What species of crab do I have?
What Kind of Hermit Crab do I Have?
In the United States there are two main species commonly sold as pets. The descriptions below describe those two. Coenobita clypeatus. It is native to the Caribbean and has many common names, such as purple pincher (abbreviated to PP), land hermit crab, tree crab, soldier crab, and Caribbean crab. The second species is Coenobita compressus, whose common names are Ecuadorian Crab, E-Crab, E or the affectionate nickname, "Eccie." It is highly likely that if you live in the United States, you have one or both of these two species of crabs. However, if you purchased your hermit crab from a mall kiosk or a Petco, there is a very good chance that you could have what is called an "exotic breed" of hermit crab. The exotics are imported to the United States from the Pacific Rim. If you view the identifying information below and it does not seem to fit or look like your crab, please visit the Exotics webpage for information on identifying your exotic land hermit crab. I suggest you review the Exotics page anyway, because it will help you make a more definitive identification of your land hermit crab.
How Can I Tell Which is Which?
There are a few key differences between the two species, First, let’s take a look at some pictures of Purple Pincher crabs.
As you can see in the picture of the PP crab to the right, he has a large, purple claw. Usually the claw has a lighter-colored tip, but not always.
Now we will view a second difference in the two species of crabs.
See the PP crab in the picture to the left? He has many speckles on
his legs and claws. The speckles are sort of the hermit crab equivalent of
hair follicles. They are called setae. Setae are hair-like filaments of
chitin, the material that makes up the crab’s exoskeleton. They do not ‘grow’ from the exoskeleton, like a human hair grows from a human scalp, but are shed along with the exoskeleton during the molting process. Typically, a PP crab will have more setae on its body than an Ecuadorian crab (which only has small tufts on the front edge of both claws.)
Now look at another PP crab in the picture to the right. You can see
in the 
highlighted circles how round this crab's eyes are. He is another purple pincher crab. Purple pincher crabs have very round eyes, but may have a slightly flattened lower portion to the eye. For this reason you should not rely on eye shape alone in determining the species of your crab. Look at all the other elements discussed here, body shape, setae coverage, claw coloring, etc
PP crabs’ usually have a brown/tannish head, and legs a darker purple/brown with more with more red or orange. The smaller crabs especially will have a tan head with a dark ‘spot’ in the center. In particular, the left-most walking leg, as pointed out at the top of the page, is specially adapted to fit around the large claw, is heavily armored and usually colored a deeper color than the rest of the body with an orange/yellow tip
Moving on to the identification of the Ecuadorian crabs, check out the picture to the left. Note specifically the elongated eyes, striping on the sides of the
head, wider, flatter thorax, same-colored claws and darker leg tips of the
Ecuadorian crab to the left, and compare them with highlighted, round eyes of
the purple-pincher crab picture above. Big difference!
The short answer is, "Yes!" In their native habitat, PP crabs live inland, away from the seashore. They are used to living on whatever falls to the forest floor and they drink from puddles of rainwater. On the other hand, the crabs native to Ecuador live on the Pacific seashore around the tidal pools and high-tide-zone. Their bodies have adapted to this seashore existence by becoming able to metabolize the salt in seawater. In fact, they’ve adapted so well to their environment that they actually need seawater to live.
I Live Miles Away From an Ocean, Does This Mean My Ecuadorian Crab Will Die Because I Can’t Get Him Sea Water?
Technology being what it is today, people are able to maintain man-made reefs with complete food-chains and ecosystems in their aquariums. Obviously, it isn’t financially feasible for salt-water aquarium enthusiasts to have gallons of sea water shipped to them at home. So, aquarium-product manufacturers got wise and analyzed the chemical make-up of ocean water, and then formulated an acceptable substitute. You can find many brands of synthetic sea salt in pet stores today. The brand most land-hermit crab owners use for their Ecuadorian crabs is called "Instant Ocean." There are other brands available (Doc Wellfish, etc.) which are perfectly adequate. Sea salt is sold in large quantities, to enable people with reef systems to mix 30-100 gallons of it or more. Because of this, the smallest amount of sea salt you can buy is a 5-pound box.
How Much Sea Salt Should I Use in Their Drinking Water?
Before you can even add the salt, you must first neutralize any chlorine or metals present in the water. For this, you will need a good aquarium water dechlorinizer. There are many names available on the market: Tap Water Conditioner, Ammo-Lock, etc. Try to purchase one that gives the directions for mixing up a gallon of water, or you’ll have to do a little math to figure out the correct ratio of drops per gallon. Once you’ve dechlorinated the water, then you can add the salt.
Follow the Package Directions
If using Instant Ocean, the ratio would be ½ cup of salt per gallon of water. This breaks down to ¼ cup per half-gallon. It is convenient to mix a whole gallon of saline water and then use it for the next month or so. If you decide to mix a gallon of the saline solution, be sure to mix it well before each use so the salt doesn’t settle in the bottom of the jug. Also, before shaking it, open the cap and take a deep sniff to make sure it has no smell. If the water gets a smell to it, throw it out and mix another batch.
This method has been extensively tested and found to work well with Ecuadorian crabs. Some people might tell you that this ratio is too strong -- don't be fooled! Many folks don't realize is that it if the water you provide is considered by the crabs to be too salty, they will drink unsalted water to balance the amount of salt in their bodies. I've read study after study about their fascinating method of saline and water regulation. Crabs given the choice of 0% saline (completely fresh) water and water of 200% salinity will ingest amounts of both and regulate their saline that way. Their bodies are marvels of osmosis and perfectly suited to adjusting their internal salinity. However they can't balance what they don't have. If they do not have enough salt and therefore can't retain water, they will suffer. So please provide your Ecaudorian crabs with the saline water they so desperately need!
Put the saline water in any non-metallic dish, as you would non-saline water. You may or may not want to put a sea sponge in the saline, depending upon your preference. Some people have found that placing a sponge in the saline water causes the sponge to foul faster and develop a rotten-egg-type smell. If you find this to be a problem, you may want to invest in some small round pebbles or marbles to put in the water dish. That way if a small crab tumbles into the water dish, he will have something to crawl on and won’t drown. Watch your Ecuadorian crabs’ reaction to the saline water. They are very good at discerning between saline and fresh water and you’ll see them walk over to the saline and place both pinchers into it and make ‘shoveling’ movements. The shoveling causes the saline water to rise to the crabs’ mouth by a capillary action using the setae on the inner sides of the crabs’ claws. The maxillipeds (mouthparts) are extended to direct the water into the mouth and also into the seashell. So what you’re seeing when you’re seeing the ‘shoveling’ is actually the crab filling its seashell with water. You may notice your Ecuadorians ‘pee’ on you more often than your PP crabs. The ‘pee’ is actually the shell water which is accidentally squeezed out when the crab is frightened and quickly withdraws into its protective home. HELP! My PP Crabs are Drinking the Saline!
Relax! This is not only normal, but it is RECOMMENDED that the PP crabs to have access to both fresh and saline water. The salt content helps to maintain the correct ion balance in the crabs’ ‘shell water.’ If you offer your PP crabs both saline and fresh water, you will see them drink from both dishes. The crabs can detect the presence of the saline, and will only drink it if they need it.
My Ecuadorians are Hyperactive!
It is well-known that Ecuadorian crabs are usually about 50% more active than similarly-sized PP crabs. They run much faster than PP crabs and can seem to run in all directions at once -- forwards, backwards, even sideways! They also really enjoy climbing on anything in the tank you provide for them. Some of the smaller Ecuadorian crabs have been known to grasp the silicone sealant in the corners of the aquarium (which holds the panes of glass together), and, by climbing, claw-over-claw, actually climb the glue and escape the tank. You should have a well-fitting lid on your crabarium, and this is even more important when you have Ecuadorians.
They Make Noise!
Yes, they do! Ecuadorian crabs often communicate with each other by a squealing, chirping noise, especially when one crab climbs on top of the other. It is not known how they produce this sound, which can be quite loud and insistent! Don’t worry if your Ecuadorians chirp a lot, unless you hear the chirping getting louder and louder, and realize there is a ‘shell fight’ going on. Of course, in the event of a shell fight, you should separate the crabs, for the safety of both of
them. If you want to read up on their fascinating vocalizations,
click here to find out more.
My Ecuadorian’s Shell is Way Too Small, but he Refuses to Change!
It’s a common complaint of owners of Ecuadorian crabs that they don’t like to switch shells as often as the PP crabs. As you may have noticed, your Ecuadorian crab is in a shell with a more slotted opening than the PP crabs’ shells. Ecuadorians have a wider, flatter-shaped abdomen, which is why they prefer shells with slot-shaped openings. They have a special preference for shells from their native habitat. If you are purchasing Ecuadorian crabs for the first time, it is strongly advised that you select some recently-vacated shells (with slot-shaped openings) from the pet store where you bought your Ecuadorian crab, since it is likely that you will not have any of their ‘preferred’ shells at home.
Anything Else I Should Know?
Only this -- Ecuadorian crabs really like to have the company of their own species, so if you are interested in purchasing one, it is strongly recommended that you purchase him or her a friend. They actually seem to slow down in activity and get ‘depressed’ when they are without another Ecuadorian ‘buddy.’ So please, do not buy just one.
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