Are hermit crabs looking for light and large shells?: evidence from natural and field induced shell exchanges
Jose- Luis Osorno, LourdesFernandez- Casillas, CristinaRodriguez- Juareza
Department of Zoology, University of Florida, 223 Bartram Hall, Fainesville , Fl32611, USA
Departamento de Biologia, Facultad de Ciencias, Universidad Nacional Autonoma de Mexico , Mexico D. F., C. P. 04510, Mexico
Departamento de Ecologia Evolutiva , Instituto de Ecologia, Universidad Nacional Autonoma de Mexico A. P.70 275, Mexico D. F., C. P. 04510, Mexico
Received 15 October 1996; received in revised form 9 May 1997; accepted 3 June 1997
Terrestrial hermit crabs(Coenobita compressus( H. Milne Edwards)) on Isabel island, Mexico, prefer Nerita(Ritena) scabricosta(Lanark 1822) over other species of shells.
Nerita scabricosta, the lightest species of shell, has the highest internal volume/ weight ratio( IV/ W ratio) of all species available at the island. Heavier shells( low IV/ W ratio) are more costly to carry and may restrain growth. We hypothesized that crabs will search for shells with high IV/ W ratios to save energy, and predicted that in every individual shell exchange crabs will prefer a shell with a higher IV/ W ratio. Observations of spontaneous aggressive shell exchange interactions in nature between crabs carrying preferred shells (with high IV/ W ratio) and crabs using less preferred species of shells (low IV/ W ratio) support this idea. By inducing individual shell exchanges in the field, we experimentally confirmed the preference for shells with high IV/ W ratio, and we also showed that crabs prefer larger shells over those they were bearing. Moving to a larger but not heavier shell may facilitate growth though saving energy that would otherwise be spent in locomotion. High growth rates seem to be advantageous because size is a correlate of fertility, since large males apparently have more access to females, and large females produce larger clutches, thus indicating the possible reproductive benefits for preferred light and large shells.
1998 Elsevier ScienceB. V.
Information related to this article:
Nerita scabricosta is also known as the ‘ornate nerita’.
Recently we interviewed Amy Youngs, a young artist who has “collaborated with another artist, Matt Derksen, to design shells using 3D modelling programs.”
What prompted you to create prototypes of hermit crab seashells
I am very interested in the ways that technology interfaces with the natural world and I when I was given the opportunity to work with the new technology of rapid prototyping, I really wanted to make something that would connect with my interest in living things. I remembered owning a hermit crab and I knew that they switched shells and I had been curious about how they make their decisions as to which shell they would select, so I decided to try to design some for them to choose from.
What was the process you went through to get to the current prototype design?
I collaborated with another artist, Matt Derksen, to design the shells using 3D modeling programs. We used Cinema 4D and Form Z software to do this, then emailed the computer files to John Marshall, the artist who had access to rapid prototyping machines which can “print” 3D computer files into objects. He and Cezanne Charles curated the Intersculpt 2001 Exhibition in Dayton Ohio, which fortunately gave artists access to this rapid-prototyping technology.
What are the prototypes made from?
Photopolymer, a kind of plastic that cures when a laser beam hits it.
Why did you choose that material to make the prototype from?
This was the technology I had access to. During the exhibition however, there was another kind of rapid prototyping machine running called a Thermojet, which uses wax to make objects, so there were 2 more shells made in this way by Matt Derksen. Those were not given to the crabs, though. I think Matt was attached to them and maybe a little worried that the crabs might get sand embedded in the wax.
Have any of the hermit crabs moved into your seashell prototypes?
No. This was a little disappointing at first, since I was really looking forward to seeing the crabs in the human-designed shells. But now I am glad because their rejection of the rapid-prototyped shells has been an interesting kind of humbling experience that I think we humans sometimes need. I am reminded that they know so much more than I do about what they need and this process is helping me understand what they do not need. I learned that they prefer smooth shell interiors, for instance, but the rapid prototyped shells have ridges that are probably not comfortable for them and there is an odor that they may not like. They have challenged me to make new versions. I had some handblown glass shells made for them, because I had read about that phenomenon of crabs moving into those miniature glass liquor bottles littered on the beach. So perhaps they like glass, or perhaps it is still not as good as a real shell. So far they have not selected any of the glass shells to move into. Perhaps they do not like that light goes through them, or perhaps they are too heavy…
In the photo on your site I can see prototypes in the shape of fingers, what made you think of a finger-shaped shell?
Since the project was conceived as a collaboration between crabs and humans, I thought it would be most interesting to see the crabs carrying around “human parts” like noses, fingers and thumbs. Also, I thought humans, who are known to enjoy seeing themselves reflected in technology, would also appreciate the crabs more if they saw images of themselves on the crabs.
We did make a video that showed what the crabs might look like if they did choose to move into our shells, though, which people thought was pretty funny. In the video, the crabs do not move around much, but every once in awhile a crab with a big toe shell walks though the scene.
Will you be creating more prototypes?
Right now I am caught up with other projects, but if I think of a new material that crabs might like better than plastic or glass, I might try that. If anyone has any suggestions, I’d be happy to hear them!
If you were a hermit crab, which prototype seashell would you choose?
Probably the thumb shell, because I think it is strangely elegant, although the nose shell is pretty stylish, too. I think the nostrils are too small though so I would have to be a “fashion slave” crab to squeeze into it.
Thanks for agreeing to take part in this interview.
Our treatment of animals will someday be considered barbarous.
There cannot be perfect civilization until man realizes that the rights
of every living creature are as sacred as his own” – Dr. David Starr Jordan
and now, on with the show…
Crab in a cup anyone?
First a bit o’ the story. I went to the pet store, the one that I LIKE, and they always have good patties, in natural shells, none of the painted. So I wander to the hermit crab tank and in the aquarium is about 16 crabs in cups, stacked on top of each other. all in red or pink heart shells. One of the employees walked by and I said,
“Um… why are these in cups?”
“Oh, it’s just for valentine’s day”
“But…why don’t you free them, this is exactly what walmart does” *frown*
“Well we haven’t had TIME.”
“Dood, it’s your JOB to take care of the pets.”
He went to help someone else. So over comes a girl, and I said,
“Ooh, I guess i’m going to get one. Can I look at them?”
She said, “Sure, go ahead”.
And the guy comes back and said,
“Oh, when you have time can you open all those containers?”.
So she did, while i’m politely bitching about their stupid painted shells they are now having. I helped her free them. I was going to get one that was staring at me through the bucket, and making praying pinchers. She freed her before I could say I wanted her and the little pattie was happily roaming so I looked on and decided on booger, because of the blob of boogery paint by her eyes. More on her later.
So I went in search of another in need. Found one dead, and then came upon my newest rescue. I could tell by looking he was stuck. Generally, if a hermit crab doesn’t at least come out to check you out, they’re either stuck, sick, or dead.
So I told her, “He’s stuck you know.”
“Um, yeah, he can’t move.”
I took him home, got home at 5:55pm, gave them a quick bath, in which he did not move one little bit. Only his big pincher moved so I knew he was alive. I could only see 3 of his 6 supposed to be seen legs.
So yeah, freeing a stuck crab is just about as intricate, daunting, nerve-wracking, and time consuming as brain surgery. I use cuticle nippers that have a sharp point and let’s just say, I learned my lesson the hard way.
For one thing – why do they paint the inside of the shells? It CEMENTS their bodies and legs to the shell they’re forced into, and they are so traumatized in the ‘factory’ that i’m sure a good majority of them hide asap. To their detriment, obviously. Crabs are not pliable, they are hard crustaceans with not a lot of options once they get in such a predicament.
From first clip to last it was a full three hours. I took a one minute break, and went right back at it. I knew I was stressing him out, but I guess I’d rather do that all in one fell swoop, than to free him bit by bit and leave him almost free, which I thought about doing, but. I didn’t.
He was by far my worst stuck crab. Tucker and Freedom were difficult. Tucker more so because he was in a REALLY thick shell, but he wasn’t nearly so bound. At first I thought it was his big pincher that was holding him captive. Well, it was, but in actuality, it was EVERY leg that was stuck. The two on his left were absolutely super glued to the shell, the two on his right were so cramped they were not visible. His little pincher was no where to be seen. It was squished under him and one of his left legs was over the top of the other one. completely unnatural. It’s like crossing your legs and having your body roped to your legs with your arms squished and crossed, somewhere in the middle.
Probably about an hour in, maybe more.
This is about an hour and a half into it.
This I will never forget. I stabbed him. you can see his on his right leg. as soon as I did it, he kicked his leg out in pain, and all my apologies to him didn’t help. soon it went soft and limp. ugh. I am always SO careful when I do this. I have to chip the shell away flake by flake by flake. once in a while I can get a ‘chunk’ and it will go zinging through the air and hit a wall. the chunk is the size of a pencil lead tip. anyway, about twenty minutes after I stabbed him, he kicked his leg out again and wouldn’t put it back down. I knew if he survived he would drop it, at least they have that benefit of dropping a leg if need be. it was soft and cold. guilt=piccalo.
It’s hard to tell, but this pic shows how much he was cemented. A few times I just set him down on the towel and hoped he would just die. but I started clipping away more and more and finally I could see his eyes. sort of. but he saw me and I couldn’t stop now.
painted shells should be outlawed. period.
so, after seeing his eyes, I knew the worst was to come. if I could stab his leg so easily, damaging his eyes would have been catastrophic. and it just so happened that the worst part of where he was stuck was precariously close to his eyes. so I used stress coat as lube and flake by flake by flake his legs started moving. I couldn’t take pics at this point because I was too close. I thought. he was SO bound, that once he started getting a little room to move, his leg lifted a little so it was over the surface of the shell. kinda like a rubber band tight on your finger. I was hoping he’d start to move himself out but he did not move whatsoever. I honestly didn’t think i’d get him out.
FINALLY finally finally 2.45 hours into it, I saw an eye, and only one eye because he still couldn’t move, but one last clip did it and he moved so I could see both eyes. and a pile of cottage cheesy scum on his back. I don’t know what it is, but I THINK it was a collection of shell flakes/stress coat/water. poor thing.
i put him in the shell box and off went his leg and he went to the side, I missed all of that, in the 2.2 seconds I turned away.
this is booger. with the paint blob booger on her stupid shell. most of her legs are broken, but she’s otherwise cute.
so in they go to the iso tank. I checked on them 10 minutes later and houston we have a shell change.
i saw his old shell sitting there and omg. lifted the cocohut and there he was.
her name is booger.
HOUSTON WE HAVE A SHELL CHANGE. he needs a name.
i hate to do it but I always take pics of them next to their stupid old shell.
and sadly, he *feelerfeeler*d it, smelling it. it has to be like a nightmare.
the million flakes from rinsing the nipperthingies. they were all over the kitchen and me.
too bad her shell sucks, because the color is great with her color.
see that blob of crap? tell me why painting a seashell is necessary.
Get the odor out of shells? I know to boil newly purchased shells, but I want to reuse some of the shells that are smelly from a crab dying in it. So far, we’ve lost one of the Littles (PP = Faith) and I think another is not going to make it. I have her in iso and will wait til we are sure before dealing with it’s shell tho. But I tried soaking the ones that Violet and Faith were in because the odor was so strong in them yet and then boiled them. I remember reading how Vinegar can damage them so I didn’t use anything but declorinated water. Didn’t dare try soap or dishwashing liquid either. But once the water got to boiling the odor nearly drove us all out of the house. :sick: What should I have done? Is there a safe way to remove the odor?
I really want to get these shells clean because they are both usable shells. Violet’s was large and not particularly pretty on the outside, but the inside is in good condition except for the odor. Faith’s is painted and boiling removed most of the paint and the clear shellac or what ever the polish was on it. The size of that one is perfect for the other Little one and since I don’t have much in the way of tiny shells (waiting for a new order to get here), I really need it before she comes up from destressing. At least I HOPE that is why she is still in hiding…
are you boiling with SALT water?
I just had a crazy thought that might safely work….ocean water will probably eat away the shine of the shell if there is any. But put some ocean water within the shell and leave it sit for a couple of hours. Shake out the ocean water, and here is the crazy part…put it in a baggy with a twisty tie on it and place it in the freezer overnight. Not sure if you have ever heard of it or tried it, (and it works too….if one has a smelly pair of tenny shoes, (or any shoes) and put them in a garbage bag and put them in the freezer for 24 hours it kills the stench of the shoes. Honest…it works with shoes.
Hmmm… Hadn’t thought of using salt in the water. Just declorinated and boiled about 5 minutes. I was tempted to try a weak bleach solution but was afraid of what that might do to the shell and didn’t want to risk not being able to get it all out of the shell. I would think that a crab with a bleached bottom would be crabby indeed. :blush:
I like the baking soda and/or lemon idea as they are natural and are natural deodorizers. Faith’s shell is a shiny spotted one (looks to be a Babylon Spirata type) so I’d like to preserve it if possible. Violet’s shell is a nonpolished Pica and the outside is sort of crusted with a stone like material that I was afraid would come off when it was cleaned – but it didn’t.
Marie. Oh golly – I remember doing that with tennies when I was a girl. It really did kill alot of odors – we soaked them in baking soda water, froze them in the snowbanks in winter and then left them hanging on a line for a day or two. I’ll give it a try with the soda and the freezer.
Ok – I wonder… How about soaking in Hydrogen Peroxide? Just in case the odor is still there because there is something still stuck inside the shell that I can’t get at. Wouldn’t that bubble it out?
I was a bit leery to post this link last night, but if you think something maybe stuck in the shell, (part of Violet or another previous critter) this maybe a route to try. But I would be very hesitant about any chemicals within the hermies shell. (one never knows if the shell will absorb them or not)
How to clean live seashells
It might be a good idea to check with local authorities where you will be gathering the sea shells as some areas prohibit the practice of collecting live specimens. If you are lucky enough to gather some live sea shells there are a few methods of cleaning that can be followed. Before starting to clean your live seashells you might also want to read through cleaning dead seashells.
1- Burying-This one is by far the easiest to do. Find an area in your yard where you don’t mind digging a hole and bury the seashells about 18 “( enough so animals will not dig them up). Let them remain buried until insects, larvae, worms, and bacteria remove all the tissue (a least a couple months). The longer the better. Go to step 5
2- Freezing- If number 1 is not an option then this method will work also. Place the seashells in a water tight bag and cover with water then place them in the freezer(just like you would fresh fish). When ready to clean allow the seashells to thaw at room temperature. After they are completely defrosted you should be able to grab hold of the animal inside and gently pull it out. Go to step 5
3- Boiling-Take a pot of water large enough to hold the seashells you are cleaning. Bring the water to a boil and let boil a few minutes(longer for larger or a great number of seashells). Using tongs and being careful not to burn yourself remove 1 shell and grasp with gloves or towel, so you don’t burn yourself, and gently pull out the animal tissue inside. Go to step 5
4-Microwave- This is an easy method if you don’t mind the smell in your microwave (my wife is not to fond of this method). The time you cook your seashells can really vary by microwave so really just try it until you figure out how long to put them in for and then treat them just like you would in step 3. Go to step 5
5-Bleaching-After no tissue remains soak the seashells in a 50-50 solution of bleach and water. There is no set time to let them soak because it various by the type of seashells and quantity of seashells being cleaned. Just make sure to remove them after the periostracum is gone. The periostracum is the flaky leathery covering that covers most live seashells.
6- Fresh water-Remove from bleach and rinse thoroughly with fresh water. If preferred you can rub the seashells with baby oil to give them a luster.
Notes of interest
1- If tissue should break off inside the seashells you are cleaning there are two ways to proceed. Shake the seashell vigorously trying to remove the extra tissue or sit it outside where flies, bugs and ants will crawl inside the seashells and remove any remaining tissue.
2-Operculums- This is the trap door of the shell that helps protect it from intruders. Many serious collectors like to keep this part of the shell to show that it was a live taken seashell
3- Water picks- Sometimes on smaller seashells another method to remove the tissue is to squirt them with a water pick and the high pressure will push the tissue out. This will only work with smaller seashells.
4- Dental picks- A lot of times dental picks and other instruments are used to help in removing barnacles and other growth on seashells. These can be purchased at many seashell stores. Try checking www.seashells.com .
MAKE SURE TO WEAR PROTECTIVE EYEWEAR WHEN CLEANING SEASHELLS
does the smell really need to be gotten rid of though? I mean, for us, yeah, of course it’s WAY more pleasant to have a clean, non smelling shell for our crab to inhabit, but for the crabs, they probably don’t care. I guess that there’s a smell there for a reason – i wonder if there is some little decomposing bits of the previous crab still left. If thats the case, they probably do need to be cleaned. I know i’ve cleaned (just boiled) some shells, other’s I’ve just placed back in the crabitat – the crabs don’t seem to care too much.
Normally if there is a stench to the shell that cannot boil away when sterilizing it there is ‘something’ down within it. So it is best to try to get the odor to go away. As you said though, it probably doesn’t bother the hermies as far as the smell goes…but if there is something down within the shell it could harm their soft abdomen. I have had this happen a couple of times with new shells I have bought online. They appeared fine, no odor, but when I boiled them prior to offering them to the hermies oh my goodness the stink! :sick: After a few boils, an ocean water soak and another boil, not sure what it was but upon shaking the shell small bits of black substance came out of them. On one shell I had to do the ocean water soak a couple times and boil again after each soak before the stink went away and each time something black came out of the shell. :sick:
P.S. Sorry to say to, but this ‘might’ of been one of Violets complications too?
i guess that’s probably a pretty good rule to follow – if it smells, there’s something causing the smell and it’s best to get it out
Perhaps I’m just stupid and didn’t know this, but, I had a shell that needed cleaning. It had some funky green spots inside that I’m thinking had something to do with when my hermit crab, Daes, who was occupying the shell died. I didn’t want to use bleach on the shell to get those spots out and I wasn’t sure boiling water would be helpful. I guess I should’ve tried vinegar first, but nope. I decided I’d try lemon juice. I left it sitting overnight and this morning I dumped out the juice. The shell it self was crusty (strange) and that could’ve been scrubbed off. BUT …the lemon juice ate a hole through the shell.
So, the conclusion? Do not soak your shells in lemon juice to clean them. At least overnight.
And the worse part? It didn’t even get rid of the green spots!
So I thought I’d just post this and save everyone a shell.
I have alot of natural shells that i just love, but have recently (i know i am a bit of a blonde;;lol) relized that my shells are the same as all of the pretty ones i like they just are’nt buffed out. does anyone know of a fast and easy way to buff, polish them? I had ordered a black pica from Vicki and have relized that i have severel of the same kind of course the one i got from her was so much prettier so i got my nail files out and decided to file away on one and sure enough after 4 hourse and three blisters in now looks the same! I would really like to do this with all of my shells.
I have a bunch of pica shells I got from a pet store that had bleached them, so the crusty stuff clinging to them are all white. When I got these, I was wondering the same thing….how to get that stuff off. Hunter actually changed into one of them, but even though his abdomen is large the shell seems to be too heavy for him to lift properly and comfortably. The front of the shell rests right behind his eye stalks (peepers, I call them) when he walks. Now, he’s back in his old shell. Maybe if I buff the shell a bit it will lose alittle weight Confused So, Rachel, you used a nail file
lol i did! it really did do what i was wanting but wow that was some work involved. humm. maybe one of those rock tumbler things would work?
I’m in the process of using my dremel tool to take off some of the outer layer of some goldmouth turbo’s I have so they are more lightweight. Its a process! I’ve been using really coarse sanding wheels and after about four hours worth I’m kinda sick of it lol. There are lots of different bits for dremels so I’m sure it could be done with one of those minus the blisters lol.
ha ha where do i get something like that?
I wonder if one of those foot pedicure devices would work. The hand held thing with the spinning, gritty knob.
Or….wonder how much a jeweler would charge? LOL, yeah right!!
But seriously, I wonder if the above would work?
My hubby got me the dremel for $20 at walmart. Its a little cordless model and I absolutely love it lol. There was also a wide selection of bits there with the dremels but since he has TONS of bits I just use his lol.
LOL Not to go too off topic, but does any one have an idiot proof guide to using the Dremel? I have a new one that I’ve never used because I couldnt figure out how to get all the different tips onto it. I have wanted to hollow out/lighten some of my shells for some experiments, and I cant figure out how!
Ahhh you guys the dremel is an awesome tool! So many uses!!! jsrtist..your dremel came with a little wrench looking thing..use it to loosen the silver part where your bits go into, swap bits and tighten back up. (PS there should be a little button on the grip that you have to push in while you do this) Read the manual it should show you. Once you get the hang of it you will come up with endless things to use it on.
I wonder if one of the stone grinding bits would be better than a sanding one for shells?
Lol I absolutely love mine! Hubby has one of his own and I always wanted to use it so he surprized me with a smaller one of my own. His is pretty neat because of all the different attachments you can use, and its variable speed but I do just fine with my cordless little one that has hi and low speeds.
I’m planning on going to the hobby store when I get paid to check out some of the heavy duty craft bits they have there. So excited
A hermit crab’s shell is his home and his protection from predators and dessication. Hermit crabs take up residence in discarded shells and can not make their own shell.
Hermit crab’s should be allowed to choose the shell they prefer from a selection of different sizes and types of shells. Natural shells are the best option. Painted shells should be avoided. Shells should not have jagged edges or holes in them.
Most species of hermit crabs will prefer a shell with a round opening. Coenobita compressus (Ecquadorian) prefers a shell with a D shaped opening.
Shells should be cleaned and boiled before offering to your hermit crabs. If you collected shells from the beach be sure the shells are EMPTY before bringing them home.
Hermit crabs can be very stubborn about changing shells but do not attempt to force a crab from it’s shell.
Contrary to common belief, a molt does not mandate a shell change! If the existing shell is roomy enough to allow for growth during a molt, the hermit crab may feel no need to change shells. Additionally, you will find some hermit crabs are chronic shell shoppers, always trying on something new.
Photos of common hermit crab shells:
[url=http://www.crabstreetjournalphotos.com/thumbnails.php?album=114]CSJ Seashell Photo Album[/url]
[url=http://crabstreetjournal.com/xoops/modules/news/article.php?storyid=68]Are hermit crabs looking for lighter and larger shells?[/url]
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