Metamorphosis From Tadpole to Frog

References

[1] Combes, D. (2019). Metamorphosing motor networks. Current Biology, 29(12), pp.R557–R561. doi:https://doi.org/10.1016/j.cub.2019.05.005.

[2] Callery, E.M., Fang, H. and Elinson, R.P. (2001). Frogs without polliwogs: Evolution of anuran direct development. BioEssays, 23(3), pp.233–241. doi:https://doi.org/10.1002/1521-1878(200103)23:3%3C233::aid-bies1033%3E3.0.co;2-q.

[3] Coots, P.S. and Seifert, A.W. (2015) ‘Thyroxine-Induced Metamorphosis int he Axolotl (Ambystoma mexicanum)’, in Kumar, A. and Simon, A. (eds.), Salamanders in Regeneration Research: Methods and Protocols, Methods in Molecular Biology, vol. 1290.

[4] De Groef, B., Grommen, S.V.H. and Darras, V.M. (2018). Forever young: Endocrinology of paedomorphosis in the Mexican axolotl (Ambystoma mexicanum). General and Comparative Endocrinology, 266, pp.194–201. doi:https://doi.org/10.1016/j.ygcen.2018.05.016.

[5] Gilbert, S.F. (1997). Developmental biology. Sunderland, Mass.: Sinauer Assoc.

[6] Spencer, K.A., Belgacem, Y.H., Visina, O., Shim, S., Genus, H. and Borodinsky, L.N. (2019). Growth at Cold Temperature Increases the Number of Motor Neurons to Optimize Locomotor Function. Current Biology, [online] 29(11), pp.1787-1799.e5. doi:https://doi.org/10.1016/j.cub.2019.04.072.

[7] Van Allen, B.G., Briggs, V.S., McCoy, M.W. and Vonesh, J.R. (2010). Carry-over effects of the larval environment on post-metamorphic performance in two hylid frogs. Oecologia, 164(4), pp.891–898. doi:https://doi.org/10.1007/s00442-010-1728-8.

[8] Dash, M.C. and Hota, A.K. (1980). Density Effects on the Survival, Growth Rate, and Metamorphosis of Rana Tigrina Tadpoles. Ecology, 61(5), pp.1025–1028. doi:https://doi.org/10.2307/1936818.

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The Digestive System

 

The digestive system is modified to account for the change of the herbivorous diet of the tadpole to the carnivorous diet of the frog.

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The Skin

 

The skin adapts for the change from a purely aquatic lifestyle to an amphibious lifestyle.

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The Reproductive System

 

The urogenital system develops to allow for reproduction in adulthood.

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The Skeleton

 

The skeletal structure develops to accommodate the change from tail swimming to using legs to move around. The skull also needs to be remodelled for a frog's change in vision.

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The Nervous System

 

A tadpole sees from eyes that are positioned on opposite sides of the head. During metamorphosis, the optical nerves develop to accommodate a frog's binocular vision, where the eyes are positioned at the front of the head.

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1. Mating and Laying Spawn

 

Male and female frogs go to ponds in the winter. They mate in the spring, and the female lays big clumps of eggs.

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2. Frog Spawn

 

Frogs eggs are called frogspawn. Each round black egg is about 1 mm wide and is surrounded by a blob of jelly. Other animals produce spawn as well, which you can look at here.

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3. Maturing Frog Spawn

 

After a few days, the eggs begin to grow into tiny tadpoles inside the jelly.

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4. Hatchlings

 

Then the tadpoles hatch! They are about 5 mm long and they can’t swim (yet). They can bend their body from side to side using special muscles along their trunks and tails.

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5. Young Tadpoles

 

When their tail is big enough, they swim off into the pond to start to feed. At first they have gills (the pale protrusions from the head region in the left photo) so they can breath underwater like fish. Young tadpoles feed by grazing the surface of pond weeds and also eating tiny floating plants called algae.

Click here to play a tadpole feeding game called Taddypole!

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6. Maturing Tadpoles

 

Later they develop lungs and can swim up to the surface of the water to breath. The gills are absorbed back into their bodies and eyes develop. Older tadpoles are then able to feed on small animals like young insects.

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7. Mature Tadpoles

The next stage in development is to grow back legs. Tadpoles during this stage need to eat meat in order to get the proper nutrients to grow.

If you are looking after tadpoles, be careful as they can eat each other if you don't give them meat to eat! Click here to learn more about how to look after tadpoles as pets.

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8. Froglet

Finally, tadpoles grow front legs and their tail shrinks until it almost disappears. This is when they climb out of the pond and start living on dry land. Small frogs are commonly called froglets.

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9. Adult Frog

The little froglets will stay by the pond and slowly grow over the summer, eating small insects and worms. They will hibernate just like other adult frogs in damp spots near ponds from autumn until the next spring.

After four years, the new frogs will become adults and will be ready to mate and begin the cycle again.

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Copy - 9. Adult Frog

The little froglets will stay by the pond and slowly grow over the summer, eating small insects and worms. They will hibernate just like other adult frogs in damp spots near ponds from autumn until the next spring.

After four years, the new frogs will become adults and will be ready to mate and begin the cycle again.

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