It's always worth it to go out (for Salamandra) ;-)

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Re: It's always worth it to go out (for Salamandra) ;-)

Postby Patrick Masius » Wed Dec 12, 2018 4:56 pm

Ilian Velikov wrote:
Jeroen Speybroeck wrote:The fact that the smaller one seems to be climbing up, is a bit of a brainteaser too. Salamanders are found quite often climbing the lower tree, even up to half a metre above the forest floor. Tree trunks may channel rainfall to the forest floor, so a salamander seeking moisture may like to mount the tree base. Or is it the ample food items (like harvestmen, woodlice, spiders, slugs, ...) that can often be found on the lower part of the tree trunk which lure them up the tree? Females do it too, so sniffing up pheromones may not be the answer. What do you think?


Even though trees channel rain water I think the leaflitter would still be much more moist than a tree trunk. After all the trees channel the water to the ground. The more logical thing if seeking moisture for me would be to bury in the leaflitter. Could it be warmth? You mentioned temperatures are low and even a few centimeters above ground would be slightly warmer. Also in winter wood/tree bark always seems to be warmer to the touch than other natural materials such as stone, mud, leaves, etc.


Interesting discussion!

My friend, Andreas Pix, and I found 16 Salamandra s. terrestris outside on a warm wet day in spring (26 April 2013) in central Germany (Hann. Münden). Many of them tried to climb up tree trunks. Temperatures were above 15°C, so I would not buy the temperature hypothesis.
As a historian, I tend to believe in some atavistic behavioral pattern rather than in funtional explanations. :ugeek:

I add pictures of evidence, though there is more material, including videos, if somebody is interested.

Firesalamander.jpg

Firesalamander-II.jpg
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Re: It's always worth it to go out (for Salamandra) ;-)

Postby Ilian Velikov » Wed Dec 12, 2018 5:44 pm

Jeroen Speybroeck wrote:If you look at it like this, the difference between ovoviviparity and viviparity becomes much more (at least evolutionary) fluid than we might want to think when we want to say that taxon A does and taxon B doesn't have it.


I agree, the line is quite blurred.

Jeroen Speybroeck wrote:In part due to what I wrote about intrauterine stuff, clutches largely consists of many small larvae or fewer larger ones. Yes, the larger ones can eat the smaller ones. As deposition period is quite long, smaller larvae can also become prey just because they were deposited later on. Cannibalism is particularly common in small waterbodies (of course...). Partial cannibalism can leave signs into adulthood - tail tips, feet, toes, ... are often bitten off and may regenerate only partially. The spot I mentioned that has yearround ground water here in Belgium has a clearly much higher percentage of (post-metamorphically observed) mutilated animals, often leading to weird, stubby toes, but sometimes leading to regeneration errors, such as 6 toes or even a smaller fifth leg.


Come to think of it, I guess you are right. I was at the breeding spot today and intentionally looked at the size of larvae which were deposited more or less at the same time (within the last 2-3 days) and they are pretty much the same size. It certainly makes sense that cannibalism would be more common in smaller water bodies but although this one here is tiny I've never seen mutilated larvae or adult ones. I guess there might be more (invertebrate) food than I think there is.

Patrick Masius wrote:Many of them tried to climb up tree trunks. Temperatures were above 15°C, so I would not buy the temperature hypothesis.

Patrick, thanks for the photos. Of course it is difficult to say but I would not think that the individuals from your photos are purposefully climbing for one reason or another. It seems to me that they just stumbled upon an obstacle and are simply trying to avoid it. I personally have not observed any climbing salamanders, so maybe Jeroen might have a more valuable input (and maybe photos?)
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Re: It's always worth it to go out (for Salamandra) ;-)

Postby Jeroen Speybroeck » Wed Dec 12, 2018 6:06 pm

Take a close look at the toes of the larvae and their tailtips. Could be you will see some toes don't look as they should. But of course if the big guys eat all the small ones as a whole, there won't be much nibbling. And it is density-dependent - if there are not that many larvae (and mothers) and plenty of Gammarus, it becomes rarer, I guess, even in small waterbodies.

I have loads of tree climbing evidence but none whatsoever of diurnal activity at my spot. Note that especially males are frequently found right next to trees (proximity to shelter, orientation, territorialism, ...) - the climbing has to be something else imho.
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Re: It's always worth it to go out (for Salamandra) ;-)

Postby Jeroen Speybroeck » Mon Dec 17, 2018 6:53 pm

Jeroen Speybroeck wrote:
Michal Szkudlarek wrote:
Ilian Velikov wrote:Michal, that's very interesting! Do you have a source? I thought salamandra larvae are enclosed in egg capsules while inside the female.

They can leave egg capsules. Piotr Sura wrote in his book published in 2005 that adelophagy is known in Salamandra atra, Salamandra lanzai, 2 subspecies of S. salamandra, Lyciasalamandra spp. and Typhlonectes compressicaudus. Włodzimierz Juszczyk wrote in the eighties that this phenomenon can be present in axolotls and in oviducts of S.salamandra and it happens when female is far from water and does not give birth to larvas.


Hmmm... I'm not sure if S.s.t. and S.s.s. do this very often, or at all. While infertile eggs most often are part of the clutch, most S.s.t. larvae I have seen being born only pierce through the membrane that surrounds them after leaving the female's body. My experience is limited, but come to think of it, I do remember that this was not the case with fastuosa's that I saw hatching - big larvae within membrane as soon as they leave the female's body. Bernardezi is know to display adelphophagy (Dopazo & Alberch call it siblicide), presumably promoting intrauterine larval competition and finally viviparity. It seems quite obvious that adelphophagy would occur if/when larvae remain longer in the uterus (which can be due to several reasons e.g. due to seasonal lack of water). Once they have spent all their yolk, they can leave the membrane and feed on infertile eggs or smaller siblings inside the uterus. If you look at it like this, the difference between ovoviviparity and viviparity becomes much more (at least evolutionary) fluid than we might want to think when we want to say that taxon A does and taxon B doesn't have it.


Read just now that other brother-eater besides bernardezi would be fastuosa.
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Re: It's always worth it to go out (for Salamandra) ;-)

Postby Ilian Velikov » Fri Mar 01, 2019 9:46 pm

Not as interesting as adelophagy but a curious experiment I tried with my daughter with the local Salamandra larvae, and which is quite fun especially in winter/early spring months with little to none herp activity - we put Gammarus on the tip of a thin stick and offered them to the larvae placing it at a few millimeters of the head of the larvae. The tiny salamanders would readily attack and eat them. They would bite and vigorously shake and throw themselves about to dislodge the food from the stick. We tried this on several occasions on different days and all except one (small) larvae took the food. It works best if the food is offered to the side of the head or body rather than in front. It looks like they use a combination of scent and movement ( lateralis system..? ) to detect prey. It was as close as I've ever been to hand-feeding a wild animal, and a rather unusual one at that. Of course, we try not to make a habit out of this...
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