The Frog and Pond Diary

March - 2002

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1 March - A bright and sunny start to the month, but a touch of ground frost indicated a cold night for the frogs and there were very few in sight first thing this morning.

Despite this there was a certain amount of splashing as I approached the pond at 8am, and the area covered by spawn has continued to grow overnight. The picture shows the shallow end of the pond. It measures about 5ft (1.5m) across by 4ft (1.2m) and is now covered by an almost continuous layer of spawn.


As the day progressed, so did the orgy of spawning. In this picture (taken at 2.30pm) you can see the feet of the female at the centre of the writhing scrum of males. It's no wonder that they sometimes drown as a result of these encounters.

Click on the images for larger versions.



2 March - The spawn met its first big challenge last night as the air temperature fell below 0C and the pond and spawn was covered with a thin but continuous layer of ice.

There was not a frog to be seen at 8am, just the ice patterns over all the water surface reflecting the morning light.

There was some activity in the day, once the ice melted, but it was on a much lower scale than the last few days.


3 March - A milder start to the day meant lots of frogs in sight again. However, the level of activity has somewhat diminished now and there seem to be a lot of frogs waiting around for something to happen. The croaking continues, but the volume has been turned down.

There is still the surge of hopeful males when something moves, but no sign of scrums today.



While most seem to have moved to the weeds of the open water, some frogs still move about amongst the spawn, and the whole mass seems to wobble when ever one of them tries to move about on it.

If you take a close look at the large version of this image you may see that some of the frog embryos have already developed from their original spherical shape.


4 March - All over the pond now are pairs of eyes like these, gazing in all directions. Are they all waiting for another mate to arrive? Or is it time to rest after all the exertions of last week?

Some at least seem to be still interested in anything that moves, but there is no longer the enthusiasm of last week.

Many are obviously alert to predators as they crash dive whenever I walk near the pond.


While the frogs are obvious to anyone looking at the pond, the newts are, in their more secretive way, becoming much more active now. These pictures were taken last night around 10pm, when I saw at least a dozen newts.

The males (top image) are especially wary of torchlight, although this one stayed put long enough for me to capture an image that shows that it has developed its breeding crest.

You can see the difference in the hind feet of the male and female newts - it is probably best to click on the picture for a larger version.

5 March - I could not resist yet another frog picture today, sunshine, and mild conditions have obviously renewed optimism among the hords in the ponds. Croaking levels are high once again and I have failed to make an accurate count of the heads above the water, and sunning themselves on the bank.

Last night at around 10pm I did see two scrums in action around some unfortunate females, and the picture shows one at lunchtime today.

It shows a female (with the bulging yellow underside) sandwiched between two males who are clutching her tightly with their front legs, while her legs are outstretched, helplessly. Click on the picture for a larger version.

6 March - Tonight, at 9pm the pond was exceptionally quiet. There were a couple of dozen frogs at the surface but I could see a lot submerged. There was no croaking to be heard and just the occasional flurry of movement by them.

In contrast, the newts are very busy. It is difficult to count them as they keep on the move and often disappear under the pond plants, but I estimate that I saw between twenty and thirty. There are definitely more than I saw last year.

Every so often you can hear a quiet 'plop' and see a bubble left on the surface where one has come to the surface to take a quick breath. The picture shows a male doing just that. The small grey shape seen about half way along its body is a small flatworm that was gliding upside-down along the water surface. Click on the picture for a larger version.

At 10.30pm, and with the outside temperature at 11C there are lots of frogs at the surface and a bit of croaking going on!


7 March - Well, last night's croaking must have reaped its rewards, as there were two fresh clumps of spawn this morning. The picture shows a bit of it. The insert shows how one embryo is already showing the first cleavage of the fertilised egg into two cells. I will try to take some more close-ups as development progresses.

While the spawn grows, sunshine and mild temperatures (13.5C at 11am) have encouraged the frogs to practise their choral croaking again. Quite a few have now migrated back to the small pond, and are starting to sit out on the sides.

An update at 5.30pm - I have just taken this second image of the embryo pictured above (at 10.15am - seven hours before this one). The difference is amazing.

I believe that the embryo has now reached the stage of being known as a Blastula. If I am correct, the smaller cells seen at the top represent the animal hemisphere from which the tadpole will develop, while the larger cells of the lower hemisphere are yolk-containing cells.


8 March - This image shows the embryo at 8am this morning. You can see how the yolk cells are forming a lighter patch at the bottom of the image.

In the pond there is still some croaking going on, but the frogs are nowhere so eager to chase each other today, and I can see no new spawn.



One characteristic sight here through the summer months is tightly packed groupings of frogs on the bank or on a rock in the small pond. I have just spotted this group of four taking advantage of today's good weather - sometimes there are a dozen or more gathered like this, especially on a sunny day.

There will not be a diary entry tomorrow.



10 March - Back from South Wales this afternoon, my first task was to get this image of the frog embryo. Surface detail is harder to see now as the cell structure starts to get more complex. I should have said earlier that the embryo measures just under 2mm across.

The insert shows an enlarged bit of the surface , showing it to have a dimpled texture, presumably the outer layer of cells.

If you click on the image you can see a larger picture of the embryo, showing this texture.


Outside, on a very windy day (temp 10C), I can only see one frog at 3.30pm.

11 March - The frog embryo is now showing the firsts signs of the development of structure.

Look carefully at the top half and you should see raised ridges running upwards in an arc from the left side towards the right. A look at my old biology text-book and its diagrams suggests that these mark the development of the Neural folds. The area between the folds would be the medullary plate, from which the brain and spinal cord will form. The diagram in my book indicates that, if what I have said is correct, the top right of the image represents the front or anterior of this development.

If you click on the image you can see a larger picture of the embryo, showing this growth and the dimpled cell texture more clearly.

In the pond it has been an active day again with lots of croaking and two new patches of spawn! More and more frogs are now spending time on the banks of the pond.


12 March - Today's embryo update sees the Neural folds much more pronounced now, with shapes appearing at the anterior (head) end. The left-hand insert shows the folds clearly.

The left and right folds will gradually fuse together to enclose the Neural tube. In this tube the tadpole's spinal cord and brain will develop.

If you click on the image you can see a larger picture of the embryo, showing this growth more clearly.

13 March - The frog embryo is really taking shape now. The right hand image is the one I have been following. If you look carefully about half way along the 'back' of the embryo you can see some banding (at right angles to the Neural fold). These are the myotomes - the embryonic structures from which the body muscles are formed. Near the right end of the embryo, the part that looks like an elephant's ear(!) is called the mandibular arch.

The left image shows how the Neural folds are now linked up

If you click on the image you can see a larger version.

2002 Frog & Pond Diary Index..............LLast Month....................March (part 2)