Nominate C. ensicauda -- terrestrial egg deposition

[TJ]

 

[TJ]

 

[TJ]

 

[TJ]

My C. ensicauda popei are also laying eggs on moss:

 

[terry]

Very interesting picture of C.e.popei eggs on the moss Tim. Are they laying on the moss due to "overpopulation"? or avoiding predation?. How many individuals are in the tank of which she was laying?

( Which makes me wonder why the female is paying frequent visits to the mossy log in my tank).

 

[TJ]

Thanks Terry.

Well, those are the two hypotheses I've heard on why C. ensicauda sometimes opt to lay their eggs on land rather than on plants in the water, but I doubt it's been scientifically studied in detail yet. There are over a dozen popei in that 90x45x45 tank (all of which I caught in northern Okinawa a couple of years ago). It has larvae in it pretty much year-round. The tank with the nominates pictured at top only as around 8 newts in it and is exactly the same size, so certainly not overpopulated.

In the above tank, I suspect eggs are also being laid on plants in the water, but it's an established tank in which it us difficult to see much because tanic acid from bogwood has stained the water. In the nominates' tank, I've seen eggs laid on Egeria densa but they're eaten pretty quickly. I've observed predation of eggs both on land and in the water, but there's probably less predation of eggs on land in the wild than in captivity.

Anybody, what are some other salamander species that lay eggs both on land and in the water?

Here:

http://www.caudata.org/cc/images/species/Cynops/C_ensicauda11Johnson.jpg

...is an old picture of the same tank and same occupants, before I moved house and had to rearrange it. It's a bit more "wild" now

(Message edited by TJ on January 23, 2006)

 

[terry]

Hello again Tim

I wonder if this behaviour has ever been documented in the wild. Have you observed anything like this during your excursions? I was beginning to speculate that this behaviour may be an adaptive response to an enclosed environment, the same may or may not happen in the wild. Then again I am merely speculating. It could be; like you said, a way of avoiding predation. Ed Kowalski and Henk Wallays also recorded newts laying eggs on moss or on land. So far we have observations of Cynops p.sasayamae, C. cyanurus and C. e. popei depositing eggs on land. Were all of them in enclosures as well?

In my case the female has been exhibiting such behaviour similar to your newts, choosing the sections of pillow moss just above the bank. I'll take some shots if anything else occurs.

(Message edited by terryschild on October 20, 2005)

 

[TJ]

Hi Terry. Yes, it's been documented that C. ensicauda lays eggs on land in the wild too -- apparently in some localities more than others, leading to the speculation as to why. Pond population has been put forward as a possible factor. But there is so little attention given by the Japanese scientific community to the habits of this species, so who really knows why these newts do what they do. It could be genetic predisposition, as species are constantly evolving and adopting new patterns of behavior to adapt to their changing environment and all. There are introduced species such as American crayfish and various foreign species of fish that never were around before, and which prey on newt eggs and larvae. It could merely be or partially be a question of availability of suitable oviposition sites. Heck, it could be simply individual preference because even siblings exhibit different behavior patterns. Maybe these newts laid eggs solely on vegetation in the water thousands or millions of years ago, and are now in a transitory period, becoming like sympatric E. andersoni, which lay eggs only on land. I don't recall my other Cynops laying eggs on land, but then again I haven't provided them with suitable land oviposition sites...

 

[TJ]

Terry, sorry but I accidently deleted your last post.

Anyway, you were asking about trying out similar land areas for other Cynops species, to see if they would lay their eggs on land. Well, I already have a nice moss & bogwood land area in my Cynops cyanarus tank, but I've only seen them leave the water once or twice -- and they haven't been laying eggs, even in the water, for about a year. I'll keep an eye out though

 

[terry]

You...deleted my last post

!

(Chuckles) Please keep me updated if anything of the sort happens to the other Cynops species (egg laying of course, not deleting of newts)! Thanks!

In the meantime, the female still inspects areas on the mossy bank as I write.

 

[TJ]

What I did was I accidently edited your previous post instead of replying to it, so it ended up with my message under your name. I found I couldn't undo what I had done, so I just deleted it...

I'm trying without luck to recall whether my C. pyrrhogaster have ever laid eggs on land before, but my memory either fails me, I never noticed it or it never happened. Anybody else observed terrestrial egg deposition with this species?

It seems Tylototriton shanjing is one example of another species that lays eggs both on land and in the water. See:
1) Ye, C.Y., Fei, L., Hu, S.Q. (1993): Rare and Economic Amphibians of China.
2) Sparreboom M., Xie, F., Fei L (2001): Reproductive behaviour of the Chinhai Salamander (Echinotriton chinhaiensis) (Caudata: Salamandridae)

Laying eggs on land may eliminate or at least minimize some predation by newts, fish, dragonfly larvae, etc., but there are surely land predators to contend with. It also doesn't minimize the hazards of the free-living larval stage for individuals, though there is surely greater overall survivability in larger numbers

(Message edited by TJ on October 22, 2005)

 

[terry]

Thanks Tim!

I read the pdf file of the Chinhai Salamander. The question is: The eggs that were laid on land. How do the young larvae survive? Do they flop down into the water again since they do not hatch as fully developed metamorphosised individuals. I would speculate they would be laid closest to a water spot the way some anurans position their eggs over water. Then again I cannot imagine a tiny hapless larvae squirming back into the water. It would be interesting if the larvae were like the Dendrobates who could survive for a while on the backs of the adults before deposited into a suitable water habitat.

Another approach (MO) is a jettysoning of eggs on land since there was no suitable spot for the female newt/salamander to lay in the water. Though I highly doubt that.

 

[TJ]

Well that Chinhai report mentions in passing about Tylototriton shanjing laying eggs both in the water and on land, but just for clarification here, it does not say that Echinotriton chinhaiensis lays eggs in the water -- only on land.

As for the Echinotriton larvae, yes, that's exactly what they do -- flop and squirm down into the water. They can easily move some distance that way. The eggs are laid only quite close to water, mostly on the edge of the water, at least in my understanding. That's kind of obvious. But it does seem that rain stimulates their eggs to hatch, and so I guess larvae some distance from the water's edge can sometimes rely on being washed down into the water by the rain without much individual effort. Eggs are often laid on slopes, perhaps for this reason. I've been in E. andersoni country, and believe me, when it rains, it pours!

The Echinotriton larvae are not as hapless as you might think, as I have seen through raising some E. andersoni from eggs.The same goes for C. ensicauda larvae that hatch from eggs laid on land, they most likely find their way to the water without too much problem. But it would be neat to see a study on survivability of eggs and hatched larvae comparing eggs laid on land vs. those laid on plants in the water for this species

I wish somebody with experience with other salamander species could weigh in here with some scientific knowledge about similarities that we could draw lessons from. I sure ain't no scientist and hope I don't sound like I'm pretending to be one

(Message edited by TJ on January 23, 2006)

 

[terry]

Well Tim, That seems to be a logical and reasonable explanation! I did not think about the rainfall as being a factor to help the young larvae on their way but then again I was probably thinking about what would happen in an enclosed environment i.e. a tank such as your or mine or anyone who keeps the species.

Scientific explanations sounds fine and dandy but it is usually the observations of the layman such as you and I ( and the rest of our loving newt and salamander enthousiasts!) which contribute a lot to the scientific journals without being actual scientists ourselves!

As for your colonies of terrestrial egg laying caudates, I say GANBATTE!

(Message edited by terryschild on October 22, 2005)

 

[edward]

As a side note some Asiatic caecilians lay thier eggs in burrows along the sides of the streams (out of the water) and the larva on hatching move into the water.

Ed

 

[terry]

And there are also records of caecilians coiling round the eggs. or was that sirens?
Terry

 

[TJ]

Caecilians do indeed coil around their eggs, or at least some of them do as I know since I recently copy-edited a scientific paper on this very subject and have seen pictures of it too.

Anyway, here are some more Cynops ensicauda popei eggs:

(Message edited by TJ on January 23, 2006)

 

[felipe]

Tim, sorry, but... could you please post a picture of the entire tank??? looks amazing! Thanks!

 

[erik]

wow thats so cool, i wonder what happens when they hatch? will they just cral into the water?