Very early indeed.
Frogs & toads are a fascinating analogy showing in part the evolution of advanced organisms on this planet from the primitive aquatic stage to when animals first started to leave the water & colonise the land.
External fertilisation of the eggs in water, (The cell division & later development of the black embyro can be seen with the naked eye). when the tadpoles emerge they have external gills (primitive) then transform those into internal gills & later on develope lungs. At first after breaking free from the timed decomposition of the Jellified egg coverings they will feed on their egg sacs.........Then will start off as vegetarians & after 6 weeks or so will completely transform their digestive tracts & become carnivores. Now from being a basic fish like organism, all be it with some advanced technology, they start to grow legs. Both front & back legs grow at the same time but the front legs grow under the skin to maintain the taddy's hydrodynamics until they are fully formed, then will burst out. The tadpoles at this stage, in natural conditions, will start to hang around in the shallows preparing for their ultimate evolutionary miracle...............during the last week of their development, they will reabsorb their tails ( they can't eat as thier mouth & jaws are undergoing a transformation ) then on D-day will moult ( on shedding their tadpole suits they become perfect little frogs) & leave their watery nursery to go & explore the land.
Phew!!!! I don't know about you guys but seeing millions & millions of years of evolution when a frog starts it's existance as a primitive aquatic larvae with external gills into an advanced four legged, lung breathing terrestrial vertibrate just blows me away...............& in only 3 months ( depending on temperature of course)
Incidently tadpoles have a chemical weapon 'up their sleeves' so to speak. When the earliest of them start to transform into carnivores & there isn't sufficient meat available, they will release a stress hormone into the water which will inhibite the development of the later emerged tadpoles,(in stagnant water, rivers are a different matter) who will complete their cycle the following year should they survive. When meat is in shortage, dead fish etc. they are capable of transforming into pack hunters & will gang up & devour fish, water snails or even other tadpoles depending on what's available. Devour is prehaps too strong a word as they only have small mouths a rasp like teeth so prehaps 'scraping' would be a better term. the result is the same though.
Hopefully you'll see frogs & toads in a different light from now on.
Very early indeed.
Frogs & toads are a fascinating analogy showing in part the evolution of advanced organisms on this planet from the primitive aquatic stage to when animals first started to leave the water & colonise the land.
External fertilisation of the eggs in water, (The cell division & later development of the black embyro can be seen with the naked eye). when the tadpoles emerge they have external gills (primitive) then transform those into internal gills & later on develope lungs. At first after breaking free from the timed decomposition of the Jellified egg coverings they will feed on their egg sacs.........Then will start off as vegetarians & after 6 weeks or so will completely transform their digestive tracts & become carnivores. Now from being a basic fish like organism, all be it with some advanced technology, they start to grow legs. Both front & back legs grow at the same time but the front legs grow under the skin to maintain the taddy's hydrodynamics until they are fully formed, then will burst out. The tadpoles at this stage, in natural conditions, will start to hang around in the shallows preparing for their ultimate evolutionary miracle...............during the last week of their development, they will reabsorb their tails ( they can't eat as thier mouth & jaws are undergoing a transformation ) then on D-day will moult ( on shedding their tadpole suits they become perfect little frogs) & leave their watery nursery to go & explore the land.
Phew!!!! I don't know about you guys but seeing millions & millions of years of evolution when a frog starts it's existance as a primitive aquatic larvae with external gills into an advanced four legged, lung breathing terrestrial vertibrate just blows me away...............& in only 3 months ( depending on temperature of course)
Incidently tadpoles have a chemical weapon 'up their sleeves' so to speak. When the earliest of them start to transform into carnivores & there isn't sufficient meat available, they will release a stress hormone into the water which will inhibite the development of the later emerged tadpoles,(in stagnant water, rivers are a different matter) who will complete their cycle the following year should they survive. When meat is in shortage, dead fish etc. they are capable of transforming into pack hunters & will gang up & devour fish, water snails or even other tadpoles depending on what's available. Devour is prehaps too strong a word as they only have small mouths a rasp like teeth so prehaps 'scraping' would be a better term. the result is the same though.
Hopefully you'll see frogs & toads in a different light from now on.
Are you showing us that you're a Sun reader or have you kidnapped the spawn & hoping for a ransom ?