HCA: Hermit Crab Association

My summer homework for science was to design a hypothetical experiment. I did mine on (what else?) hermit crabs. The Fastest Species Of Hermit Crab 1. Question: Which species of hermit crab is the fastest?2. Research: There are many different species of hermit crabs, but the two most common ones kept as pets in the US are Coenobita clypeatus (“Purple Pincher”), and Coenobita compressus (“Ecuadorian”). Ecuadorians are hyperactive and extremely social, whereas Purple Pinchers tend to be more tolerant of fluctuations in humidity and/or temperature. (Sources: landhermitcrabs.com, www.tonycoenobita.com/ species_eng2 .htm)3. Hypothesis: Since Ecuadorian crabs are more energetic than Purple Pinchers, they will be faster.4. Independent Variable: The type of hermit crabDependent Variable: Speed of the hermit crabsConstants: Food, care, water, crab habitat (AKA “crabitat”) conditions, size, age,and type of shell on each hermit crab (probably impossible to do in real life, but this is all hypothetical, right?)5. Materials: Three properly taken care of C. clypeatus, three properly take care of C. Compressus, one hula hoop, a flat surface on the ground (cardboard, wooden floor, etc.), three shoeboxes or other containers labeled 1-6, a stopwatch on a phone or tablet, pencil and paperProcedure:1. Set up your paper as shown on the next page,2. Lay the hoop on the flat surface.3. Take a hermit crab and carefully place it in the center of thehoop.4. Start the stopwatch.5. Stop the time when the hermit crab reaches the inner edge ofthe hoop, and place the hermit crab in its designated container.6. Repeat steps 3-5 for each individual crab three times.Can you guys please give me some feedback on this? I need to make sure all the information is correct.Thanks!

there are some variables that you can not control or have as constants.... the age of hermit crabs is not really known as each species grows at different rates and the size of each species is different as well. While a crab that is roughly 3 years old in one species may be about the size of a quarter one the same age may be about the size of a dime. We are not really sure how quickly crabs grow each year and each crab usually prefers a different kind of shell. so these would have to go into independent variables. The rest of it seems right though. They could possibly be considered constant though if you could prevent the crab from changing shells though and it is noted that what kind of shell each crab is wearing and how much the shell roughly weighs. Hope this helps.

Thanks! I have made those changes.