Originally written by Vanessa Pike-Russell
Look closely at the hermit crab environment and ask questions about the food, bedding, housing and temperature needs for your new pets. If you have never owned hermit crabs before a book on caring for hermit crabs is a wonderful resource. There is a list of hermit crab guides listed under Books in Product Reviews. Make sure that you can purchase extra shells from the shop or alternatively from a seashell shop, craft store or tourist shop.
When I am selecting a crab I will ask permission to pick up and handle the hermit crabs. Slowly and gently pick up any available crabs from the tank and fluidly lower them onto your palm, stretched flat. It is important that you keep your hand flat as most hermit crabs see you as a giant and are afraid you will drop them! Considering the ease with which they fall I think that they are justified in this fear. You need to be ready at all times to catch them in case they tumble off your hand.
Watch each crab as it meanders across your palm. Sometimes it takes a while for a crab to looe its initial fear of you and peek out from the safety of its shell. Try to keep your hand still and talk soothingly to your crab, always remembering to place your empty hand alongside the other at the edge the crab is crawling towards.
Examine each crab closely for factors of ill health, such as:
*Does the tank have a strong, fishy smell…(something like two day old fish sitting in the sun)
*Are there any flies, pests or mites on the hermit crab or inside the enclosure?
*Are there fungus or mold spots on the hermit crab?
*Has the crab lost more than one limb?
*Is the crab overly inactive?
*Does the crab seem aggressive?
* Does it have both chelipeds(grasping claws)?
*Is the shell too large or too small for the crab?
*Is the shell broken and ill fitting? Studies of clypeatus in Curacao indicate that hermit crabs with broken or ill fitting shells are restricted to the coast and must rely on saltwater for drinking and are generally in poor health. 
*If this is not your first crab will it be a good match for your other wards?
*Do you have suitable-sized shells for your new ward
*Do you want a small crab, suitable for handling by smaller children, or do you want a larger crab?
Crabs are Dead or Moulting
A strong fishy smell could mean that the hermit crab has passed on or is in the middle of a moult. It is best to avoid crabs which are moulting when purchasing a new pet as such crabs as it usually ends in heartache because of the stress on an already weakened crab. If possible, ask the pet store to make an isolation unit within the tank, perhaps a 1/2Gallon/2Litre Small Pals Living World Deluxe tank filled with sand/coral sand/fine river pebbles or T-Rex CalciSand.
1. Wilde, 1973