Hermit Crab Bullying and How to Avoid It in your Crabitat
Hermit crab bullying is a fairly uncommon behavior and usually an indication of issues inside a hermit crab pet enclosure. However, bullying does also occur in the wild, though it is rare.
Bullying is more prevalent with certain types of hermit crabs. Purple Pinchers, the most common type of hermit crab within the U.S. pet industry, are widely considered to be the most peaceful and non-confrontative.
Hermit crabs are social creatures and prefer to live in groups (called “casts”). In the wild and with unlimited space, hermit crabs live in groups of 100 and more. It’s very rare for a hermit crab to injure or kill another hermit crab.
However, aggressive behavior and bullying can happen. Although this behavior is uncommon, it’s important to recognize the signs, understand why this could happen, and find ways to avoid it.
It’s also important to note that sometimes, what looks like “bullying” is just normal hermit crab behavior.
What does Hermit Crab Bullying look like?
Bullying or just curious and friendly?
A common observable behavior is one hermit crab turning over another hermit crab. It looks like a bully – victim situation at first glance. The “victim” immediately curls up inside his shell with his large claw protecting the opening.
But this behavior rarely ever results in injury. Hermit crabs are very curious by nature. Most of these instances seem to be a result of curiosity. It could be a larger hermit crab exerting an alpha behavior, establishing some sort of dominance.
Some hermit crab pet owners observe older, larger hermit crabs that have lived alone for long periods of time bullying new smaller hermit crabs introduced into the crabitat – which would indicate a territorial behavior. However, it’s also been commonly observed that these older, larger hermit crabs can also befriend and act as a “mentor” towards smaller, newer hermit crabs.
Because there are so many conflicting stories of territorial behavior being the reason for bullying behavior in crabitats, it’s hard to know for sure if this is conclusive.
Most common causes of bullying in a Hermit Crabitat?
- overcrowding
- lack of extra shells
- introduction of new hermit crabs
Bullying among hermit crabs isn’t common. If bullying is occurring in a hermit crabitat, it’s usually an indication of overcrowding, a lack of extra shells or there’s a need for strategic intervention when introducing new hermit crabs into an established crabitat. But watching for bullying behaviors, and taking measures to provide good basic care and a safe and healthy environment for your hermit crabs, you can help to prevent bullying from happening.
How to prevent Hermit Crab Bullying
Careful with overcrowding in crabitats!
Hermit crabs need space! They need space to climb and explore. But most importantly they need space where they can safely burrow into the substrate, create tunnels, and molt. This is an essential part of their life cycle. When a crabitat is overcrowded, hermit crabs won’t have the space they need for their most basic activities and needs.
Hermit crab pets are so cute, we agree! But two or three are just as cute as five or six… if their crabitat isn’t very big. While it’s possible to have a healthy 10 gallon hermit crab tank in the short-term, for very small hermit crabs… they grow fast. A 20 gallon tank is the better minimum size for small hermit crabs, with the understanding that you’ll need to upgrade to a bigger enclosure in a couple of years. The larger the habitat, the more hermit crab pets you can safely place inside.
Surface molting and over exposure!
There are times when a hermit crab tries to molt on the surface of their substrate. This is rare, but worrisome when it happens. Other hermit crabs could threaten and harm an exposed hermit crab. In these instances, it may be necessary to help protect that crab’s exposure and vulnerability. Some crab owners have had good results by cutting a 2-liter soda bottle in half and placing half surrounding the vulnerable crab, not allowing other crabs to come in direct contact with the molting one. Make sure the crab can still breathe and don’t keep it in long, because that crab will want to eat and drink soon enough.
If this happens, remember that this isn’t normal behavior. Hermit crabs burrow in substrate in order to molt. If it’s happening on the surface, make sure it isn’t due to overcrowding or issues with the substrate.
Hermit crabs want lots of extra shells to choose from!
Hermit crabs can’t live without shells. An essential part of their life cycle is molting to grow, and upgrading their shells with larger ones as needed. Also, hermit crabs love to try on new shells until they find the right fit, weight and shape they like best. (yes, funny enough some hermit crabs act like women and shoes… they like to have lots to try on, until they find their favorite(s)!)
If there aren’t enough extra shells to choose from, a hermit crab could potentially start bullying another hermit crab for their shell. It’s always a good idea to keep 3-5 extra shells for each crab, at all times inside the crabitat. These extra shells should all be similar in size, some slightly larger and if possible, also in different shapes and weights.
Example: turbo shells are usually the preferred shells for larger purple pinchers. Why? They have a circular opening, medium weight and narrow curve that easily fits their abdomens. Some lighter weight shells, or elongated curves in shells don’t work as well for hermit crabs because either they don’t feel as secure, or they are more difficult to climb and maneuver in, in small spaces or tunneling. Find more information and tips on hermit crab shells, here!
Adding new crabs to an established crabitat with older hermies...
Many hermit crab pet owners have reported bullying issues when they added a new hermie to a crabitat with one older hermie that was alone for a long period of time. Full disclosure, I (author of this post) have never had this happen.
BUT also full disclosure, my crabitat is fairly large and not overcrowded. So it’s certainly possible that bullying can happen if there is an alpha hermie being expected to befriend a new hermie, but it’s most likely very rare.
As well, lots of owners have reported the opposite of this potential bullying situation! Older hermit crabs that have been alone, having new hermies added to their crabitat, often become friends with and act as a sort of “mentor” of these new smaller hermit crabs.
What about adding a large hermit crab in with another large hermit crab? Or what about adding a large hermit crab in with a few small hermit crabs?
Generally speaking, if your crabitat is large enough, with plenty of substrate and climbing (and hiding) opportunities… it will all work out just fine! Check out or blog post on adding new hermit crabs to a crabitat for tips and tricks.
In conclusion:
Hermit crabs are social and like to have friends, often hanging out close together. BUT they also need their own space particularly for molting. When overcrowded, a crabitat can become challenging to these natural instincts and needs and can result in hermit crabs becoming aggressive, and possibly causing injuries by fighting. Provide space, lots of extra shells, and learn your hermit crab’s normal behaviors… so you can recognize when something is wrong and work to protect them.
Last update on 2024-04-27 / Affiliate links / Images from Amazon Product Advertising API