Roger Gilbert's picture

Star Jelly ? Frogs innards ?

Observed: 31st January 2013 By: Roger GilbertRoger Gilbert’s reputation in Amphibians and ReptilesRoger Gilbert’s reputation in Amphibians and ReptilesRoger Gilbert’s reputation in Amphibians and Reptiles
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Description:

The Jelly was spotted first and 60 yards away I found the Frog near one of our ponds either it was discarded or I disturbed a predator.
Could the Jelly be a fungi ?

Identifications
Species interactions

No interactions present.

Comments

Thistle's picture

Frog spawn

There has been much speculation about the source of this jelly here and elsewhere. This is the first time I've seen it positively connected with a frog: many thanks. I suspect these photos will be cited frequently in the future.

Roger Gilbert's picture

Thanks Ian,

Without iSpot I would not have been aware of "Star jelly" and been able to put the associations together. It is stunning how similar the "jelly" coming out of the frog is to the "Star Jelly". The unfertilised spawn would have no black tadpole centre and be an overall white jelly. There are Heron on the site so I think that would have been the predator.

Howardian Local Nature Reserve
http://www.howardianlnr.org.uk

nightfly's picture

Roger these are good images.

Roger these are good images. Jelly production from the source(the most common source).

Cathal.

dejayM's picture

caution

"...unfertilised spawn would have no black tadpole centre and be an overall white jelly..."
See the sequences here (of course you have..!!)
http://www.ispot.org.uk/node/317681
You trained me and I accept, that eggs are fertilized outside the frog. So what is the mechanism (and purpose) that produces 'star jelly' inside a frog?
Yes, excellent photos Roger
Derek

nightfly's picture

Hi Derek,Could you give the

Hi Derek,

Could you give the source of the above quote? The ova exist before fertilization, ie the black centre. They get their coating of jelly inside the female but its a thin dense coating which requires immersion in water in order to swell into what is recognisable spawn. Fertilization can only really occur immediately after its released by the female- externally and prior to swelling up into full sized spawn.

I am not fully certain of this but it appears to be the case that the ova receive their jelly coating in the long convoluted oviduct inside the female. This is suggested also in a comment by Masked Marvel on that other observation that you have linked-"According the Malcolm Smith's New Naturalist book they receive the coating as they pass down the oviducts."

This would seem to make perfect sense, ie the oviduct adds the gelatinous coat to the ova after it is produced by an ovary, after which they are stored in the ovisac until such times as spawning takes place.

I'm not a frog biologist and I stand to be corrected on any of these points but it looks like the oviduct, if I am using the correct terminology, is the jelly producer. It must be borne in mind that the jelly only becomes jelly on contact with water. It cant become its full mass until it comes into contact with water either by immersion or in very wet conditions on land.

The dead female in my other observation didnt produce star jelly when left in water overnight but it did produce a full load of proper spawn. On other occasions masses of ova-less jelly are produced as many observations illustrate. All I can suggest as a possible explanation for this is that the gelatinous matter which becomes the jelly in those frogs hadnt yet been applied to the the ova in those cases. Maybe its just that the spawn production process was not as advanced in those individuals. This isnt meant to be a definitive expalnation, merely a possible one.

It would be great if someone who really knows about frog biology could clarify the process of spawn production for everyone interested in this subject.

Cathal.

dejayM's picture

missed

I guess you missed the original statement when you agreed with him, but it's here, above, in Roger's first comment ("Thanks Ian").
I simply thought you were off track when you wrote "jelly production from the source...."
We both know that the eggs are fertilized at the point of lay but we should also accept that the eggs are otherwise complete inside the mother to be - albeit that the coating goes througha process. That leaves the issue of what is the jelly in which there are no discernable eggs (Star Jelly). A phantom pregnacy perhaps, an immature female, a mature female without viable eggs (just jelly?)...it goes on.
Your disected frog closes quite a few options and is pretty conclusive material.
But where, anatomically, does the 'star jelly' in THIS post originate?
Derek

nightfly's picture

Hi Derek, My best guess at

Hi Derek,

My best guess at present is that the jelly is produced by the long convoluted oviduct(or the long convulted pipe like structure through which the eggs pass which I am calling an oviduct). Its visible in quite a few observations and in the dissected frog in my observation with ova within it. I think that pipe produces the jelly and indeed applies it to the ova as they go through it, as stated above.

Cathal.

nightfly's picture

Ova-less jelly might be

Ova-less jelly might be explained by the jelly producing organ being exposed to water by the action of a predator before the frog has actually got round to applying the jelly to its ova- a reservoir of jelly which was going to be put on ova IF the animal hadnt been killed and opened. Just a possible explanation, not a confirmed fact of course.

Cathal.