Clownfish

Clownfish (sometimes known as anemone fish) are related to damselfish but are noted for being brightly coloured with contrasting bands across the body. The name comes from the resemblance to a clown’s facial make-up.

They are found on coral reefs in the Indian and Western Pacific Oceans.

Apart from their appearance (which makes them popular as aquarium fish) their most remarkable feature is the symbiotic relationship they have with venomous sea anemones that feed on fish of other species.

The clownfish has mucus on its skin that makes it immune to the sting of the sea anemone which means that it can hide among the tentacles of the many anemones that populate coral reefs. In turn, the clownfish’s bright colours attract other fish that then become prey for the anemones.

© John Welford

Carnotaurus

Carnotaurus was a therapod dinosaur that lived during the Cretaceous era about 75 to 70 million years ago. Fossils have been found in Argentina, the first discovery being made in 1985.

Carnotaurus was a medium-sized dinosaur at 8 to 9 metres in length, weighing around one ton.

The skull was relatively tall from top to bottom but short from front to back, which accounts for its name which translates as ‘meat-eating bull’ in reference to the appearance of its head.

Carnotaurus had two small horn-like projections above the eyes, and a row of scales along the spine that produced a series of regularly placed lumps.

Carnotaurus was similar to Tyrannosaurus in that it had tiny ‘arms’ for which the use is difficult to envisage – they would have been too short to reach the animal’s mouth.

Although Carnotaurus was clearly a meat-eater, its teeth and jaws were not particularly large or powerful. This suggests that it would have preyed on smaller plant-eating dinosaurs.

© John Welford

Buttercups in Great Britain

There are four species of buttercup that grow wild in Great Britain, although one of them (celery-leaved) is relatively rare.


Meadow buttercup (Ranunculus acris)

The meadow buttercup can grow up to 36 inches (90 centimetres) in height and prefers damp conditions. It has a large number of leaves, which are divided into anything from two to seven lobes, and the small flowers, which can vary in shade from bright to pale yellow (or even white) are evident from May to July and can last right through the summer.

The buttercup is poisonous to cattle, which is one reason why the meadows in the picture (in Wensleydale in the Yorkshire Dales) are not grazed at this time of the year. However, cows tend to avoid eating them anyway, which is just as well.

Children like to pick buttercups and hold them under each other’s chins to see if the yellow reflects on the skin. If it does, this is supposed to show that the child in question likes butter!

In former times buttercup roots were ground up with salt as a treatment for plague – they were said to cause blisters that drew out the disease. Fortunately, there is little call these days for testing whether the method works.

Another use for buttercups was to hang them in a bag round the neck, as a cure for lunacy. Nowadays one might think that wearing a bag of buttercups might be a symptom of the ailment rather than its cure!


Creeping buttercup (Ranunculus repens)

This is the buttercup variety that you do not want to get in your garden! It sends out runners in all directions that, every few inches, establish new plants and make it difficult for plants such as grass to get a foothold. Unless you are able to get every scrap of creeping buttercup removed, your lawn can quite easily be ruined.

On farmland the effect can be even worse because cattle will avoid it when grazing – it is unpleasant to the taste – and take the grass instead. This only leaves more room for the creeping buttercup to spread into. If the land is ploughed, the buttercup plants can easily regenerate many times over from the pieces that the plough has cut up.

The plant can be short or tall, depending on soil conditions. It can therefore be a ground-hugger, only two inches (five centimetres) high, or grow up to 20 inches (50 centimetres) in height. The hairy leaves, on long stalks, have three lobes with the central one being much larger than the other two. The yellow flowers, which are single or in clusters, can be seen from May to September.


Bulbous buttercup (Ranunculus bulbosus) (pictured above)

This is similar to the meadow buttercup but each stem has a swollen base and each leaf has a stalked central lobe. The sepals bend down rather being close to the petals. Bulbous buttercups flower earlier than meadow buttercups, being evident from March to June, and they prefer drier conditions to those favoured by the meadow buttercup.


Celery-leaved buttercup (Ranunculus sceleratus)

Not only is this species less common than the others, it is also not so easy to spot given that its flowers are much smaller and it does not throw out runners. It has hairless lower leaves without a stalked central lobe. The fruit forms an elongated head.

© John Welford

Brabant heavy horse

This is a Brabant heavy horse, giving a demonstration of timber hauling.

The Brabant is also known as the Belgian Heavy Draught, being an ancient horse breed with a pure bloodline. It is noted for its muscular neck, powerful shoulders, compact body and short legs. It is known to be easy-going and amiable. Standing at 16-17 hands and weighing about a ton, the Brabant was traditionally used as a draught horse on farms, but numbers have fallen drastically with the growth of mechanisation.

However, heavy horses now have a new role to play as they have been found to be ideal for use in forests when tree trunks need to be transported along narrow forest paths or across terrain where the use of vehicles is impractical. A horse such as this can haul a ton weight across level ground and remove 25 tons of timber during a working day.

Needing no fuel other than food, and producing nothing more offensive than manure at the other end, the future of heavy horses for forestry use seems assured, given that they cause no damage and can access all sorts of difficult places.

© John Welford

The evolution of birds

It is generally believed that birds evolved from reptiles and are the nearest living creatures to the dinosaurs, the last of which suffered extinction some 65 million years ago. However, the exact evolutionary route from Tyrannosaurus Rex to house sparrow is not so easy to work out.

Dinosaurs to birds

It is known that the skies 150 million years ago were patrolled by massive winged reptiles called pterosaurs, but these were not the ancestors of modern birds. For one thing, they did not have feathers and, for another, they belong to a different branch of the evolutionary tree.

Dinosaurs, by which is meant land-dwelling reptiles of the Triassic, Jurassic and Cretaceous eras (251 to 65 million years ago) can be divided into two main branches, the Saurischians and the Ornithischians, based on their hip structure. Confusingly enough, birds evolved from the first-named group, not the second. They are therefore more closely related to carnivorous reptiles such as Tyrannosaurus and Velociraptor than herbivores such as Iguanodon and Stegosaurus.

Archaeopteryx

The idea that birds evolved from dinosaurs was first proposed after the discovery in Germany in 1861 of the fossilised impression of a creature from 150 million years that was clearly a reptile but which also had feathers. This was named Archaeopteryx (meaning “ancient feather”) and was widely hailed as being an intermediary between dinosaurs and birds, given that the structure of its bones and the arrangement of the feathers made it entirely possible for Archaeopteryx to fly. It would have been about the size of a modern raven. The discovery came only two years after the publication of Darwin’s “The Origin of Species” and was seen as confirmation of Darwin’s conjecture that species could evolve into new ones.

However, there are doubts over whether Archaeopteryx was the direct ancestor of modern birds, or whether that honour belongs to a creature related to Archaeopteryx that has not, as yet, turned up in the fossil record. Another complication has been the discovery of fossils (in China in 1998) of dinosaurs that had feathers but clearly were not suited for flight.

The suggestion is therefore that feathers evolved for a purpose other than enabling a creature to fly. It is quite possible that the original function of feathers was to provide insulation or to attract mates, and that Archaeopteryx and its relatives and descendants adapted them as a means of achieving flight.

One theory is that an ancestor of Archaeopteryx might have hopped along the ground and grabbed insects out of the air. Those that jumped higher would get the most insects and the ability to flap the wings and take off altogether evolved from that activity.

So where might birds have come from?

The fossil record includes later specimens that show how early bird species might have developed. These include Ichthyornis and Hesperornis from the Upper Cretaceous (100 million years ago).

The virtual disappearance of the dinosaurs 65 million years leaves open the question of how the bird ancestors managed to survive, especially if the reason for the disappearance was a strike on Earth by a large meteor or small asteroid, resulting in worldwide destruction of plant life due to vast dust clouds preventing proper sunlight from reaching the surface for a number of years. It has been suggested that the small size of proto-birds might have been a factor, coupled with the insulation provided by feathers and their ability to fly to whatever food sources were available.

In the post-dinosaur world the evolution of birds took off in many directions, aided by the fact that winged flight enabled birds to reach locations that presented many different ecological challenges that in turn led to further evolutionary development. By 60 million years ago the ancestors of modern herons, vultures and kingfishers are known to have been living, and most of the bird families in existence today are known to have evolved by the end of the Miocene (11 million years ago).

Continuing evolution

Evolutionary changes are still taking place in bird populations. Charles Darwin noted how the finches of the Galapagos Islands had evolved different feeding strategies to cope with the variety of food available between different islands within the same group, and those changes would have taken place relatively recently in the geological timescale, given that the islands themselves had only emerged from the ocean within the past four million years.

An even more recent example of bird adaptability leading to species evolution is that of the feral or urban pigeon which has developed characteristics that are quite distinct from its rural cousin the woodpigeon, due to having abandoned the cliffs of coast and mountain for the manmade cliffs of city buildings.

What all this shows is that evolution is a process that affects all living creatures, as it has done ever since the only life forms on the planet were viruses and bacteria.

© John Welford

Bhutan Glory butterfly

The Bhutan Glory butterfly is found in the mountainous areas of central Asia, at altitudes of up to 3000 metres. Its preferred habitats are meadows and forests.

The wings of the Bhutan Glory measure 9-11 centimetres across. They have dark front wings but bright orange on their back wings, which are normally hidden by the front wings. If threatened they will rapidly open and close their wings to reveal the bright patches, in the hope of scaring any predator away.

Their other main defence mechanism is to feed on poisonous plants, such as the Indian birthwort plant, and absorb the poison into their bodies.

The Bhutan Glory is a protected species due to its great rarity.

© John Welford

Apollo butterfly

The apollo butterfly is one that not many people have seen, due to its remote habitat, and it is also an endangered species.

Apollos are found in mountainous and hilly regions in central Europe, Spain, Scandinavia and Asia. They have furry bodies as protection against the cold at high altitudes.

The food plant of the Apollo is stonecrop. The female butterfly lays hundreds of eggs in July and August and these hatch out in August and September. However, the hatching is only partial, because the caterpillars will stay inside the eggs until the spring. They will then moult up to five times before they are ready to pupate.

Efforts are being made in many places to protect these rare and very attractive butterflies, which have a wingspan of 5-10 centimetres. Habitats are being managed and the use of insecticides reduced in their breeding areas.

© John Welford

The antler cycle of the fallow deer

Antlers are grown by the males of all species of deer, although reindeer cows also grow them. They are used mainly as weapons, particularly during the rutting season when stags fight for control of a harem of does. Antlers are not the same as horns in that they are bony growths that drop off and are renewed every year, unlike the horns of other mammals that are permanent features. The cycle of growth, shedding and re-growth varies between deer species and their location; the cycle described here is that of fallow deer in Great Britain.

Fallow deer fawns are born around June, and in March of the following year male fawns develop stalks, known as pedicles, from which the antlers will later grow. Although antlers are cast and then re-grow, the pedicles are permanent features. The fawn’s first antlers start to appear at the tops of the pedicles in May.

The antlers, which are straight, slender spikes with branches appearing only rarely in the first year, grow rapidly and are complete by late July. The antlers are covered by a hairy skin called velvet which contains blood vessels that supply oxygen and food to the bone as it grows.

When the spikes have finished growing the velvet shrivels, being discarded by the buck as it rubs its head against tree trunks. By mid-August the antlers will be dead tissue, but they stay in place until the following spring.

The first antlers are cast in late May, usually one at a time with an interval of a few days between the castings. There will be some bleeding from the pedicles when the antlers break off, with scabs forming shortly afterwards.

New antlers start to grow within one or two weeks, and growth is rapid, as with the original pair. However, by early July the second pair will show signs of branching into two “tines” on each antler, one pointing forwards and the other backwards. The forward-facing tine will only grow a small amount, developing into a sharp point curving upwards, but the backward-facing tine, known as the main beam, will develop into a much more substantial structure.

Throughout July and August the main beam will grow and several more tines will then branch off it. The ends of the antlers will broaden out to form blades with spikes growing off them, looking not unlike holly leaves in general shape.

In late August, after the growth is complete, the velvet will be shed, as in the first year, with the animal using trees to help rub it off. However, because of the much greater amount of velvet involved, the result will look untidy for several days as bits of bloodstained velvet hang off the antlers. Observers may think that the young stag has been injured in a fight as blood drips off his antlers, but this is not usually the case.

By the end of August all the velvet will have gone and the antlers will be clean and hard, remaining in place throughout the winter until the process begins again in the following spring.

Each new pair of antlers will be larger and heavier than those of the previous year, with the blades becoming broader and the antlers curving upwards and outwards. A mature buck has antlers up to about 20 inches (50 centimetres) in length. This process continues into old age, so it is possible, up to a point, to judge the relative ages of stags within a herd. However, it is difficult to determining a mature stag’s age accurately from its antlers alone. There are also many variations in size and shape between the antlers of bucks of the same age.

© John Welford

Bank vole

The bank vole (Clethrionomys glareolus) is a common animal found in the British countryside. It is 9-12 centimetres long and weighs up to 45 grams. When seen, a bank vole can be mistaken for a mouse, but it is plumper, has smaller ears, and a short furry tail. Their short fur is brown on the back and greyish on the sides.

Bank voles live in woodlands, hedges, gardens and parks, and their food consists of fruit, nuts and small insects. In suburban gardens they sometimes visit bird tables.

Bank voles are an important part of the rural food chain as they are prey to stoats, weasels, foxes and birds of prey.

Females give birth to litters of between three and eight young. They become sexually mature when only five weeks old, but their vulnerability to predators means that most bank voles do not live to be older than five months. Fortunately for the species, their fecundity as breeders means that there is no shortage of bank voles in Great Britain!

© John Welford