What is a frog?

Frog spawn in Nowhere WoodIt is late February, the cold weather has moved away and the frogs have moved back in. It’s been a couple of years since they were last here, but here are their newly-laid eggs and the female is hiding beneath the leaf in the top left corner of the photograph. What is a frog and how is it having adventures in Nowhere Wood?

Frogs are amphibians, animals with backbones that live for most of the year on land, but which have to return to water to breed. A female with eggs is popular with males, which compete with each other to get close to her.

When she releases here eggs into the water, the males release their sperm onto the eggs. Fertilisation takes place in the water. The female lays about 2 000 eggs and many of them die. The brown eggs in the top photograph are probably a clutch of eggs that have died.

 

 

 

Inside the egg, the embryo is growing into a juvenile tadpole, feeding on the jelly that surrounds it. It will grow a tail and gills and become a free swimming tadpole. Soon, the tadpole will break free and have to make its way as an independent animal, all of the while developing into the adult frog.

There are dangers in the water: tadpoles become carnivores and will eat each other and there are other predators, too. There is also a real chance that the water in the pond will disappear if we have a prolonged dry spell.

The frogs in Nowhere Wood are having adventures, moving forward into an unknown future, with no certainty of success. Most of these eggs will be eaten and will become food for other organisms; one or two might survive. Most years, frogs return to the water to breed, as frogs everywhere have done for the last 265 million years.

1. The survival of the frogs is not just due to chance. There is competition between male frogs to get close to the females eggs. How does this help to increase the success of the mating?

2. There is also competition between tadpoles for food. How does this help ensure that some frogs will survive to become adults that can reproduce for themselves?

3. What, do you think, is a frog?

Frog news update:

One week on, and the spawn has floated to the edge of the pond and the adds are swollen because they have taken up water. They still look healthy. Fingers crossed for the next stage!

 

 

Early risers!

Spring is coming!

the shortest dayNowhere Wood on December 23rd was silent and still. The wood was in midwinter, at its furthest point from the Sun on its journey through the seasons. At only 7 hours and 49 minutes, this was the shortest day  and darkness ruled the wood. From now onwards the days will get longer by about two minutes each day until midsummer’s day in July.

new born squirrelsThe air was was misty and damp. No birds sang. The only movements were from ten or more baby squirrels running up and down trees, looking for food. The plentiful acorns in the autumn gave their parents the nutrients the needed to produce a special autumn litter.

 

Even by January, the wood had moved onwards and the days were drawing out. Robins sang from high branches of trees, marking out the wood into their territories, preparing for the coming spring.

 

 

Jackdaws and magpies fought for the right to control the high airspaces and the food that the neighbouring houses throw away. The wood was bustling with movement and sound.

 

 

Today is February 1st, the day that the Celtic peoples call Imbolc, the first day of spring. The flowers are opening and the frogs will soon return to our ponds to breed. Look upwards to the sky.

Spring is coming!

  1. Think about the acorns that filled the floor of Nowhere Wood in September. How have they led to the birth of the new squirrels?
  2. What changes have you seen in your neighbourhood in the last few weeks since January?

What is a frog?

Subterranean superheroes

The leaves covering the floor of Nowhere Wood are slowly disappearing in the mild December nights. Fog hangs in the air. The wood is preparing for winter and everywhere is quiet and still. Most of the real action is taking place below the ground, but what is making the leaves disappear?

 

The culprits are earthworms, the little subterranean superheroes that do most of the heavy lifting in Nowhere Wood. There is about 45 million earthworms underground in the wood, with a total biomass equal to about twenty elephants. They are easily the most abundant animal in the wood, but they are so rarely seen.

 

Earthworms tunnel into the soil making the burrows that are their homes. At night, they come to the surface to drag fallen leaves back down into their burrows. The burrows are also perfect homes for bacteria and fungi.

 

 

The bacteria and fungi  feed on the leaves, turning them into nutrients that they use as food. This is humus. Earthworms eat the fungi and the humus-rich soil. As they do so, they glue the soil particles together into small clumps. This improves the quality of the soil, making it a perfect environment for plant roots.

 

Plant roots need plenty water, air and nutrients, all of which are given to the soil by the fungi and earthworms. We can think of earthworms as the soil’s farmers, ploughing the soil for the plants. Without their work, no life could exist in Nowhere Wood.

 

The famous scientist Charles Darwin studied how plants, earthworms and fungi work together to keep woods alive, and he wrote a famous book about it in 1881. He wrote about earthworms: “It may be doubted whether there are many other animals which have played so important a part in the history of the world, as have these lowly organised creatures.”

  1. In what ways do you think that soil is alive?
  2. Think about how the trees, fungi and earthworms work together to keep the wood alive.

Today, Friday 4th December 2020, is World Soil Day 2020. Here is a video celebrating our dependence on soil:

Spring is coming!

A year in the life of a sugar factory

The leaves of plants are everywhere in Nowhere Wood, helping to keep the wood alive. Leaves are organs: collections of living tissues and cells, having adventures in time and space. This is the story of a year in the life of an oak leaf.

Leaves are factories for making sugar from sunlight, water and carbon dioxide from the air. No human factory can do this, which is why we, and all other organisms, are so dependent on plants. Leaves are the producers of food.

In is late November and the cells that will divide to make the new leaf are protected safely inside the scales of the bud. Early in March, when the days warm and get longer, stem cells within the bud start to divide many times, producing all of the cells of the new leaf. To start with, the cells are very small and all look the same.

Soon, the cells take up water and get much larger. They escape the protection of the bud and the new leaf emerges. The new cells no longer look the same: they are on different journeys of development, becoming all of the different cells and tissues that make up the leaf.

 

The leaf is a factory for making sugar. Like any factory, it has a source of energy and transport systems to get the raw materials into the factory.  It also moves the manufactured sugar out to the places in the plant where it is needed. The heart of the factory is the production line where sugar is made. These are called chloroplasts and the leaf has millions of them, all making sugar whenever the sun shines. The Spring and Summer are sugar making seasons.

Gradually, in the autumn, when the days get cooler and shorter, the sugar factories are shut down and abandoned. The chloroplasts lie in ruins as everything useful is recycled back into the branches of the tree. All that remain are the frameworks of cell walls, turning brown as they dry in the autumn air.

 

Finally, the oak tree makes a special layer of cells that separates the old leaf from the stem, and the leaf is ready to fall when the wind blows strongly. The fallen leaves are not wasted, becoming energy stores for the organisms that feed on them. Next year’s buds are forming and wait for spring and the production of new leaves.

If leaves are factories form making sugar, then trees are factories for making leaves.

Everything has its own season in Nowhere Wood.

  1. Think about how the leaf is a factory for making sugar. Where does its energy store come from? How do the raw materials get to the production line?
  2. The production of leaves is sustainable in Nowhere Wood. What do you think this sentence means?

Subterranean superheroes

All change!

When you next look into a mirror ask yourself if you are the same person as you were yesterday. Well, of course you are.

Even people who last met you ten years ago can still recognise you and call you by your name. Although they might add, “My, how you have grown!”

And yet, if we could see under your skin, we would find that you are not the same. One of the biggest mysteries in biology is how we can change all of the time, whilst still staying the same.

Your skin cells live for about two weeks, so every month they are completely replaced. Red blood cells live for about 100 days and about two million are made in your body in every second.

Some of the chemicals in your cells exist for only minutes or seconds.

There is an energy store called ATP, which is needed for muscle contraction. ATP is made and broken down within 15 seconds.  Cells need glucose to make ATP and this explains why muscle cells need a continuous supply of glucose to stay alive. This comes from our food.

Even large organs, like the liver, are replaced regularly. You grow a new liver every year. The cells in the alveoli of your lungs are renewed every eight days. Even the bone cells in our skeleton are replaced every three months. Your entire skeleton is remade every ten years.

 

So, when your friend sees you after ten years and calls out your name, there is not a single part of your body that was the same as when you last met. You have been completely remade and remodelled. And the same is true of your friend.

 

So, how can this be? New cells are made when one cell divides to make two cells. The information in the genome is copied before cells divide, so the new cells always receive the same information as the old cells.

The new cells use this information to grow bigger and to develop. So, you stay the same because of how your new cells use the information in their genomes.

Living organisms are alive because they actively remake themselves. No man-made machine can do this. Which is, perhaps, just as well.

  1. In what ways have you changed in the last ten years?
  2. In what ways have you stayed the same?
  3. Why do need to eat food everyday?

A year in the life of a sugar factory

Climbing the walls

A hundred years ago, Nowhere Wood was a sandstone quarry, and there is still a cliff face at the end of the wood.
How can this hart’s tongue fern grow on a vertical cliff face about two metres from the ground.

That is quite an adventure in time and space. This story explains how this fern can climb walls.


Ferns are an ancient group of plants, first appearing on Earth about 390 million years ago. That’s about 260 million years before the emergence of flowering plants.

Like fungi, another ancient group, ferns produce spores. They are the brown dots on the underside of this fern leaf. Spores are light and float in the air like particles of dust.

One spore floats up to a small crack in the rock face. Rainwater and the decaying remains of a leaf have formed a sticky, jam-like, humus inside the crack.  The spore sticks to the humus and germinates, developing into a tiny little plant, about 10 mm long.

This is a fern, but it is not the mature adult form. It has tiny roots that grow into the humus, drawing nutrients from it.
This small plant is called a gametophyte because it makes gametes for sexual reproduction. Gametes are sperm and egg cells. 


These gametes will come together to make the adult fern on the surface of the tiny gametophyte.

The gametophyte makes many small sperm that swim in the water on the surface of the plant. They swim towards eggs, which are much larger. This photograph shows a fern sperm fertilising a fern egg.

The sperm and the egg join together. A single cell is produced that will grow into the adult fern. Eventually this fern will make spores of its own.

This may sound like a long-winded and complicated adventure, but it seems to work well, because there are so many ferns in Nowhere Wood.

The fern exists in several different forms during its adventure: spores, eggs, sperm, gametophyte and adult plants. What do they have in common?

Each of these forms is made of one or many cells. Each cell contains a nucleus, and inside each nucleus is a genome. Genomes contain information. The information in the genome is the same in all of the different forms of the fern.

The genome contains the secrets of how to be a fern and how to move forward in the next step of the adventure.

  1. The fern exist in several different forms during its adventure: spores, eggs, sperm, gametophyte and adult plants. Think why is important that the genome in every form is the same? 

Life is a relay race

Moving things on

The weather is warm and wet in Nowhere Wood.

These are perfect conditions for growing the fungi that spread  everywhere throughout the soil of Nowhere Wood. Fungi are Nature’s recyclers, feeding on the fallen leaves, fruits and wood.

Fungi feed on the wood of the dead oak trees, turning it into nutrients that provide energy and chemicals needed  to grow new fungal cells.  (These cells form long threads called hyphae). Some fungi can spread out over really large areas, several kilometres wide.

At this time of the year, the fungi are busy ‘ being’.

Then one night, silently and without warning, the fungi do something else.

They produce structures that we call “mushrooms” **.

Mushrooms are  fruiting bodies. They produce thousands of tiny spores.

Spores are small and light. They are carried on air currents to new places in Nowhere Wood, where they will germinate and grow into new hyphae.

Spores have often been found in the filters of jet aircraft flying at the edge of the atmosphere, so some spores can travel right round the world. When fungi produce spores they are ‘becoming’ something new: small, light and mobile versions of themselves.

Then, almost as soon as they arrive, it is all over. The fruiting bodies die and become food for other fungi and bacteria in Nowhere Wood.

This is how it is. The precious molecules are used, recycled and become part of the growth of new organisms. Nothing is ever wasted.



 

  1. All of the atoms in the world were made when the universe began. No atoms have been made or destroyed since then. Imagine what life would be like without Nature’s recyclers.
  2. You are a collection of recycled atoms. Think about how carbon atoms enter and leave your body. [Hint, carbon atoms are found in carbohydrates and in carbon dioxide.]

You can read more about ‘being and becoming’ here.

 

**Some mushrooms are good to eat, others are really poisonous and can kill us. It is hard to tell them apart unless you are an expert, so it is sensible not to touch or eat any mushrooms you find in a wood.

Climbing the walls