IT has always seemed a shame to me that the wonders of nature are taught only to small children, then taken for granted ever after. I don’t know if schools still have a nature table, as we did, or have nature study lessons, or put horse chestnut branches in a jar to watch the sticky buds bursting.
We can revisit our early school days via the marvel of YouTube and learn all over again the amazing stories of the natural world. I thought it would be interesting to see what I could turn up on common frogs (Rana temporaria) with photographic techniques that were unheard of when I was at school. I haven’t seen a frog in the wild for decades but I think that is probably more to do with my giving up turning over stones than to a major decline in their numbers. There has been a nasty and lethal virus around since the 1980s but according to the charity Froglife populations tend to recover after it passes. https://www.froglife.org/what-we-do/disease-ranavirus-2/ (To prevent the spread of the virus it is important to return any tadpoles to the pond where they were collected, and not to move spawn, tadpoles or frogs between ponds.) A 17 per cent decline in regular sightings was recorded between 2014 and 2018; this may be to do with the insatiable devouring of the countryside for housing. https://conservativewoman.co.uk/notes-from-the-sticks-how-green-was-my-valley/ If they do lose their home ponds they often colonise garden ones. Anyway they are not considered to be under threat.
Let’s start with the mating season. Frogs are solitary for most of the year, living in damp cool places up to 500 yards from fresh water. In early spring, prompted by a combination of day length and temperature, they congregate in ponds and the males compete for females by croaking.
When a male attracts a female he clasps her under the arms and fertilises the eggs as the spawn emerges.
There may be 1,000 or 2,000 eggs in a batch of spawn, and dozens of batches in a pond, but there is no need to remove any because they are a tasty treat for all sorts of creatures including fish, newts, birds, dragonfly larvae, hedgehogs and even larger tadpoles. Only a tiny fraction will make it to adulthood.
The eggs take about 11 days to hatch, longer if it is cold.
Here is a timelapse film of the development (for some reason the makers of wildlife films feel compelled to add loud music – I can’t bear the Attenborough oeuvre for this reason, leaving aside the climate change hectoring).
After around 12 weeks the astonishing process of metamorphosis begins. The tadpoles grow back legs, then front ones. They turn carnivorous, eating tiny water creatures and carrion. The most extraordinary thing of all is that they develop lungs so that they can breathe air, while their gills, which abstract oxygen from the water, wither away. So for a while (I haven’t been able to discover exactly how long) the two very different respiration systems are in use at the same time. It is as almost as huge a jump as a fish turning into a man. The tadpole’s tail shrinks and at the same time its head and body start to look like a frog. This film shows the process. (It covers egg development but it is worth watching the two versions.)
Slow-motion photography enables us to see how a frog catches its prey (insects, spiders, slugs and worms). Its tongue is extremely soft and sticky and is hinged at the front. This is an American frog but the principle is the same. Yum.
Slo-mo is also great for jumping frogs. See my previous note about music.
This frog executes a very neat dive.
PS: While roaming around YouTube I came across this guide to making an origami frog which can jump. I could no more do it than fly to the moon, but this chap makes it look easy.
The common twayblade orchids are now flowering about halfway up the stems. Here is last week’s picture:
And this was on Thursday (I did say they are not very spectacular!):
The gunneras are going strong. This is last week’s picture:
And this is yesterday. There is a flower spike visible on the left hand plant now and the frost-damaged leaves are dying back.