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Tadpoles and using them to understand brains

Frog pictures

Pictures, diagrams and photographs for your reports, projects, walls...

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This page contains lots of pictures for you to use in your reports, projects, tadpole diaries or whatever you like. Click on the individual photo to print or copy. Please attribute work where appropriate (not needed unless reproduced on line, please refer to creative commons licence rules).


Life-cycle of common frogLife-cycle-label


Life-cycle of common frog banner

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Common frogs in pond- Trevor Rickard

Frogs_in_our_pond_Trevor Rickard


Common frogs mating- Piet Spaans

KONICA MINOLTA DIGITAL CAMERA

KONICA MINOLTA DIGITAL CAMERA


Common frog with spawn- Alan Roberts

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Common frogs mating- Thomas Brown

European_Common_Frog_Spawning_(Rana_temporaria)_Thomas Brown


Common frog- Oh Weh

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Common frog in pond- Alan Roberts

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Child with frog- no attribution

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Common froglet on lily- Nilfanion

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Common froglet- Carol S Cornwall

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Wood frog (Canada)- NatureNorth

Rana-sylvatica-hardingjATmsu-edu


American bullfrog (USA)- John-White

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American bullfrog- Ryan Hodnett

American_Bullfrog_(Rana_catesbeiana)_-_Algonquin_Provincial_Park_Ontario_By Ryan Hodnett Own work


Common frog life-cycle from: Zoological lectures delivered at the Royal Institution, London 1806 and 1807, by George Shaw.

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Common frog eating caterpillar- from Zoological lectures delivered at the Royal Institution, London 1806 and 1807, by George Shaw

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Common frog (Rana temporaria) by William Emerson Damon in “Ocean wonders: a companion for the seaside” (1879)

Image from page 232 of Ocean wonders a companion for the seaside (1879)


Tadpole diagram showing anatomy by Ernst Haeckel (1897)

Ernst Haeckel 1897


Image from “A manual of zoology” (1900)

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Diagrams of common froglet, copied from image from “A manual of zoology” (1900)

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Colour-in frog

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Media credits under creative commons licence

Tadpole swims when touched at *

The details of swimming movements which hatchling Xenopus tadpoles make in response to touch with a fine hair  have been studied by making high speed videos at 200 fps. In these examples touch on the left (*) leads to a bend to the right followed by swimming. Waves of bending travel from the head to tail (at ~ 14 cm per second) and increase in amplitude as they travel along the body. They move the tadpole in the direction shown by the arrows. Swimming speeds at ~ 20 oC range from 4 to 6 cm per second.hatchling tadpole swims when touched at *

Kahn J.A., Roberts A. & Kashin S. (1982) The neuromuscular basis of swimming movements in embryos of the amphibian Xenopus laevis. J. exp. Biol.  99, 175‑184. http://jeb.biologists.org/cgi/reprint/99/1/175

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Adult South Africal Clawed toad Xenopus laevis

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         Xenopus laevis

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What Tadpoles Look Like

Tadpoles can start swimming spontaneously or when they are stimulated but it is just as important that they can stop. This normally happens when their head and cement gland bumps into the surface of the water or some other solid tadpoles swimmingobject like a plant or the side of a dish. This kind of stimulus and the tension in the mucus strand when the tadpole is hanging attached have an inhibitory effect on the tadpole. While hanging, it never moves spontaneously and is much less responsive to stimulation. This ability to keep still may make it more difficult for predators to detect and eat tadpoles. 

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Types of Neurons

There are different types of neurons in a nervous system and they are named depending on their function.

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Interneuron from Xenopus laevis tadpole

Broadly there are 3 main types:

  1. Sensory neurons
  2. Motor neurons
  3. Interneurons 

 

 

 

flex-behaviour

Flexion behaviour of hatchling tadpole in response to skin stimulation (represented by arrow).

When the skin of Xenopus laevis hatchling is touched, sensory neurons are activated, passing on exitation to sensory pathway neurons (interneurons) in the spinal cord, which in turn excite motor neurons, causing flexion behaviour

For more info on research into flexion behaviour click here. 

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Synaptic transmission (blank diagram)

pencil22small_foka.tkPrint and fill in the blank diagram with the key steps in the process of synaptic transmission:

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Resting potential and action potential confusion!

General_Revisionstar

 

The terms resting potential and action potential can be confusing, as they seem to suggest that one is an active process and the other not.

 

Action potentials are actually produced by a passive process- sodium ions diffusing into the axon, causing depolarisation. 

Resting potentials are generated by an active process, which needs ATP. The sodium-potassium pump carries out active transport of ions in and out of the axon to generate a potential difference across the cell and a voltage of -60/70 mV inside the axon.

So even though the axon is said to be at “rest”, an active process involving energy in the form of ATP is actually going on. And even though the action potential sounds like it needs energy, it is actually a passive process.

Make sure you are clear on this!

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Axon, membrane or axon membrane?!

General_Revisionstar

 

Some exam boards prefer you to mention simply the “axon”, others just the “membrane”, or the “membrane of the axon”. 

 

When we are talking about a difference in charge over an area, we always refer to what area that is- for example a potential difference over the axon membrane. 

Some exam boards will prefer you say that the “membrane” or “axon membrane is depolarised”…but others will be happy with just the “axon is depolarised”

Check what is preferred by your exam board and incorporate into your notes links below:

 ⇒Edexcel

AQA

WJEC

OCR

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Exam Board Links

pencil22small_foka.tkClick on the links below to access the specifications for listed exam boards:

 

 ⇒Edexcel

AQA

WJEC

OCR

 

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Toad spawn

Toad eggs are the same size as Frog eggs but are laid in a string, often among weeds in the pond. The string can be more than 1 meter long and contain a double row of eggs. Here is a photo of a small piece from a pond in Hampshire.

A small piece of toad spawn from a pond in Hampshire.

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American Bullfrog

Below is an American Bullfrog. The Latin name of this frog is Lithobates catesbeianus. It is sometimes also called Rana catesbeianus. 

American_Bullfrog_(Rana_catesbeiana)_-_Algonquin_Provincial_Park_Ontario_By Ryan Hodnett Own work

Click here for more information on the American Bullfrog from the ARKive website.


Media credits: American Bullfrog-Ryan Hodnett

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