<i>Hynobius tokyoensis</i>

TJ

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Tim Johnson
Picked these up at a shop today -- for free
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The shop was too hot and the eggs were going bad so I volunteered to take them off their hands. Three larvae have left the eggs sac so far.

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Henk or anybody else who might know: is it typical for the egg sacs to turn milky like this or do these look to be in normal condition?

I do detect what seems to be some sort of fungal growth on the sacs but it seems many larvae will make it out in time given their advanced state of development.
 
The eggsacs I had of Hynobius tokyoensis were all transparent Tim. When the eggsacs turn white this usually means something is wrong...(might be just the temperature, but I am not convinced). Also I find hynhobius eggsacs to be quite fragile when it comes to changing the waterconditions, they just don't seem to cope well with that.. had some troubles with this before. Currently I leave the eggs in their natural water. Temperatures overhere are 10°C in the water . for now I have eggsacs of H. retardatus (2) and one half H. nebulosus eggsac. The Hynobius lichenatus male is also quite active and up to 12 male H. dunni wait for the females to arrive. My H. leechii are still quite calm. I only hope that the H.nebulosus eggs are fertilised.

I hope you can find some tubifex for these larvae, you'll see they adore this. Daphnia's are also taken...

Hope you succeed raising them Tim. Feel free in aksinbgg further adivce, burt please take note that I will be absent soem time next week due to my trip to Prague.
 
Hi Henk,
I now clearly see the difference between healthy tokyoensis egg sacs and unhealthy ones! Today I came across these:

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The larvae in the pics I posted before are evidently premature hatchlings.
I've started them out on brine and will later switch to tubifex. Good luck with yours!
 
Here are the adults:

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(photos taken in the shop)
 
Amazing to see them like this...on the verge of hatching but still in a state of suspension (this is the sac I brought home).

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Thought I'd get more larvae from the 2 unhealthy sacs in the first several pics above, but ended up with only 4 -- all premies. The sacs became covered in fungus even though the water was kept cool and aerated. Contrary to what I'd initially thought, the larvae were definitely NOT in an advanced state of development!
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Question: what's with the white undeveloped eggs in these sacs with the larvae -- is it safe to assume they're all duds?

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Got things mixed up there, but those larvae pictured above are hatchlings from the new, healthy egg sac.
 
Two days later and most of the 40+ larvae have left the single sac. They're feasting on brine but already seem big enough to handle the smallest tubifex worms. Nine undeveloped eggs remain in the sac. Is it typical for each sac to contain some of these?

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TKS! Re: the first 2 of the 4 new pics, it's rare for my camera to capture a subject in such clear focus from that short of a distance. Sometimes it just...happens!

None of the 4 premmies from the unhealthy sac survived. The ones from the healthy sac are doing fine -- with the possible exception of any that may have been cannibalized, which seems to be often the case with Hynobid larvae. They're growing rapidly so I've had to move them to a larger tank.

I decided to remove the egg sac, which still contains the same number of dud eggs.

After only a week or so since hatching, they're already feasting on tubifex. Brine shrimp are starting to seem too small for them.

Compared with Cynops larvae, their feeding manner is quite aggressive. They frequently target the same worm, and I've intervened several times, worried that the struggle might end up with the bigger larvae cannibalizing the smaller one as an extension of the worm!

When the tubifex ball up, these larvae can exert considerable force to pull individual worms out. Violent little buggers!

I'm now on the lookout for other Hynobid larvae to compare them with. 'Tis the season, after all!
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I was surprised to learn today that female hynobiids deposit egg sacs containing UNFERTILIZED eggs, which are then fertilized externally rather than internally as in the case of many other sals.

http://www5d.biglobe.ne.jp/~hasumi/doc1/hyno_e.html

Dr. Hasumi also explains on his site how the males "midwife" the delivery of the egg sacs and then compete to fertilize the egg sacs.

http://www5d.biglobe.ne.jp/~hasumi/figure/spawn_e.html

Fascinating stuff!

But I still can't quite figure out how the sperm manages to penetrate the (permeable?) egg sac to fertilize the eggs (esp. considering how spawning occurs in the water), and whether it reaches only some eggs and not others (which would account for my duds!). Also, is a single male necessarily responsible all fertilized eggs in a single sac or can there be multiple males?
 
Serious feeding = serious growth. That seems to be the equation here. God forbid they morph on me anytime soon! Might have to cut their rations to extend their childhood
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Does increased feeding mean faster morphing or just morphing at a larger size?

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Doesn't anybody else out there keep Hynobiids? I have a zillion questions but guess I'll have to wait for Henk's return from the Czech Republic...
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Word has it that some Japanese newtkeepers monitor this site...but they're probably hesitant to join in, language concerns and all.
 
Noticed some cannibalism. They're now feasting on frozen bloodworm, occasionally wrestling for the same worm.

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Hi Kamil. I refer to that site quite frequently but I've never had any contact with him yet and didn't know he breeds them. TKS!

Have you any tokyoensis that've morphed? Any success in rasing them? I'm interested in hearing more about methods of rearing morphed hynobiids, though I plan to release most of my tokyoensis larvae back into the wild before they morph (after confirming whether this is environmentally sound or not).

There's a group of dedicated people here in the Tokyo area working to preserve H.tokyoensis, whose members have conducted surveys, mapping out areas where its extinct and where its endangered.
 
In answer to my own question, I happened across this tokyoensis pic that shows how the male externally fertilizes the eggs:

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Source: A Photographic Guide: Amphibians and Reptiles of Japan

(picture by Kenji Numata)
 
Hi Tim!

Yes, I have 2 juveniles. As far I have been told, they like it wet and cold, so i keep them. The one is growing quite fast in this surrounding, the others keeps rather small...
Kei told me that they are to keep like Firesalamander (Salamandra s. )...

I don't have any written word about H. tokyoensis at home...
 
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