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?