kingcutgroover1 says:

We found this giant tadpole in the pond. Shown with regular tadpoles and 50p piece for scale. Any ideas?
www.flickr.com/photos/24699079@N06/4642473276/in/pool-bbc…
Posted at 5:50PM, 26 May 2010 BST ( permalink )

Cosper Wosper says:

I had some ‘giant’ tadpoles in my pond a few years back, they turned into ordinary frogs. It seems that some years some tadpoles don’t finish ‘cooking’ and these ‘par-boiled’ ones ( wheather permitting ) sit around on the bottom of the pond, they seem to get a good head start the next year, I think its just natures way of spreading the load.
:@)
Posted 2 weeks ago. ( permalink )

the longhairedgit says:

Giant tadpoles are usually the ones that take to cannabilism and scavenging the best, many hundreds of frog species give their ‘poles two options in life, feed on their brethren leave the pool early, getting mobile before the pools dry up in hot years, or those that feed more on myofauna and algaes and have a slower growth rate in cooler years, leaving the water with better structural physiology due to the better balanced diet and more thorough slow growth.

Some may fail to metamorphose in time for the years end or literally cannot metamophose because of abnormally low levels of iodine in food sources and water, and others may be inhibited developmentally by heavy metals and even trace hormones from birth control pills in the watercourses. It tends to happen more often in ponds than in nature because tapwater and rainwater is often mineral deficient. If however you fert your plants in your pond with compounds including iron and iodine and various salts in the mix, rarely will you get a tadpole that fails to metamorphose. Wherever your stats are good on trace nutrients, and of course the other big factors that affect respiration, stable temperature, reasonable o2 reading, no hydrogen sulphide, nitrate under 40ppm, nitrite and ammonia stats zero, mature and balanced bacterial cultures of both aerobic and anaerobic bacterial colonies helping keep things clean, you’ ll get fairly normal development.

Different years favour different paths of development. Its a little threeway system that many frogs, toads, newts and slamanders can employ. In any given group of ‘poles, there are specimens that have these individual tendancies, sometimes triggered by environmental changes, sometimes its a path of life thats dictated by the parents genetics, sometimes they take on a different style of life regardless of external conditions.

As far as odds go, the overwintering tadpole is a much rarer phenomenon than the cannibalistic protein feeder for being the larger tadpole.
Originally posted 2 weeks ago. ( permalink )
the longhairedgit edited this topic 2 weeks ago.

Mike_Foster says:

Yep – every time I’ve raised tadpoles this has happened. Some are more voraciously carnivorous/cannibalistic than others so that in times of slack food resources/cramped/evaporating pools some survive rather than all starving to death. With a large and plentifully fed environment the more browsing strategy is more successful in greater numbers and you’ll get a lot of tiny tadpoles growing more steadily and able to avoid being munched more effectively.

If they’re in a tank then the cannibals have a captive banquet.
Posted 2 weeks ago. ( permalink )

Cosper Wosper says:

That may be so, but I drain and clean my before the frogs spawn so as not to loose any. Its then that they come up in the net, sometimes with and sometimes without legs. Most tadpoles are omnivours and are happy munching on dead worms and slugs that have fallen in, I’ve netted a dead goldfish out before and found tadies sucking away at the flesh… which is nice. :@)
Originally posted 2 weeks ago. ( permalink )
Cosper Wosper edited this topic 2 weeks ago.

the longhairedgit says:

Oh yeah, they are nearly all opportunist, but some will take only animal protien as food, and never look at plant or myofauna twice. There are definitely different, confirmed, and very well researched developmental paths that tadpoles can take. Its just the point at which they chose to take it can vary wildly. If something dies thats total natural behaviour to take advantage, but the cannibals actively hunt, latching onto others weakened or not and start chewing away. Most tadpoles don’t do that.

In aquaria it will be more common because of the rise of chemical signifier levels put out in the water by the tadpoles themselves, serves as indication of a high population density, just like territorial triggers in various fish can be massively heightened in the confines of an aquarium.

Some cichlids for example do it so profoundly that they can cause the phenomena in aquaria known as “cichlid mist” even when massively overfiltered and purified and chemically tip-top,, and they too will start some seriously and often violent competitive behaviour way beyond the wild average.

With amphibians, a lot will be triggered into cannibalism by the chemical knowledge of signifiers given out that pre-empt the water quality becoming foul., because theres no filter media that can take them out. Even carbon, zeolite, nitrate absorbers and uv sterilisers can’t catch them. The ‘poles know that with a high population density its better to eat someone, grow in double-quick, even triple-quick time , and get out before the pool goes toxic. Its a primal evolutionary trigger and they can’t stop reacting to it defined by millions of years of pattern in the environment.

You put four tadpoles in a 40 gallon tank with tropical fishkeeping standard maintenance, the sort of excellence standard in water quality and excellent understocking principles expected for say discus cichlids, and they won’t touch each other 99% of the time, you put 40 tadpoles in the same volume, 10% or more might become cannibals. Only incessant partial water changes are likely to slow it down. Even if you take the cannibals out as you go, you keep getting more because the chemical signifier level hasn’t dropped, and is ever increasing.

If you have goldfish or carp like in your average UK garden pond, (an estimated 80% of fishkeepers keep their ponds in a state of unhealthy overstock) the pond is almost almost always in a state of biochemical and waste overstock before even the tadpoles arrived, and bingo, what you will have is a lot of tadpoles scavenging like crazy and cannibalising each other to get the hell out of there because not only will the water quality not be great, but in the coming weeks could be significantly worse.

Thats basically why people see so much of it – overstocked ponds. Not that frogs and toads arent capable of overstocking almost any water body they lay eggs in, if they do so in number, but in the garden pond they are less subject to predation, and consequently don’t get their numbers thinned out as quickly as they normally would, being as they are protected by the resident human, and segregated from the majority of species that would eat them, you can’t for example expect there to be much in the way of diving beetle larvae or dragonfly larvae in a pond because the fish eat them, the more aggressive freshwater fish typically arent kept in ponds, and most goldfish and koi find tadpoles distasteful, and we keep herons and egrets away, and the shyer waterbirds won’t come near a house.

Generally the smaller the body of water, and the sooner its overstock limit reached, the more likely there are to be problems.
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A side note about our froggy friends.

Together with aeromonas bacterial strains introduced from asian bred goldfish and koi, and chytrid fungus from african and asian locations coming in from the pet trade, amphibians have had a hell of a time over the past 20 years. you see, since records began amphibians are in a 90% across the board population decline, and that sounds bad, but its actually worse than that because records do not go as far back as the deforestation and major wetland draining times in england caused by farming. In reality over the last thousand years amphibians have suffered a 99% drop in viable breeding habitat, and 99.95 percent drop in overall numbers compared to the once truly wild britain.

Add to that that predatory waterfowl congrgate in concentration on the last wetlands, and that the water quality of bogs, swamps, reedbeds , etc are pushed to maximums, and what you have is frogs helping to reduce their own numbers by forced cannibalism too. Also the evolutionary path of frogs will have changed to inordinately favour the cannibalistic ‘poles just as they do in more extreme environments where there are only seasonal rains.Add pollutiopn to that equation and it becomes clear that our native amphibians are in real deadly trouble, literally under an extiction threat within a few decades.

No wonder people arent seeing so many grass snakes. Their primary prey item has had a 99.95% reduction in population over a thousand years. Personally I think we need to create four times the amount of existing wetland and reed bed habitat almost immediately in the uk just to stop them going into a state of genetic population collapse where fertility and breeding at all becomes an issue.

Things really couldnt be more dire for frogs, and TBH they should be one of our primary conservation goals. The habitats in which they live are the richest our country has anyway. To help the frogs is to help most things. I agree with chris packham about the panda thing in one sense. Maybe the frog should be the face of the WWF? To protect amphibians is to protect almost the entire inland tropical and temperate natural world.

Its like as if the the british isles had this anti-flood defense and water purification plant that was the envy of the world, it allowed our island to positively seethe with life, it regulated and cleaned freshwater for the whole island, and we destroyed it. Now were arguing about how to save the remnants. The answer is clear really, we have to put the wetlands back, and let the amphibians redistrubute to cleaner shallow waters where predation, disease exposure and vulnerability through immunosuppression is reduced. Soon. Now would be better. Frogs scratching a living in ponds and drainage ditches in close contact situations in dodgy water quality is not the answer.

We need to be creating even artificial wetlands as soon as we can. Its nearly too late, and a wise man never runs with no margin of error. There are acres of farmland out there , laying fallow, nutrient depleted, periodically flooded, used minimally as grazing, a rubbish monotypic environment, we pay farmers subsidies for it, and all around there are small towns experiencing flooding. Its really a no brainer that farmers should be paid off and it returned to the wetland state, to esure safety for our homes, to regulate the water table and hill run-off, to decrease the impact of rivers , and of course to reinstate britains wonderful wildlife.

But no, our societies just want to put more houses up, sell it for carparks and storage warehouses, make flooding worse, spending millions on defense barriers, and dredging, destroying wildlife corridors and havens, when it would actually be more economical and save billions in insurance claims and destroyed property prices to just reinstate the wetland.

The wetland at your door is the water that goes up and down a foot, the river by the door surrounded by farmland and estates built on floodplain is what forces you to get rescued off your roof by helicopter when the rain comes.

Why we arent already doing it on the large scale is just beyond me. Its a total no-brainer.
Originally posted 2 weeks ago. ( permalink )
the longhairedgit edited this topic 2 weeks ago.

dean_area51 says:

It wasn’t that long ago that you could buy ‘giant’ tadpoles in garden centres. These turned out to be American bullfrogs and I knew someone who released them into their garden pond. Although your giant doesn’t actually look as big as the bullfrog tadpoles which were the size of my thumb.
Posted 9 days ago. ( permalink )

steb1 says:

I wonder as well if polyploidism may occur in some of these tadpoles. Polyploidy is where there are more than 2 sets of homologous chromosomes. It is known of in many amphipians, and is a phenomena that has been poorly studied in animals.
Posted 9 days ago. ( permalink )

Cosper Wosper says:

Good point Stephen. Steb1 are you any good with caterpillars (or at least better than I’m with Pipits)? I will post it in the ID thread.
Posted 8 days ago. ( permalink )

Mike_Foster says:

Point well made about decline in wetland.

You’ll perhaps be heartened to note that there is at least some movement towards recreating wetland areas in my local area. Judging by the number of herons we support there must be some prey still clinging on.

It is a total no brainer that allowing water to drain naturally into (if necessary artificial) lakes and marshland is preferable to spending millions on barriers and so on.

Allowing designated no-build lowland areas to naturally flood makes perfect sense for all the reasons you stated. What never ceases to amaze me every year is the utter surprise in the eyes of people who chose to live in the very bottom of a flood plain when their homes are flooded out because we’ve left the river system absolutely nowhere to go.

Wetland with truly wild reed beds is gradually reclaiming some fallow farms near to where I live which is superb for nature watching.

Also, our local municipal golf course has realised that scooping out some pools and leaving them to fill on the low lying margins of their golf course is saving them a fortune on land drainage.
Originally posted 8 days ago. ( permalink )
Mike_Foster edited this topic 8 days ago.

the longhairedgit says:

I am indeed pleased to hear that, and the local authority or group initiating that is to be hugely applauded.

The thing is to get all the others to follow suit. Turning the wetland situation will need to be a country-wide effort.