tide pools spend their entire life in the same tide pool. Animals like tidepool sculpins that aren’t able to breathe air very long, so are somewhat restricted to pools. Other animals in the lower intertidal zone can spend a limited amount of time out of the water but need to stay wet to survive. If they move too far up the beach when the tide is out, they can dry out and die before the tide comes back in.
Planning and Carrying Out Investigations
Make observations (firsthand or from media) to collect data which can be used to make comparisons. (2-LS4-1)
Science Knowledge Is Based on Empirical Evidence
Scientists look for patterns and order when making observations about the world. (2-LS4-1)
LS4.D:Biodiversity and Humans
There are many different kinds of living things in any area, and they exist in different places on land and in water. (2-LS4-1)
None are listed for this NGSS performance expectation.
Cause and Effect is a relevant cross-cutting concept emphasized in 2nd grade. Consideration of the relationship between the differences in physical environments and in diversity in each intertidal zone could address this concept.
The cross-cutting concept Patterns that is also emphasized in 2nd grade is also a relevant.