Materials and Methods
Introduction Materials and Methods Graphs and Tables Results
Discussion Background Information Pictures References


  •  2 watches for timed data collection
  •  2 buckets for collection of shells
  •  Pen and paper for recording shell species
  •  Approximately 4 small bowls used for shell separation
  •  Dr. Mangin’s expertise for shell species identification
  •  Water shoes for inter tidal region
  •  Four flashlights


  • The experiment was performed at Station Beach in Puerto Peñasco, Mexico between 8pm and 10pm on September 29th, 2007.
  • The ocean was ebbed 3ft during the experiment.
  • The group of four was split into two groups  with two members each
  • Group 1: Jenessa and Liana Group 2: Jenny and Chewie
  • Group 1 was assigned coquina rock for shell collection in low elevation for approximately 10 minutes. This location was as close to the water as we could get, if not in the water meaning zone 4.
  • Hermit crabs were collected by hand, and put into buckets for later counting. Any crabs seen were collected, under and on top of rock types. Number of turned boulders were subjective due to the amount of crabs on top of boulders
  • Group 2 was assigned basalt rock for shell collection in low elevation (zone 4) for approximately 10 minutes.
  •  After the allotted time, the groups switched rock type and collected for another 10 minutes in low elevation. So, including the initial 10 minutes period and the final 10 minute period, there was a total of 20 minutes collection time, between the two groups, for each rock in low elevation.
  • All shells were taken to the beach for separation and counting according to species type. Katrina Mangin helped us to sort and identify the shells to the species. Most of the shells by far were occupied by hermit crabs; less than 10 were occupied by snails. These were not included in the analysis. All species and number of shells found of each species were recorded
  •  All previous steps were repeated for middle elevation collection and analysis. This location was more in the middle of the reef, meaning lower zone 3.
  •  Morula and Costanachis species were grouped together due to time constraints in counting and the high number of both species during the counting of species.
Authors: Jenessa Hill & Jennifer Mordaunt| Ecology 450| Marine Discovery| Created November 20,2007| University of Arizona| Class photos