E-mail to distributor

Archived information regarding hermit crab welfare work done online, in pet stores and in the wild. Also discussions about the larger ramifications of keeping crabs as pets, captive breeding, etc.
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JediMasterThrash
Jedi Tech Support
Jedi Tech Support
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Joined: Sun Jan 11, 2004 3:05 pm
Location: Nerima district of Tokyo, Japan

E-mail to distributor

Post by JediMasterThrash » Tue Dec 05, 2006 6:40 am

Somehow the original thread got lost, so I'm reposting one of my responses for archival purposes. This thread started when someone sent an e-mail to the seashellshop, and got a closed-minded response back that accused all of us (ALL of us on-line crabbers) of just making stuff up about hermit crabs.Oh, and of extra amusement was his complete insistence that caribbean islands have 0% relative humidity in the winter...So I wasted a whole evening the other day and compiled all the facts into a 4-page e-mail. Some of the info on molting was taken from the Crabbage Patch, since she did a great job of summarizing the research articles. Unfortunately, I didn't want to list her page in the citations because he apparently doesn't hold internet crab sites in value. So I just included original sources of the research, plus other sources of research I used.Hello....I did some introduction to try to start off on a positive, agreeable note so that he might actually read the rest of the e-mail rather than just throw it away...Beliefs in crab care in the community have been changing rapidly, and I am always actively searching for new ideas and new facts, and not afraid to change old beliefs. Since I joined 3 years ago, over half of the care beliefs of the time have been reversed or amended. I have no problems with the leash, and understand that most metal ions are not harmful to crabs.However, I wasn't too appreciative of the accusation that we all just make stuff up. While it is true that a lot of it is observation, there is a lot based on fact as well.In particular, there is biological research on Anomura, Coenobita, Shrimps, crabs, and other Crustacea. A list of reference is provided at the bottom of this e-mail. In particular, the Greenaway article on Terrestrial adaptations in the Anomura and the De Wilde article on the Ecology of Coenobita Clypeatus.As the subject states, I wish to discuss the molting process in hermit crabs, for reasons that will become evident.Hermit crabs need to molt every month (teenies) to every 1.5 years (jumbos). At this time (the Proecdysis stage), crabs will spend a lot of time by the water dish and will build up a supply of water and minerals in a molt sac on the left underside of the abdomen. Crabs also need salt water, as the correct water, salts, and nutrient balance is used to create the Hydrostatic pressure necessary to crack the exoskeleton.However, crabs require a damp, environmentally isolated, secure place to molt. Hermit crabs have a molting-defense mechanism in the form of a hormone. Xanthurenic acid is a molt-inhibiting hormone that is created in the eyestalks. Crabs multi-faceted eyes are keen to light and motion. Seeing light, activity, and other crabs causes them to secrete the molt-inhibiting hormone so that they can postpone molting until the conditions are correct for it. The correct conditions are simply a damp, diggable substrate at least twice as deep as the crab, where the crab will bury. The dark seclusion allows them to release the Ecdysone hormone to start the molting process (Ecdysis stage). The shelter of the substrate keeps the humidity and temperature stable for them, and the dampness of the substrate is necessary in order to tunnel into it and create the underground shelter. The hydrostatic pressure from the water bursts the exo, and then they can withdraw from it, and spend the next 2 weeks to 2 months buried while their new exo hardens (the Metecdysis stage).So, what happens if they never encounter proper molting conditions? The molt-inhibiting hormone continues to build up until one of two things happens. In small crabs, they can force a molt (known as a surface-molt) and sometimes survive. Larger crabs rarely survive a surface molt. In most cases, the hormone builds to toxic levels until it reaches a point where the crab can either not molt anymore and dies, or will force a molt and not survive. This unfortunately is what happens to crabs that are kept too long in cages that have no substrate or just aquarium gravel (which they cannot properly dig and bury into). Beach sand and earth (their natural environments) are best, while masonry and play sand are the next best, along with dirt (that has never been exposed to pesticides or fertilizers) and coco-fiber.Next, I would like to talk about heavy-metal ions. Not all metal ions are toxic or carcinogenic, however a select few heavy-metal ions are known to be (sources included below), and include Cr (cromium), Ni (nickel), As (arsenic), and Cd (cadmium). Most good tap-water conditioners, like Aqua-safe, remove these heavy-metal ions from water, along with chlorine and chloramines, both of which are also toxic to crabs. Just leaving water out overnight will only remove the chlorine. It will not remove chloramines, because it is a more stable compound (chlorine combined with ammonia), and a lot of water treatment plants are using it more. They are using it exactly for the reason that it doesn't dissipate from the water like chlorine does, but that's what causes our problem. Letting the water sit will also not remove the above mentioned heavy-metal ions, so using a true water conditioner is necessary. Also, somewhat related, saltwater is slightly corrosive and will cause metal it is in contact with to rust.Also, on the salt water, hermit crabs undergo the process of Osmoregulation. This means that they auto-regulate the salinity of their internal and shell water. We can't always provide the exact balance the need in a single water dish, but by providing both a fresh and salt water dish, the crabs take what they need from each. The main osmoregulatory means is flushing the shell resevoir with seawater either by immersion or drinking to replace fluid losses and facilitate loss of salt from body fluids. They also maintain a minimum concentration in they're "blood" (Hymolymph) similar to that of seawater. Even though C. clypeatus lives farther inland, and requires a more dilute concentration of saltwater than C. compressus, they still require some amount (though some can be obtained from salts in food, as long as it's non-iodized).Finally, I wish to talk about the modified gills. They are located between the 4th and 5th periopods and must be kept moist to function. Glands are used to keep them moist; however, if relative humidity is low, the moisture will evaporate faster than it can be supplied. Also, if water sources are scarce so they cannot keep shell water supply up (which helps prevent extra evaporation and salt loss) they won't be able to keep the gills moist. Once the gills dry out, permanent damage can occur, which may result in imminent death over the next month.So, what is relative humidity? Relative humidity is the percent of saturation humidity. If the rel. hum. is at 100%, that means that the air cannot hold any more water. This means that water in contact with the air will not evaporate (which can lead to heat stroke in humans because our sweat won't evaporate to cool us down). If rel. hum. is lower, then the air can hold more moisture, and water will evaporate more quickly. This is why relative humidity is important to hermit crabs. If it is too low, the gill moisture will evaporate faster than they can produce it, which can over time lead to gill damage. It will also evaporate their shell water reservoir faster, and will dry out the moist substrate faster (and the moist substrate is needed to burying to molt).Relative humidity can simply never reach 0% near the ocean, because by definition, the air is "empty" of moisture and water will evaporate quickly from the ocean to fill the void (simple laws of thermodynamics). In the winter, when air cools, the water vapor saturation point lowers, so for a given amount of actual water vapor in the air, the relative humidity actually increases.In fact, here's a page from the Florid Division of Forestry that shows the current relative humidity in Florida. As you can see, half o the state is in the

70-80% range at this moment, even inland.http://flame.fl-dof.com/fire_weather/ob ... rh.htmlAnd also, in fact, here's a Department of Natural Resources page that shows the average relative humidity for Florida over the course of several years for several cities.http://www.dnr.sc.gov/climate/sercc/cli ... grh.htmlAs you can see, even in the dead of winter, the humidity is still in the 80% range in the morning and 50-60% in the afternoon (as I mentioned before, as temperature increases, the relative humidity will decrease since it can hold more water).The question I hope you will care about, is why has this crabbing community come together by the thousands, and worked to create these care recommendations based on anecdotal evidence and observation? The reason is simple. 95% of us came to this site because we bought hermit crabs, and they died. They obtained crabs and followed the "care" from books and pet store brochures, and the crabs died within a few months to a year. The average lifespan of a crab kept by someone using care and kritter-keepers from the pet store/mall kiosk is about 6 months. This happens to correspond with the time a captive crab will need to have its first molt. Simply put, the crabs are not surviving their first molts because they are unable to properly molt. You can poll the community of 1000 members to confirm this, since most of us were these people until we came together. We learned methods to try to emulate their natural environments, and experimented with many different crabitat conditions and care. This experimentation IS science. We theorize what we can do to improve their conditions, then we experiment with it, observe the results, and report our findings to the community. This is the scientific method in action. Under our new care guidelines, the average lifespan of crabs has increased to 3-5 years in captivity from the 6-months using pet-store care.You simply cannot deny the facts, because 10s of thousands of hermit crabs are dying in captivity because something isn't right with their care and conditions. We know, because our community is filled with people who came together because we lost many crabs and wanted to know why, and what we could do to keep them alive. And that is why some of our zealous members try to contact pet store owners and pet distributors to help them improve conditions and care recommendations.Now, the one last thing I want to mention is the difference between your environment and ours. If you live in Florida, it is OK to let your crabs life in a cage outside, open to the environment, and they'll do fine, because that is their environment that they grew up in. However, when someone the great white north adopts a crab, it's a different story. The crabs can't survive in our environment because it's too different from the Caribbean area. We need to properly emulate their natural environment, and that's where new care ideas come in.Thanks,Ash.Greenaway, P. 2003. Terrestrial adaptations in the Anomura (Crustacea: Decapoda). In: Lemaitre, R., and Tudge, C.C. (eds), Biology of the Anomura. Proceedings of a symposium at the Fifth International Crustacean Congress, Melbourne, Australia, 9-13 July 2001. Memoirs of Museum Victoria 60(1): 13-26.De Wilde, P.A.W.J. 1973. On the ecology of Coenobita clypeatus in Curacao with reference to reproduction, water economy and osmoregulation in terrestrial hermit crabs.Stud. Fauna Curacao 44: 1-138.,Bliss, D. E. 1982. Shrimps Lobsters and Crabs Their Fascinating Life StoryNew Century Publishers, Inc., New Jersey.Warner, G.F. 1977. The biology of crabs. Van Nostrad Reinhold Co., New York.Burggren, W.W., and B.R. McMahon, editors 1988. Biology of the Land Crabs. Cambridge University Press, New York.PI: Michael Karin, University of California, San DiegoInteractions of Heavy Metal Ions with the Human Genomehttp://www.epa.gov/Region9/water/chloramine.htmlEndogenous xanthurenic acid as a regulator of the crustacean molt cycleY. Naya*, W. Miki, M. Ohnishi, M. Jkeda and K. NakanishiSuntory Institute for Bioorganic Research (SUNBOR): Wakayamadai, Mshima-gun, Osaka618, Japan
JMT.

Stuck-up, half-witted, scruffy-looking crab-herder since '92.

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