this section is on hermit crabs[picture at bottom] at the moment I have 2 hermit crabs that are about 3cm long and these crabs can get to be 20 cm long [this is very rare] .they are quite easy and inexpensive .they require little care . You must wet their sponge 1 a day [it must be a special natural sponge ].you must have a food dish that should be emptied once a week you can feed them fruit veggies and there are commercially prepared foods . My suggestion is that you give them the commercial food as little as possible. What is also a good idea is to get them cuttlebone it can usually be found in the bird section of your pet store.uttlebone is the inside of a cuttlefish made of much needed calcium. You must grind it up and put it in small lids .you should also make sure the crabs are similar sizes cause they will fight .The last part of keeping a hermit crab is getting them a sand box just to dig in. One last thing is the aquarium I would say 3-4 crabs in a 5-gallon aquarium. Also keep in mind they are social creatures and are happier in groups of a couple, and remember they are nocturnal. The last thing to know is that you should not use gravel as a floor or they will hurt their feet I suggest carpet or sand, and do not worry if you buy one and it is missing a leg it will grow back the next time they shed.You should alaways have a waterbottle to mist their aquarium and that is the basic supplies and information that you need