Food preference in land hermit crabs (Coenobita sp.) when given choice of meat or
vegetables
Whitney Jardine, Sarah Park and Nataya SmithBIOL 3401
Mount Allison UniversityNovember 22, 2013
Hermit Crabs
• Land hermit crabs (Coenobita sp.)• Gastropod shells for protection• Scavengers • Locate food by olfaction
Purpose
• To determine food preference in hermit crabs when given choice between meat and vegetables
Previous Studies
• Visually orient food and conspecifics for social facilitation of foraging (Kurta 1982)
• Wide array of food (fruit, leaves, dead animals,etc.) (Burggren & McMahon 1988; Brightwell 1950)
Previous Studies
• Optimal foraging theory: scavengers selecting nutritionally balanced diet (Stephens & Krebs 1986)
• Negative preference induction (Thacker 1996)• King crab, Asian shore crab, squat lobster and
crayfish found to prefer meat diet (McLaughlin & Hebard 1959; Brousseau & Baglivo 2005; Karas et al. 2007; Correia 2003)
Hypotheses
• Spend greatest proportion of time in meat zone
• More likely to spend more time in the zone with conspecifics
Method
• 11 land hermit crabs • Starved for 4 days prior to study• Testing done in evenings with overhead lights
off• 1 red lamp between two testing tanks• Tanks divided into three zones
Method
• Hamburger, chicken, ham, and tuna in meat zone
• Spinach, carrot, lettuce, asparagus in vegetable zone
• Crabs were placed in center of tank and gave them 2 minutes for acclimation
• Observed for 15 minutes, recording location every minute
Method
• Individual trials once with each crab
• 4 group trials
• Cleaned tank between each trial
• Switch food to opposite ends for half of trials
Results
Figure 1: Mean percent time spent in each tank section across 11 individual hermit crab trials (n=11). Each trial lasted 15 minutes.
Results
Figure 2: Mean percent time spent in each tank section across 4 group trials (n=11). Each trial lasted 15 minutes.
Results
Table 1: Results of chi square test for differences in percentage of time spent in each zone (meat, no food, vegetable) Critical value 5.99.
Discussion
• More time was spent in the vegetable zone than meat zone for individual and group trials
• Did not support our first hypothesis (choosing meat over vegetables)
• Did support our second hypothesis (social foraging)
Discussion
• Non-significance likely due to no food zone
• Different species of crab than previous studies
• Negative preference induction
• Vegetables easier to ingest quickly
• Benefits of social foraging
Questions?