|
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.
——————————————————————————————-
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.
|
