# Will isopods eat eggs?



## Feelin Froggy (May 12, 2011)

Just curious if isopods will eat frog eggs? I've noticed that they will eat their dead... Just curious if that's a concern??


----------



## Pumilo (Sep 4, 2010)

I have whites, grays, and giant oranges running around all my vivs and am getting great breeding with no problems. I imagine they may eat dead eggs but I have eggs developing to maturity with the parents transporting the tads. There are plenty of isos in there too.


----------



## Hornet (Sep 29, 2010)

Dont most darts lay their eggs in small pools of water like broms? If so they are perfectly safe from the iso's. Isos are crazy little buggers, i've seen them take down a like eurycantha nymph lol


----------



## Wallace Grover (Dec 6, 2009)

I think I heard someone say they will ONLY eat "bad" eggs...


----------



## motydesign (Feb 27, 2011)

Hornet said:


> Dont most darts lay their eggs in small pools of water like broms? If so they are perfectly safe from the iso's. Isos are crazy little buggers, i've seen them take down a like eurycantha nymph lol


no, tads are deposited in water, eggs usually on surfaces like brom leaves ,film canisters, ect


----------



## DARTGUY41 (Aug 13, 2011)

They will most likely only feed on the bad eggs. In my experience that is the case.


----------



## mattolsen (Feb 26, 2009)

I believe I might be having a problem with iso's eating my intermedius eggs. They usually produce like crazy but lately have seen a lot of egg gels without the eggs inside. Could this be some other bug? It just doesn't make sense to see gel left over with nothing inside with no tads to be found.


----------



## Pumilo (Sep 4, 2010)

Any chance you have 2 female Intermedius in there, Matt? Could be a female eating another females eggs.
Another possibility. I had a pair of Varadero that were laying gel spots but no eggs. I suspected that she was eggbound. I ended up losing the female.


----------



## KeroKero (Jun 13, 2004)

I've found isopods on eggs before, but they have never done damage to them. They were usually there for one of two reasons - the area the eggs were laid in was their usual hide out and they got stuck on the eggs, or there were debris and/or infertile eggs worth munching on. They left fertile eggs alone. Just like with eating fellow isopods - they waited for them to die and then cleaned up the mess.

Springtails are the same thing - you can get a serious boom of springs on eggs that are infertile and get a fungal bloom on them. I started adding springs to egg clutches in their incubation containers and it helped deal with fungus that was growing on eggs (rarely a major deal since they were sitting in tadpole tea, but the springs go to where the tadpole tea was not and kept them clean) and often they helped keep fungus from infertile/dead eggs from spreading to good ones nearby. Again not often an issue unless there were more infertile than fertile but with this method is was uncommon that I had to bother removing bad eggs.

Hornet - PDFs are biologically interesting due to their breeding habits of laying eggs outside of water and transporting their tads to isolated water pockets. Most PDFs don't interact with broms in the wild, and those that do are rarely dependent just on broms, and will use any water source with the right conditions to raise a tad. Always fun to find tads in trash... like pumilio and auratus raising tads in soda cans tossed on the side of a road.

I've not had any of the Isos we raise in this hobby do anything other than eat detritus. I'm sure there are other more predatory Isos, but those aren't the ones in our tanks!

MattOlsen - I suspect it's one of your PDFs eating the eggs - if it was much else you'd be able to see them in the act. It's well known in many PDFs as part of competition for egg laying spots and/or mates for egg eating and stomping to occur, and I've even had a female eat her OWN eggs regularly. Drove me bonkers and I never figured out why - it was just her and her male in the tank. I thought she was just laying gel until I caught her in the act.

Pumilio - I don't believe there is much evidence that PDFs really have eggbinding issues, this has only been proven in explosive seasonal breeders. Laying gel or eating the eggs just laid (like the frog I mention above) may be a sign of other issues that remain unknown until a necropsy is done. The female I mentioned stopped eating her eggs after a while and one of the theories was that she had some sort of nutritional deficiency and eating the eggs was an attempt to keep those nutrients in her system. Much like eating their skins allows them to retain some of the nutrients that would otherwise be lost.


----------



## mattolsen (Feb 26, 2009)

I do have a group of 1.2 and I understand that's a possibility. However, I usually always keep 1.1 groups for all my thumbs. Although this group has always done really well in the 1.2 . They both lay and never interact. I'm sure it's probably the case but every time I had found eggs like that there were iso's all over them. I check them several times a day in some cases and I've never observed any ill behavior towards each other. Who knows?


----------



## KeroKero (Jun 13, 2004)

If the eggs got stomped instead of eaten, or there was anything left over in them I could see the isos going to town! I've rarely ever caught frogs in the act of eating or stomping eggs... I can think of only 3 cases over 13 years... and one of those was an anthonyi and they are so bold that almost doesn't count LOL. This is one of those things that is not "aggression" directed at another animal, but something they do to reduce reproductive competition (wanting that male to take care of HER eggs, or limited tadpole sites so reducing competition for HER tadpoles). Not saying that's the case, but I'd believe that before isos eating eggs. I'm not even sure they can get through the gel without it already having degraded. Degraded gel that is hosting fungus and debris? Iso buffet!

Another theory of egg eating - stress. Either being in the tank in general or messing with laying spots.


----------



## Ed (Sep 19, 2004)

KeroKero said:


> If the eggs got stomped instead of eaten, or there was anything left over in them I could see the isos going to town! I've rarely ever caught frogs in the act of eating or stomping eggs... I can think of only 3 cases over 13 years... and one of those was an anthonyi and they are so bold that almost doesn't count LOL. This is one of those things that is not "aggression" directed at another animal, but something they do to reduce reproductive competition (wanting that male to take care of HER eggs, or limited tadpole sites so reducing competition for HER tadpoles). Not saying that's the case, but I'd believe that before isos eating eggs. I'm not even sure they can get through the gel without it already having degraded. Degraded gel that is hosting fungus and debris? Iso buffet!
> 
> Another theory of egg eating - stress. Either being in the tank in general or messing with laying spots.


I have significant doubts that the frogs can damage eggs (particularly newly deposited eggs) by "stomping".... There are a number of descriptions of the resilence of anuran eggs in the literature that include picking them up individually with forceps and squeezing them (see (not free) Xenopus laevis In Vitro Fertilization and Natural Mating Methods) The vitelline membrane of anuran eggs is surprisingly resilent to pressure and while it may allow deformation, it has been shown to withstand up to 5 atmospheres in pressure so the idea that a dendrobatid "can stomp" eggs into being non-viable is at direct odds with the tests in the literature. 

Ed


----------



## Pumilo (Sep 4, 2010)

KeroKero said:


> If the eggs got stomped instead of eaten, or there was anything left over in them I could see the isos going to town! I've rarely ever caught frogs in the act of eating or stomping eggs... I can think of only 3 cases over 13 years... and one of those was an anthonyi and they are so bold that almost doesn't count LOL. This is one of those things that is not "aggression" directed at another animal, but something they do to reduce reproductive competition (wanting that male to take care of HER eggs, or limited tadpole sites so reducing competition for HER tadpoles). Not saying that's the case, but I'd believe that before isos eating eggs. I'm not even sure they can get through the gel without it already having degraded. Degraded gel that is hosting fungus and debris? Iso buffet!
> 
> Another theory of egg eating - stress. Either being in the tank in general or messing with laying spots.





Ed said:


> I have significant doubts that the frogs can damage eggs (particularly newly deposited eggs) by "stomping".... There are a number of descriptions of the resilence of anuran eggs in the literature that include picking them up individually with forceps and squeezing them (see (not free) Xenopus laevis In Vitro Fertilization and Natural Mating Methods) The vitelline membrane of anuran eggs is surprisingly resilent to pressure and while it may allow deformation, it has been shown to withstand up to 5 atmospheres in pressure so the idea that a dendrobatid "can stomp" eggs into being non-viable is at direct odds with the tests in the literature.
> 
> Ed


I had a couple of Varadero eggs/tads that were ready to be transported. I was lucky enough to be in the right place at the right time. I witnessed the male stomping the tad like crazy to finish breaking him loose from the gel. It took a lot of stomping. I was surprised at how rough he was being with them but they were fine. I think they may be in Zookeeper Doug's collection now.


----------



## Shinosuke (Aug 10, 2011)

Ed said:


> I have significant doubts that the frogs can damage eggs (particularly newly deposited eggs) by "stomping".... There are a number of descriptions of the resilence of anuran eggs in the literature that include picking them up individually with forceps and squeezing them (see (not free) Xenopus laevis In Vitro Fertilization and Natural Mating Methods) The vitelline membrane of anuran eggs is surprisingly resilent to pressure and while it may allow deformation, it has been shown to withstand up to 5 atmospheres in pressure so the idea that a dendrobatid "can stomp" eggs into being non-viable is at direct odds with the tests in the literature.
> 
> Ed



Is it just me, or does everyone else dig the way Ed talks? Reading these posts make me feel like I'm watching the discovery channel - it's all educational and sciencey. Who even knows what "5 atmospheres of pressure" is?! If I had that kind of knowledge I would still have just said something juvenile like "PDFs have little wimpy twig legs and their eggs are pretty tough. You can barely smoosh'em with forceps so the whole "egg stomping" thing is a myth"


----------



## Pumilo (Sep 4, 2010)

No doubt about it, Ed is the science nerd. (in a good way, Ed!) I don't know how many times somebody has had to ask, "uhh...yeah, can you dumb that down a little for my poor, little brain?"


----------



## KeroKero (Jun 13, 2004)

Gaaaah this is getting off topic, but very interesting! (maybe these posts should be moved to a new thread?) I have always been amazed at how resilient amphibian eggs have been (baring one incident with Zaparo eggs on an airplane... their eggs and tads may not have read the papers Ed is talking about) but there was always this one situation that was taught to me as "these eggs were stomped", and it seemed likely so I've never really thought much of it. I wish I had pics!!

So the situation is this... eggs usually 48 hours old or under, and when you pull the eggs they are not those tight round little spheres, but rather look like a little slurry from a blender injected into the gel. They are usually gray like infertile eggs would be in color, but I usually saw shades of gray swirled, much like if you were dealing with eggs that hadn't solidly turned one solid color yet (expected given the age of the eggs) and ran through a spin art machine. I usually saw this in female heavy tanks (mostly recently I had this often with a group of 1.3 auratus) and I never saw this develop after I pulled eggs. Some infertile eggs turned to slurry over time, but a much longer time period than 48 hours and the gel often changed consistency too. Egg eating had happened in the tanks and I knew with the auratus that if I saw a female hanging with the eggs it was bad news.

Having seen exactly how fast egg eating can occur (thank you overly female heavy anthonyi group, my finger distracted a male just to have a female come up behind him and go at it!) I figured they just new how to go in and mess up an egg. For all I know having not caught them directly in the act (females messing with eggs, but she was using her mouth so I assumed eating) it could have been failed attempts to eat them because the eggs were old enough that the gel the clutch was in helped protect them (I did notice egg eating happened most with very fresh eggs, yet older eggs after a certain point didn't get eaten??).

If it is something else I'd really like to know about it so I can avoid it in the future.


----------



## Ed (Sep 19, 2004)

Pumilo said:


> I had a couple of Varadero eggs/tads that were ready to be transported. I was lucky enough to be in the right place at the right time. I witnessed the male stomping the tad like crazy to finish breaking him loose from the gel. It took a lot of stomping. I was surprised at how rough he was being with them but they were fine. I think they may be in Zookeeper Doug's collection now.


I have some significant skeptism that we are correctly interpreting this behavior as well... It takes less than ten minutes a day for a male in the wild to wet the eggs (which could in part account for a lack of observations of it), but the behavior often described as "stomping" is the same behaviors that males engage in when wetting the eggs. Given that this behavior begins with deposition, I'm suspicious that "stomping" to get the tadpoles out of the egg is a correct interpretation. The assistence to the tadpoles may simply be incidental to wetting the eggs... If the tadpoles actually required assistence to escape the egg, we should see more issues with artificial rearing... 

Ed


----------



## Ed (Sep 19, 2004)

KeroKero said:


> G
> So the situation is this... eggs usually 48 hours old or under, and when you pull the eggs they are not those tight round little spheres, but rather look like a little slurry from a blender injected into the gel. They are usually gray like infertile eggs would be in color, but I usually saw shades of gray swirled, much like if you were dealing with eggs that hadn't solidly turned one solid color yet (expected given the age of the eggs) and ran through a spin art machine. I usually saw this in female heavy tanks (mostly recently I had this often with a group of 1.3 auratus) the future.


Infertile eggs behave and look this way. They don't undergo the rotation in which the "vegetal pole" ends up on the bottom which leaves you with the yolk distribution which can look like they are swirled. 

Fertile eggs are described in the literature of having a much greater resistence than infertile or deceased eggs (In one of the references listed above, squeezing them with forceps potentially could be a diagnostic for fertile eggs) very early in the developmental process. 

There are a number of potenial reasons for the appearence of the eggs.. for example, eggs can look that way before rotation of the nucleus of the egg occurs leaving the "vegetable pole" uppermost (which is the swirled appearence") and a delay in that rotation may indicate issues with development. Given that we also now know that nutritional levels of the frogs in the past several decades was often suboptimum due to hypovitaminosis of A, which is a direct indicator of successful fertility we really should look at these incidents with a critical eye. Did you consider that the females may also have been preventing proper care of the clutches through sexual interference? 


Ed


----------



## Pumilo (Sep 4, 2010)

Ed said:


> I have some significant skeptism that we are correctly interpreting this behavior as well... It takes less than ten minutes a day for a male in the wild to wet the eggs (which could in part account for a lack of observations of it), but the behavior often described as "stomping" is the same behaviors that males engage in when wetting the eggs. Given that this behavior begins with deposition, I'm suspicious that "stomping" to get the tadpoles out of the egg is a correct interpretation. The assistence to the tadpoles may simply be incidental to wetting the eggs... If the tadpoles actually required assistence to escape the egg, we should see more issues with artificial rearing...
> 
> Ed


OK, I'll buy that. I didn't stick around long enough to see the whole thing as I didn't want to interrupt him. The next morning one had been transported and I simply assumed.


----------



## Ed (Sep 19, 2004)

Pumilo said:


> OK, I'll buy that. I didn't stick around long enough to see the whole thing as I didn't want to interrupt him. The next morning one had been transported and I simply assumed.


 
It's not an absolute.. just me being skeptical that the hobby has the correct reason for the observation.... 

Ed


----------



## mattolsen (Feb 26, 2009)

I would definitely believe that, by the time the eggs are permeable enough for a tad to break through, it wouldn't be that hard to help the tad out of the egg.

Also, I understand the concept of anti-cuckoldry behavior in supposed monogamous species. Although, if we are suggesting that anti-cuckoldry behavior is the likely scapegoat do you believe this behavior can develop over time? Because there were previously multiple clutches in the tank at the same time when that same group was in a smaller tank with less deposition sites than they are in now. 

This is all just interesting to a bio geek. I'm interested in the concept of imitators supposedly being monogamous in the wild, but my first few having the greatest reproductive success in a polygynous ratio.


----------



## KeroKero (Jun 13, 2004)

Ed said:


> Infertile eggs behave and look this way. They don't undergo the rotation in which the "vegetal pole" ends up on the bottom which leaves you with the yolk distribution which can look like they are swirled.
> 
> Fertile eggs are described in the literature of having a much greater resistence than infertile or deceased eggs (In one of the references listed above, squeezing them with forceps potentially could be a diagnostic for fertile eggs) very early in the developmental process.
> 
> ...


I knew the color and pattern what characteristic of infertile eggs, the shape what not which I think is where the "they must have been stomped!" came from. It wouldn't surprise me about the structure of the egg being weak enough and degrading that maybe just the weight of the animals on them could have given them that squished look. I've studied the tadpole Gosner stages a number of times but just didn't know how you got nice round globe to squished mush without something being different.

Sexual interference is a given and witnessed, which is why at least with the original groups that were female heavy were dealt with by separating them out. I couldn't do that with the last group of animals as I just worked with them - they did have nutritional issues as well as they were part of the group I talked to you about. I was hoping to house each girl individually and rotate the male through but that plan was never put into effect. 


I agree with Ed on the "stomping to get the tads out" bit... I've been lucky to work with a few very bold animals and see the behavior (which is amusing and can involved butt wiggles on the eggs and significant small movements that may look to be "stomping"). Given how easily some eggs hatch when just lightly sprayed with water I know it doesn't take much when they are ready... I often wonder if being wet by a parent may be part of what triggers a mass hatch in group tadpoles as they tended to be mostly at once, while individual raised tads seemed to stagger hatching more.


With the greater luck in a larger group with some PDFs, I've always wondered at the role of competition in their breeding... Sometimes it seems like just hearing or occasionally coming across a member of the same sex can invigorate a pair, but that doesn't mean that extra animal is involved - but I'm convinced egg piracy occurs in PDFs pretty well so confused genes in a clutch could be from the "third" (or fourth, or fifth...) wheel sneaking in and getting at eggs. Extra males may lead to egg piracy, extra females just may lead to less egg fertility due to the male being so distracted with courting and keeping his eggs good, or egg eating more directly. I think many PDF breeding roles are similar to some songbirds... pretty monogamous looking for a season, but genetically you've got males sneaking off, and females breeding with multiple males in increase chases of fertility. They look like a pretty stand up pair feeding babies though!


----------

