Approaching Cattle Point

(The Cattle Point Crew, 2000: Barb, Joe, Owen, and Lindsey)

Although on first approach the intertidal region at Cattle Point might look unstructured and chaotic, each zone between the high and low tide marks harbors unique animals and communties.  Some exercises we describe below involve simple search and discovery, and others more quantitative sampling.  Even when rigorous counts are not being made, use of a line, marker, quadrat or transect can help to focus attention on particular animals or areas.

One way ecologists quantify the number of species in an area is by counting the number of creatures in randomly selected locations.  At Cattle Point one can run a transect line, composed of nylon rope or a waterproof tape measure, from the high tide line to the low tide line. Once this line is marked, a square frame, or quadrat, can be used to count all species along the line.  (Less quantitative sampling might involve simply recording organisms that fall within a foot of the line).  In order to save time and effort, the frames (we used a 0.5 meter x 0.5 meter PVC frame) can be randomly placed along the transect line. In these frames, all the animals can be counted--or estimated if there are too many to count (in some quadrats we estimated that there were more than 600 spirorbid worms). The cover of algae can be estimated by sight, or by using a point-count method, where the percentage of string cross-hairs overlying algae is used as an estimate of overall cover.
At Cattle Point students should be encouraged to explore the intertidal area. But before they begin looking in crevices and walking along the shore, be sure to warn them that rocks along the edge of the tide can be slippery, and barnacle plates can rip skin and clothes.
Students can begin their studies by searching the intertidal area for organisms, some of which have been introduced by the instructor and some that the students can discover for themselves. They should note the habitat where they find the organism and look at their structures or body plan. What makes a particular species partial to a given habitat? How do the organisms move about and feed?
Below are three activities that can be undertaken while visiting Cattle Point: the first explores diversity, the second abundance, and the third allows the students to draw their own conclusions about Cattle Point.
I. Introduction to the intertidal
A.  Use information at this website to have students summarize the importance of several physical parameters:

B.  Introduce students to the three main habitat types II. Introduction to microhabitats

Have students use information in this web page to understand how variation among microhabitats relates to variation in physical parameters

III. Seven Phylum Scurry

Scavenger hunt

Students should work in groups to explore the intertidal area for themselves. Time allotted for this hunt is 30 minutes.  Some species are fairly common at Cattle Point--the list below can be formatted as a checklist, with students noting whether species were found in a tidepool, along an exposed area, in a crevice, or in a surge channel.

Also, have students guesstimate how many individuals of a common species, such as a barnacle or chiton, are found in a typical square meter. (Click here for a scanned copy of the worksheets used for exercises III and IV during the 2000 MIZ class field lesson).

IV. Billions and billions
"There are billions in this pond."  --Owen displays his numerary skills at
Handy Joe's Crab Den, estimating the number of feather duster spirorbid worms.
Next he'll be barred from Sands Casino for counting cards.

Quadrat Analysis: have different groups of students analyze the number of a common organism in a square meter.

Goal: To estimate the number of barnacles (or chitons, or limpets, etc.) per meter square.

Procedure: Count the number of organisms in a quadrat.  We used a 0.5 meter by 0.5 meter square with 25 equal boxes of 100 centimeter squares, but any standardized quadrat can be used.  The procedure should be repeated in random locations.   Students should compare there original estimations with what they found by counting actual organisms. Why are barnacles usually quite dense, whereas chitons and other organisms are more sparsely distributed?  How could you estimate total abundances of species at Cattle Point?
V. Cattle Point Haiku

QUESTION: A scallop has only one adductor muscle. What is the sound of one shell clapping?

Marine ecology and observation is more than field guides, taxonomy, and quadrats. As a final exercise, students are encouraged to work alone or in groups to reflect on their time at Cattle Point.

Haiku is a traditional Japanese verse of three lines and seventeen syllables, which refers to nature and the seasons. Often a moment in the poem presents a revelation for the poet, as in the seventeenth-century poet Matsuo Basho's famous work

An old pond.
A frog jumps in,
Sound of water.

This is a translation from the Japanese, which in translation doesn't follow the rules.  Cattle Point students, however, should follow the original form:

five syllables
seven syllables
five syllables

A traditional haiku always mentions a season or refers to one. Your poem should be seasonal. You can mention summer in your poem, or make a reference to it: hot weather, long days, mosquitoes, even sun block.

Since we are requesting a Cattle Point haiku, students' poems should mention an organism they found here or refer to their experience at the point.  Groups can collectively submit one poem or up to one haiku per person.

Equipped with a few simple tools and field guides (see references below), a number of research questions could also be addressed:

  1. Is the recruitment of barnacles, a ubiquitous animal covering many hard surfaces in the intertidal, uniform throughout the Cattle Point environment? What are the forces that determine barnacle coverage?
  2. Although the temperature and salinity are similar in the upper and lower tide pools, are different species found in different areas?
  3. Why is algae absent in the upper tide pool?
  4. Does sea grass reduce wave action? If so, how?
  5. What factors allow the anemeone Anthopleura to be common in certain parts of intertidal?
  6. Why are limpets and snails the dominant species in the upper tide pool?
  7. How does algae affect the chemical composition (oxygen, carbon dioxide, salinity) of tidepools?
  8. Many of the species at Cattle Point are relatively small. How might size affect desiccation rate?
  9. Cattle Point's position at the intersection of the Strait of Juan de Fuca and the San Juan Channel presents an opportunity to study the pelagic distribution and settlement patterns of local organisms. Both bodies of water have strong currents that can spread larvae throughou the San Juan Islands. Do you think the larvae of animals found at Cattle Point also tend to settle there. How would you determine this?

Brusca, R. C., and G. J. Brusca. 1990. Invertebrates. Sinauer and Associates: Sunderland MA.

Jensen, G. C. 1995. Pacific Coast Crabs and Shrimp. Sea Challengers: Monterey, CA.

Kozloff, E. N. 1993. Seashore Life of the Northern Pacific Coast. University of Washington Press: Seattle, WA.

McConnaughey, B. H., and E McConnaughey. 1998. Pacific Coast. National Audubon Society Nature Guides. Chanticleer Press: New York.

Pentcheff, N. D. 1991 Resistance to crushing from wave-borne debris in the barnacle Balanus gladula. Marine Biology 110: 399-408.

Rupert, E. E., and R. D. Barnes. 1994. Invertebrate Zoology. Saunders College Publishers: New York.

Stachowicz, J. J., and M. E. Hay. 1999. Reducing predation through chemically mediated camouflage: Indirect effects of plant defenses on herbivores. Ecology 80:495-509.

Warner, G. F. 1977. The Biology of Crabs. Van Nostrand Reinhold: London.

Wicksten, M.K. 1980. Decorator Crabs. Scientific American 242:146-154.

Tide Tables

Cattle Point Lighthouse

Animal Diversity Web

Friday Harbor Laboratories

Other Habitats at this Web Site