# Dart Frogs and Crabs?



## tdileo (Jul 25, 2017)

Hi everyone. I want to start by saying I'm not new to frogs, but I am new to dart frogs. And I have been on 5 year break from frogs. I'm now 15 but in the past I had whites frogs, a cuban tree frog, a pair of american toads, and a grey tree frog. They all lived for quite a few years but I eventually gave them away because I had moved onto aquariums. But back to the frogs. 
I have a 20 long laying around. Due to my reef tank I've become a really big crab person and I've fallen in love with vampire crabs and while designing a tank for them I learned they have very similar requirements to dart frogs! Which of course tossed me into the world of these beautiful creatures. Now my biggest question is are there ANY species of crabs I can keep with dart frogs? I know just about everybody is against mixing species and I am aware vampire crabs are from southeast asia while lots of dart frogs are from south america. But I'm just curious if there are other species of semi-aquatic crab I could keep with dart frogs. 


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## S2G (Jul 5, 2016)

http://www.dendroboard.com/forum/beginner-discussion/281073-dart-frogs-vampire-crabe.html

https://m.youtube.com/watch?feature=youtu.be&v=-oBka94-APA

Bad idea. Too small of a tank for a water feature much less mixing an opportunistic animal like a crab. I'm 100% positive a vampire will kill a dart.


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## Entomologist210 (Apr 24, 2014)

Very bad idea. Organisms across the globe can fill very similar niches (like the darts and crabs), but they are separated by geography and evolve within separate ecosystems. For example, both Indian Bengal Tigers and North American Grey Wolves have the same habitat requirements, but you wouldn't put them in the same forest because one species would out-compete the other for resources or even predate on the other leading to a local extinction. This situation is exasperated when one species, which has evolved unique defenses or offensive abilities outside a local ecosystem, is suddenly mixed with an ecosystem whose own defenses and offensive abilities are trending towards local defenses and offensive abilities. The invader has free reign to cause havoc. We call these organisms "invasive species" and as a reefer, I'm sure you're familiar with the damage that can be caused with them learning about fishes like the Lion Fish. I recommend the book "Ecology" by Cain and Bowman. You're at the right age where that information can really help you out when designing future vivaria of all kinds.


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## Woodswalker (Dec 26, 2014)

Here's something to consider. A crab's every appendage is effectively a small knife, and they are even equipped with shears. A dart frog, on the other hand, has a delicate membrane covering its entire body, and not much in the way of teeth, either. 

Both are predators seeking the same prey in the tank, and both occupy overlapping niches. They would be in direct competition with one another, and given their physiologies, it's not difficult to predict the winner of any potential confrontation. Furthermore, vampire crabs have a reputation as aggressive feeders. They tear their prey apart, and it's important to keep in mind that they will eat a wide variety of food.

Fortunately, they seem to do well in relatively small tanks, and if you're doing a lot of research on frogs, you should be able to care for the crabs using a very similar approach. Keeping them separately, you can enjoy both without worry.


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## tdileo (Jul 25, 2017)

S2G said:


> http://www.dendroboard.com/forum/beginner-discussion/281073-dart-frogs-vampire-crabe.html
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Vampire crabs don't need a very large water area so I was going to create a small stream to a pond about 1 and half inches deep. I know how opportunistic crabs are since I've witnessed emerald crabs eating corals in my reef tank. But in my experience if you keep them well fed there isn't an issue. From what I've seen vampire crabs are rather shy and while they are aggressive feeders, I'm not too sure they would go after frogs that are bigger or the same size as them. 


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## tdileo (Jul 25, 2017)

Entomologist210 said:


> Very bad idea. Organisms across the globe can fill very similar niches (like the darts and crabs), but they are separated by geography and evolve within separate ecosystems. For example, both Indian Bengal Tigers and North American Grey Wolves have the same habitat requirements, but you wouldn't put them in the same forest because one species would out-compete the other for resources or even predate on the other leading to a local extinction. This situation is exasperated when one species, which has evolved unique defenses or offensive abilities outside a local ecosystem, is suddenly mixed with an ecosystem whose own defenses and offensive abilities are trending towards local defenses and offensive abilities. The invader has free reign to cause havoc. We call these organisms "invasive species" and as a reefer, I'm sure you're familiar with the damage that can be caused with them learning about fishes like the Lion Fish. I recommend the book "Ecology" by Cain and Bowman. You're at the right age where that information can really help you out when designing future vivaria of all kinds.




I am completely aware of the geographical differences and thats why I wanted to see if anyone had done it before. I do know that there are small semi-terrestrial crabs in the same area as a lot of the dart frogs are found so if I ended up doing a pair of leucos I could also keep a single crab species that also comes from the same area. I very much appreciate your replies 


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## tdileo (Jul 25, 2017)

Woodswalker said:


> Here's something to consider. A crab's every appendage is effectively a small knife, and they are even equipped with shears. A dart frog, on the other hand, has a delicate membrane covering its entire body, and not much in the way of teeth, either.
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I would optimally have two 20 longs, one for a trio of Leucos and one for 5 or so vampire crabs. However I'm only allowed to keep my animals in my bedroom so at this point I've run out of space. And outlets lol. That was the main reason I wanted to attempt to keep them together. 


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## serial hobbiest (Mar 5, 2017)

tdileo said:


> I do know that there are small semi-terrestrial crabs in the same area as a lot of the dart frogs are found...


Sure... there's also a lot of snakes... doesn't mean they're compatible.


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## tdileo (Jul 25, 2017)

serial hobbiest said:


> Sure... there's also a lot of snakes... doesn't mean they're compatible.




There's a big difference between an inch wide crab and a snake multiple feet long. Please stay on the topic of frogs and possibly compatible crab species. I'm not looking for a stupid argument, I'm looking for information. If similar species like fiddler crabs (even though they should be in brackish water) are kept with african dwarf frogs I don't understand why a dart frog couldn't be with a small crab species. I'm not stupid and will not put animals in harms way by combining incompatible species but I am trying to gain a better understanding of how two very different creatures would behave towards eachother in an enclosed enviroment. 


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## Entomologist210 (Apr 24, 2014)

Honestly they can coexist... in a sufficiently large enough enclosure. The problem is that such an enclosure would have to be VERY large, as in small pond large. It would have to also include a large selection of other organisms both intra and extra-guild, a wide selection of prey items, micro and macro-fauna to sustain those prey items, as well as enough space for avenues of escape and congregation. Google the Competitive Exclusion Principle and Georgii Gause's experiments with paramecium. Then google Huffaker's mite experiment. Ecology is awesome, though Entomology is better.


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## tdileo (Jul 25, 2017)

Entomologist210 said:


> Honestly they can coexist... in a sufficiently large enough enclosure. The problem is that such an enclosure would have to be VERY large, as in small pond large. It would have to also include a large selection of other organisms both intra and extra-guild, a wide selection of prey items, micro and macro-fauna to sustain those prey items, as well as enough space for avenues of escape and congregation. Google the Competitive Exclusion Principle and Georgii Gause's experiments with paramecium. Then google Huffaker's mite experiment. Ecology is awesome, though Entomology is better.




Thank you for a legitimate answer. This is the type of reply I was looking for and I think a lot of others with similar questions would be much happier hearing this than "you're an idiot and should never try that, go ahead and add an alligator while you're at it". 
So now I will either go with dart frogs OR the crabs. I was thinking of a trio of leucos, but would honestly prefer another species that I could have 4 or 5 of, perhaps maybe only an inch or so long? If you have a reccomendation for one let me know please 


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## kimcmich (Jan 17, 2016)

tdileo,

Mixing frogs and crabs is risky for both animals. Many frogs do coexist with terrestrial crab species in their native habitat. But coexisting populations only coexist _on average_ - that doesn't mean individual crabs and frogs don't have injurious or even deadly interactions with each other. These kinds of bad interactions would only be increased if the animals are confined to a couple of square feet inside a glass box in someone's bedroom.
You might indeed be able to keep carbs and frogs together - but this will depend very much on the individual "personalities" of the crabs and frogs. If you get an especially aggressive crab or an especially oblivious frog (neither of these tendencies will be easy to discern until you put them together), crabs will start killing frogs. If you go with a larger frog species, some frogs may try to attack the crabs injuring both in the process.
Finally, I think you will miss out on reproductive behavior if you mix these two species. Frogs would eat baby vampire crabs -and vampire crabs of all sizes would eat frog eggs. (I think the stress and competition of having each other as tank mates would also discourage reproduction.)
I see where you are coming from: One tank filled with brightly colored crabs and frogs sounds awesome. It will probably not be good for the crabs and frogs involved, however...


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## tdileo (Jul 25, 2017)

kimcmich said:


> tdileo,
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Thank you as well for a very good answer. As a reefer I've experienced this and completely know what you mean but on a different scale. Some angelfish will eat corals, some will only eat hard corals, and some won't eat any at all. It all depends on the species. And I definitely have seen this with crabs. I've had some so friendly I could pick them up and hold them, others that hold onto the rock so tight that if I pull with so much strength I get worried I will break their legs keep staying, and others that go after your hands in the water. The reproductive behavior doesn't bother me because I would rather not deal with rehoming babies of either species but I would not want my animals in a stressful enviroment.


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## Ed (Sep 19, 2004)

tdileo said:


> Vampire crabs don't need a very large water area so I was going to create a small stream to a pond about 1 and half inches deep. I know how opportunistic crabs are since I've witnessed emerald crabs eating corals in my reef tank. But in my experience if you keep them well fed there isn't an issue. From what I've seen vampire crabs are rather shy and while they are aggressive feeders, I'm not too sure they would go after frogs that are bigger or the same size as them.
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> Sent from my iPhone using Tapatalk


There are reports of them capturing and eating crickets of the same body size of the crabs (not just adult crabs) so I wouldn't underestimate their ability to capture prey items. 

Using fiddler crabs as an example isn't a great comparison, as fiddler crabs are considered deposit feeders a totally separate type of feeding behavior than that of Geosesarma (although some male Pacific fiddler crabs are known to kill and eat other fiddler crabs). (see for example McLain, Denson K., Ann E. Pratt, and Allison S. Berry. "Predation by red-jointed fiddler crabs on congeners: interaction between body size and positive allometry of the sexually selected claw." Behavioral Ecology 14.5 (2003): 741-747.). The risk of predation posed by the two types of crabs is very different. 

some comments 

Ed


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## Scott (Feb 17, 2004)

Summation.

"It seemed like a good idea at the time."

s


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## Pumilo (Sep 4, 2010)

If you just keep slutty girl frogs out of your vivarium, you shouldn't have problems with dart frogs with crabs.


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## tdileo (Jul 25, 2017)

Pumilo said:


> If you just keep slutty girl frogs out of your vivarium, you shouldn't have problems with dart frogs with crabs.




It took me a good minute to get this lol. At first I thought you meant because female frogs are usually more aggressive and then I realized what you actually meant haha


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## serial hobbiest (Mar 5, 2017)

tdileo said:


> There's a big difference between an inch wide crab and a snake multiple feet long. Please stay on the topic of frogs and possibly compatible crab species. I'm not looking for a stupid argument, I'm looking for information.


I wasn't giving you a stupid argument sir, but a point of consideration, because you were just rationalizing that since crabs and frogs can come from the same environment, that perhaps they can be housed together. *I used snakes as an example to illustrate your erroneous reasoning so that you don't use such reasoning & make a mistake.* I honestly didn't mean to come off offensively. It's not a comment that I would take any offense to, and I don't see why you seem to.



> I'm not stupid and will not put animals in harms way by combining incompatible species


Obviously, and I never implied you were stupid. 



tdileo said:


> Thank you for a legitimate answer. This is the type of reply I was looking for and I think a lot of others with similar questions would be much happier hearing this than "you're an idiot and should never try that, go ahead and add an alligator while you're at it".


Who said that? You're taking offense where none was given, and nobody here has suggested you go ahead and throw in an alligator or any other harmful species. I'll admit I'm not of much help on this topic, but I'll stand by what I said, as it was in effort of being _some_ help, and I certainly didn't deserve the effort on your behalf to dishonestly disparage me.
Sorry we got off to such a rocky start, but please do try to watch the knee-jerking. I'm not bad guy, okay?


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## tdileo (Jul 25, 2017)

serial hobbiest said:


> I wasn't giving you a stupid argument sir, but a point of consideration, because you were just rationalizing that since crabs and frogs can come from the same environment, that perhaps they can be housed together. *I used snakes as an example to illustrate your erroneous reasoning so that you don't use such reasoning & make a mistake.* I honestly didn't mean to come off offensively. It's not a comment that I would take any offense to, and I don't see why you seem to.
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Oh no for the last part I wasn't saying that you or anybody in this thread had seen it. But I've definitely seen some smart ass answers before and "get an alligator" and "just put in a fer-de-lance too" have been seen by me lol


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## Ed (Sep 19, 2004)

tdileo said:


> There's a big difference between an inch wide crab and a snake multiple feet long.


Actually the size of the snake can be a reason for the snake to ignore the frogs... many animals choose prey that is in a certain size range as too small of a food item won't recover the calories expended in capture attempts along with the mechanical problems in capturing and actually swallowing it. In this respect, larger snakes are often safer than smaller snakes as many of them also undergo ontogenic changes in prey selection. 

I should also note that there is a second flaw in the argument about the crabs as the frogs in the wild can be protected from attacks by arthropods due to their toxin profiles, which are lost in captive bred and even long-term captive animals. See for example 

http://ralphsaporito.weebly.com/upl...tor_defense_between_lifestages_in_pumilio.pdf

Murray, Erin M., et al. "Arthropod predation in a dendrobatid poison frog: does frog life stage matter?." Zoology 119.3 (2016): 169-174.



tdileo said:


> If similar species like fiddler crabs (even though they should be in brackish water) are kept with african dwarf frogs


I wanted to address a second point here and that is the comment about fiddler crabs and brackish water, the vast majority of fiddler crabs should not be kept in fresh or brackish water but sea water. The reason I wanted to address this is that this is an example of shoving animals into improperly setup enclosures, which should always be a red flag of improper attitudes to the welfare of the animals. 


some comments 

Ed


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## tdileo (Jul 25, 2017)

Ed said:


> Actually the size of the snake can be a reason for the snake to ignore the frogs... many animals choose prey that is in a certain size range as too small of a food item won't recover the calories expended in capture attempts along with the mechanical problems in capturing and actually swallowing it. In this respect, larger snakes are often safer than smaller snakes as many of them also undergo ontogenic changes in prey selection.
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I've never heard of keeping fiddler crabs in marine salinity. They can be found on the ocean but usually the ones found in the pet trade are collected from brackish areas.


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## kimcmich (Jan 17, 2016)

I was going to push back against Ed's statement, too. I have raised fiddler crabs from the ~1cm size to full adults in only _slightly_ brackish setups. These crabs were collected near the top of Mobile Bay in an area that fluctuates between 0% and 75% normal seawater salinity - with the low end of that range predominating because of freshwater outflow from the delta that feeds the bay. (As a side note, the inflow of seawater is further attenuated by the _single_ daily tide which is a quirk of the Gulf of Mexico).

I think Ed is correct to say that only some fiddler crabs species come from such low-salinity habitats - and the average pet store might not be especially careful about where it sources its stock. (Unfortunately, the more colorful species in the trade seem to be from more saline environments...)

Ed is also correct, however, in the sense that a full fiddler crab lifecycle cannot occur without seawater. Females release their eggs on the outgoing tide and the larval stage requires marine salinity.

Fiddler crabs are wonderful subjects - but they require a very specially constructed enclosure to handle their prodigious burrowing. Apart from that, however, they are easy to keep and fascinating to observe (the claw dance never gets old!)


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## S2G (Jul 5, 2016)

kimcmich said:


> I was going to push back against Ed's statement, too. I have raised fiddler crabs from the ~1cm size to full adults in only _slightly_ brackish setups. These crabs were collected near the top of Mobile Bay in an area that fluctuates between 0% and 75% normal seawater salinity - with the low end of that range predominating because of freshwater outflow from the delta that feeds the bay. (As a side note, the inflow of seawater is further attenuated by the _single_ daily tide which is a quirk of the Gulf of Mexico).
> 
> I think Ed is correct to say that only some fiddler crabs species come from such low-salinity habitats - and the average pet store might not be especially careful about where it sources its stock. (Unfortunately, the more colorful species in the trade seem to be from more saline environments...)
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A quick google showed uca pugnax at 29ppt. Which is around 1.021-.022sg vs 1.026sg (35ppt) for reef.

Distribution of the Fiddler Crabs, Uca pugnax and Uca minax, in Relation to Salinity in Delaware Rivers on JSTOR


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## neuroticat (Jun 26, 2017)

I am not familiar with fiddler crabs that live in brackish waters. However, the sight of a mass carpet of fiddler crabs running along the shoreline during lowtide while exploring the various inlets and jetties of Northeastern Florida is not unfamiliar to me. 

The live bait and tackle shops in the area often keep hundreds or thousands of the fiddler crabs in large plastic pens filled with sand and water from the inlets pumping into the enclosures. I would assume they have quite some success at this method of maintaining and keeping the fiddler crabs alive; because the smell of hundreds of dead fiddler crabs rotting away in the summer heat would be quite horrid to say the least.

To determine suitability of these fiddler crabs as food items for certain stomatopods, I have taken a few measurements of the specific gravity of the same waters during different times of the day (differences in water temperature) as well as during differnt tides. If I recall correctly, the waters touching the shoreline where these crabs thrived and make their home averaged a specific gravity of 1.021 or so. Sometimes it would be higher, and sometimes it would be lower. 

For the short time I decided to use the fiddler crabs as supplemental food items for my stomatopods, they seemingly did very well in my sump as long as I provided some live rock that protruded from the water line and food for them to eat. The water's specific gravity in that tank was 1.026 and they fared well enough for the relatively short time they were inhabitants of my sump.


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## kimcmich (Jan 17, 2016)

@S2G,

The cited paper found Uca pugnax was the only fiddler in "high salinity" environments (21-29ppt) - but that the sympatric Uca minax was found in lower salinity (including freshwater) - with both "abundant" in salinities from 8-12ppt. Although Uca pugnax could be excluding U. minax from the high salinity environment, this evidence would also be consistent with U. minax _preferring_ brackish habitat (at least in non-larval stages).


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## Ed (Sep 19, 2004)

tdileo said:


> I've never heard of keeping fiddler crabs in marine salinity. They can be found on the ocean but usually the ones found in the pet trade are collected from brackish areas.


Based on?? Do you have a reference as to the species that show up commonly in the pet trade? 

The closest I can find to claim for identification that would show salinity requirements for crabs in the pet trade is a sort of vague reference in the ADW for Uca longisignalis which states that they are common in the pet trade. See ADW: Uca longisignalis: INFORMATION 

In this case they state that the crabs are tolerant of waters from 5 ppt to 35 ppt and that the larger individuals are found in the lower range. 35 ppt is basically the same as regular seawater and the fact that the largest animals of this species is found here should indicate that a salinity close to 35 ppt is closer to optimal than 5 ppt (as the smallest are found at 5 ppt) as the territoriality in these crabs is based on size. The largest crabs have the best territories...

Now one of the things missing in this discussion is the impact that the burrows have on the exposure to salinity... keep in mind that the depth of the burrow may actually put the crab into denser saltier water while water of a lower salinity is found at the surface (saltwater infiltration). An example of this is U. subcylindrica which despite being found as far as 35 km from tidal water is considered to be adapted to a wide variations in salinity content (including hypersaline), may not be as tolerant of freshwater as other species. See 
RABALAIS, NANCY N., and JAMES N. CAMERON. "PHYSIOLOGICAL AND MORPHOLOGICAL ADAPTATIONS OF ADULT UCA SUBCYLINDRICA TO SEMI-ARID ENVIRONMENTS'." 

I will admit to speaking more emotionally than my more normal mode on the freshwater portion but given the paucity of data, a conservative argument against low salinity as suitable should be considered. The fact that a species may tolerate a certain condition for a period of time doesn't mean that it should be acceptable as a practice for its care. 

some comments 

Ed


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## Ed (Sep 19, 2004)

kimcmich said:


> Ed is also correct, however, in the sense that a full fiddler crab lifecycle cannot occur without seawater. Females release their eggs on the outgoing tide and the larval stage requires marine salinity.
> 
> Fiddler crabs are wonderful subjects - but they require a very specially constructed enclosure to handle their prodigious burrowing. Apart from that, however, they are easy to keep and fascinating to observe (the claw dance never gets old!)


I let my emotions get in the way of my usual fact checking... I agree that I like watching fiddler crabs do their thing. Someday I'll set up a tidal tank for them. 
I went into a pet store one time and they had Mictyris ssp in a salt tank with no way to get out of the water... 

some comments 

Ed


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## tdileo (Jul 25, 2017)

I'm a person who loves learning new stuff and would like to know everything but this is legitimately bored me. There was no reason to type that much about an animal that was mentioned for one second lol


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## andfrogs (Apr 26, 2017)

I strongly disagree. I have little to no interest in the topic, yet enjoyed reading the previous exchanges and the constant desire to keep any species under ideal conditions. Even briefly mentioning a species and their incorrect care requirements contributes to future readers keeping them in less than ideal conditions. 

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## S2G (Jul 5, 2016)

tdileo said:


> I'm a person who loves learning new stuff and would like to know everything but this is legitimately bored me. There was no reason to type that much about an animal that was mentioned for one second lol
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> Sent from my iPhone using Tapatalk


Lacking maturity? (I'd be surprised if you had a DL). You could of saved yourself some boredom by doing a quick google/dendro search. I found at least 5-6 threads on this topic within a minute. All ended with the same answer. 

Word of the day: (for the person that loves learning)
Ignorance (Noun)
Lack of knowledge or information


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## Woodswalker (Dec 26, 2014)

Many people come here because of the detailed, scientific approach, and robust discussion of the species we keep, and which interest us. 

Anecdotally speaking, my tween-aged niece has a tendency to claim things are, "boring," when they present too much information for her to process (beyond her frame of reference or understanding). Perhaps 15 is still a bit young for this sort of discussion.


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