Month: April 2013

"a can of worms"

"a can of worms"

nao

My daughter asked me the other day if you cut an earthworm in two will it grow back again?  And will you have two worms?  Suddenly the whole family is in on the act with talk of geckos tails and why we can’t grow back a limb.  So to dispel a few myths and legends I thought I’d take a look for this weeks blog!

photo credit: schizoform via photopin cc
photo credit: schizoform via photopin cc


CAN YOU CUT A WORM IN HALF AND GET TWO WORMS?

The short answer is NO, so please don’t go trying!  It is true that the anatomy of the earthworm is very different to our own and if part of a worm is cut off, one part may survive.  The part that can survive is the “head” end. First let’s look at some of the unusual features of the inside of an earthworm.

ANATOMY OF AN EARTHWORM

Image credit: the weather report

The earthworm’s body is made up of segments called annuli.  These segments are stuck together just like a series of rings all lined up; each segment contains little bristle like hairs called setae and these allow the earthworm to move.  Earthworms are invertebrates meaning they don’t have any internal “boney” skeleton.

The earthworm does not have one heart as we do… it has FIVE!  These hearts help pump the blood through the worm’s body.  The worm needs oxygen just as we do but it has no lungs to fill with air, instead it has time pores on it’s skin which absorb oxygen from outside it’s body.  In order for this to happen the worm needs to keep it’s body moist, which is why they often feel a bit slimy.  Too much moisture though and the worms can drown; when it rains earthworms will move closer to the surface to prevent them from drowning!

Earthworms have a “head” and a “tail” but no eyes, ears or nose, so they can’t see, hear or smell as we can.  However their skin is covered with sensors for light and movement so thy can react to too much light (sunshine) or movement (rain falling or soil being disturbed by digging predator).

SO WHAT HAPPENS IF WE CUT AN EARTHWORM IN TWO?

Firstly, cutting up earthworms or any other creature is a very cruel thing so please don’t do it!  However if an earthworm’s body was to be cut into two parts its survival would depend on a number of factors:

  • Where in the body is the earthworm cut?  The earthworm would have a better chance of surviving if it’s body is cut closer to it’s tail end.  This end does not contain the vital organs.  Research by Dr. Thomas H. Morgan (1901) found that the head end of the earthworm may survive if the head end contained at least 16 segments.  It is possible that some of the tail end will even be regenerated. Some repair and regeneration is also possible at the head end, but usually only within a small number of segments.
  • Chance of infection:  the earthworm can pick up a bacterial infection just as we can.  If the earthworm can seal the cut or regenerate the segment before infection sets in it has a better chance of surviving.
  • The speed at which the earthworm heals:  regenerating part of the body would require an awful lot of energy for the earthworm, the quicker it can heal the quicker it can get back to eating and refuel its body.  If the earthworm does not have enough energy to complete the process it will die.

THE ROLE OF EARTHWORMS IN OUR GARDENS

The earthworm is often called “nature’s plough” as it digs through the soil , turning and rotating as it goes.  Earthworms are herbivores, they feed on leaves, root and other decaying plant matter. The earthworm deposits this matter through out the soil through its faeces.  An earthworm can eat up to one-third of its own body weight in a day!

The burrowing of earthworms helps the soil in two ways, it allows air and water into the soil through the channels it forms and it moves different layers and types of soil around, distributing nutrients and making the earth more fertile. Although earth worms often stay close to the surface of the soil they can burrow down as deep as two metres.

EXPERIMENT: Make your own wormery

A wormery (or worm farm) allows us observe the work that worms do within our soil.

  • Fill a large see-through container with alternative layers of soil and sand.
  • Put a layer of leaves and vegetation on the top.
  • Add enough water to keep the soil damp.
  • Collect some worms and add them to your wormery.
  • Cover the outside of your bowl with a large piece of card or paper to block out the light.
  • Put your wormery in a safe place and check on it every day – remember to keep adding some water to keep the soil moist.
  • You sould notice very quickly that the different layers of soil and sand are getting mixed together, the work of the industrious worms.
  • Remember to keep adding leaves and vegetation to the top layer and do let your worms safely back out into the garden once you have finished the experiment!

References:
Morgan, T. H., 1901. Regeneration. MacMillan, New York.
Chris Maynard, 2001. Backyard Science. Dorling Kindersley, US.

Further reading:

Earthworm facts and photos

Thought of the day – "What’s in a hug?"

Thought of the day – "What’s in a hug?"

nao

What is in a hug?  More than you might think!  We all know that a hug is a good way of expressing  love, affection, jubilation, happiness, sympathy, comfort or friendship; hugs can cheer us up and strengthen relationships but the science behind a hug can go a lot deeper!

Hugs all round for health and happiness!
Hugs all round for health and happiness!

 

We need 4 hugs a day for survival. We need 8 hugs a day for maintenance. We need 12 hugs a day for growth

—Virginia Satir, family therapist

 

The positive bonds of a relationship can be greatly increased just by the physical proximity and contact bet ween the two people hugging.  Studies have shown that couples that hug regularly are more inclined to stay together!

There are even reports that hugging yourself can reduce pain!

A good hug, as recommended, by social anthropologist Jean Smith,  should last for 20 seconds or more.   These hugs can increase oxytocin levels in our bodies making us happier and more relaxed.  Increased oxytocin levels result in a lowering of blood pressure and other stress related symptoms.  Oxytocin can also increase our social connections and is produced at many stages of bonding in life – such as at birth and during breast feeding.  So we become happier, more content, healthier and more relaxed, all in 20 seconds – now that’s another miracle of nature, don’t you think?

…..just a thought!

Thought of the day… "when is a weed not a weed?"

Thought of the day… "when is a weed not a weed?"

nao

Some people see them as the scourge of their flower bed, others as a natural and wild source of food and medicine but what exactly is a weed and are they really just a plant growing in the wrong place?

There is no biological definition for a weed, the Concise Oxford English Dictionary’s definition is a wild plant growing where it is not wanted and in competition with cultivated plants.  I like dabbling in the occasional harvesting of the wild for the purpose of food, drinks and even mild medicine.  Last week we gathered some young nettles and made a delicious pesto!  I have to admit I got a great kick out of gathering something growing wild in the garden and changing it into something tasty and nutritious!  Nettles can be used very much like spinach but contain higher levels of trace elements and minerals.  They are good for detoxifying and cleansing the blood as well as reducing many ailments associated with inflammation.

Homemade nettle pest
Homemade nettle pest

Just on my doorstep (well almost) is the Corrib Lake, the second largest lake in Ireland.  Unfortunately, certain parts of the lake are currently under invasion from a non-native species – the curly-leaved waterweed (Lagarosiphon major).  This weed has become a real problem within the lake and has a negative impact on the population of brown trout for which the lake is renowned.I can’t deny I grumble about weeding, but overall I like plants that have a function other than just aesthetic pleasure and to me weeds often fall into this category.  However, there is the flip side!  Just as within the animal world, it is often not a good idea to introduce non-native species to a new environment!

So which side of the fence do you sit on when it comes to defining weeds, or are you like me, jumping back and forward depending on the weed that’s in it?

…. just a thought!

Yeti Crab

Yeti Crab

nao

Week 8th – 14th April

Did you manage to guess last weeks CAN YOU NAME THIS CREATURE? …. I got two correct answers… from Dave at The Wedding Artist and from Michael at Nature Learn; Well done because it was a tricky one I thought.

So what was it?  It was a YETI CRAB (Kiwa hirsuta)… a deep sea crustacean newly discovered in 2005.

photo credit: ditzywolflady via photopin cc
photo credit: ditzywolflady via photopin cc
These wonderful looking creatures are deep sea dwellers.  The are found on the ocean floor off Easter Island.  It is thought that the “fur” on their legs might actually trap bacteria given off by hydrothermal vents.
In 2006 another species of yeti crab (Kiwa puravide) was discovered off the coast of Costa Rica, living in deep methane filed fissures.
Bacteria were also found on the silky hairs of the Kiwa purivida and it is thought that the crab literally farms the bacteria on the hairs of it legs, feeding them, maintaining them and ultimately harvesting and eating them.  It is likely that bacteria on the Kiwa hirsuta arrive at a similar fate!
Farming food on their own bodies…another marvel of nature!
Thought of the day…"A bee in my bonnet!"

Thought of the day…"A bee in my bonnet!"

nao

We found this little visitor in our house the other day… a nice big Bumble Bee… all Apiphobics look away now!

I think the poor guy woke a bit too early and was taking refuge in the warmth of our house!

There are about 20 different species of Bumble Bees in Ireland.  Although they do not build the large hives like their relatives, the honey bee, they do still live in colonies (usually with about 50 bees per colony) and are important pollinators of crops and cultivated and wild plants.  Due to the increased use of pesticides within gardens and agriculture, bee populations are declining at an alarming rate.  This is leading to a call in some countries for legislation to ban certain pesticides know to be detrimental to bee populations.

We can also make small changes within our own gardens: as well as the obvious switch to organic gardening we can choose to grow bee friendly plants and even prepare simple structures to encourage bees to come live in our gardens!

A great eco-friendly project to get your children involved with, don’t you think?

……just a thought!

Thought for the day – imagination!

Thought for the day – imagination!

nao

This is one of my favourite quotes …

“I am enough of an artist to draw freely upon my imagination. Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world.”

― Albert Einstein

 

….it always makes me think of my daughter, she has the most amazing imagination I have ever come across; when she was very young she told me I was not her real mum and one day she would have to leave me and go back to her real family!  Apparently she is a fairy princess and when the wicked witch attacked their kingdom her parents changed her into a baby in my tummy to keep her safe!

photo credit: crowolf via photopin cc
photo credit: crowolf via photopin cc

I see her imagination as a wonderful gift and feel humbled and nervous about the responsibility of keeping it nurtured and alive while she grows!

…just a thought!

"Thought of the day"….Why do hens lay unfertilized eggs?

"Thought of the day"….Why do hens lay unfertilized eggs?

nao
Following on from this weeks blog about all things eggy – today’s thought is …”Why DO hens lay unfertilized eggs?”
It seems like quite a wasteful process, don’t you think?  All that protein, fat, nutrients, calcium that go into the making of one hen’s egg – what is the point in going to all that trouble if there will be no offspring at the end of it?
Here are a few of my thoughts on the matter…
  • Firstly, we are looking at the fairly recent domestication of the species; in the wild it is likely that roosters would be naturally part of the flock and all eggs produced would be fertilized.  In the domestic situation roosters are often not present but the evolution of the hen has not (as yet anyway) been modified!
  • If we look at egg production in any species we will notice that eggs are usually released and developed in a cyclic manner (we humans are no different).  If you see this cyclic process as being wasteful at times then the label will fit for most animals, not just the humble hen!
photo credit: martinteschner via photopin cc
photo credit: martinteschner via photopin cc
  • Finally, you could suggest that it is a downside to the evolution of the egg shell!  Animals that produce soft shelled eggs usually have a requirement for water in the reproductive process.  In fact, for many of these species the eggs are fertilized outside the female body.  Although the addition of an egg shell removed the dependence on water for reproduction, it also removed the possibility of fertilisation once the egg is laid!

So there you have it, these are some of my thoughts on the subject.  I am not suggesting that any of these points are backed up with scientific findings…. the are just the random thoughts of this simple scientist! Maybe you have your own theories to add?

…just a thought!
"Mammy I hatched an egg!"

"Mammy I hatched an egg!"

nao

As a mother of three young children I have had many charming moments that I feel I will remember forever…. first steps, first words, how they pronounced a certain word, the list is endless.  Memories to cherish for a lifetime…. and then I forget!! Startling but true!  More moments forgotten than remembered.  However, certain things will stay with me forever…. like when my daughter was five and we got chickens for the first time; she was beginning to learn the joy of finding and collecting the eggs each day.  One day she came to the back door with her bounty only to trip at the step and drop an egg.  The poor thing burst into tears with the dramatic exclamation…

……………………………….”MAMMY, I HATCHED AN EGG!

Image credit: Graham Ettridge

I will never forget that one!  It was hard to keep a straight face as I tried to console my sobbing child.  With all the egg activities and treats of the Easter it has certainly got us talking and thinking about eggs in this house, have you ever wondered about these marvels of nature?

WHAT IS AN EGG MADE OF?

Firstly, what exactly is an egg made of and what purpose does each component have?

Image source: http://www.exploratorium.edu

The shell:  the egg shell is made of calcium carbonate (95%), just like the enamel of our teeth (see previous post).  The other 5% of the egg shell is made up of calcium phosphate, magnesium carbonate and proteins. Although the shell gives the egg it’s strength you might be surprised to learn that it actually contains up to 7,000 tiny holes (pores);  these pores allow air and moisture pass through the shell.

The bloom/cuticle:  this is a protein coating outside the egg shell that acts as a natural barrier to bacteria and dust while reducing moisture loss.

The membrane:  there are two layers of membrane just inside the shell called the outer and inner membrane.  These membranes are like layers of skin and contain a protein called keratin, which is found in our own nails and hair!

The yoke: the yellow of the egg contained within a membrane called the vitelline membrane.  The yolk is the part of the egg that feeds the developing embryo – it has a very high protein content and is also rich in vitamins and minerals.  The yolk contains all of the egg’s fat and cholesterol.  The yolk is the primary food store for the developing chick.

The Albumen: this is the white of the egg; it has a high protein and water content. The albumen cushions the developing chick and keeps it moist while still in the egg.

The air cell: this is a pocket of air at the wide end of the egg, created between the outer and inner membrane.  The air cell gets bigger as the egg ages.

The chalazea:  these are spiral ropes of egg white that keep the yolk in place.

WHAT ANIMALS LAY EGGS?

Animals that lay eggs are called oviparous and they include birds, fish, amphibians, many reptiles, many arachnids and insects, some molluscs and two mammals – the echidna and the platypus.  Mammals that lay eggs are referred to as momtremes.

A BIT OF EGG EVOLUTION

The reptile is credited as inventing the egg shell, allowing their young to develop outside the mother’s body.  All true dinosaurs are reptiles and they all laid eggs.  The development of the egg shell has been a fundamental step in evolution as it allowed the embryo develop in self contained egg, without the requirement for water.  This removed animals’ dependence on water for breeding.

HOW IS AN EGG MADE?

In the hen it takes about 24 to 26 hours to produce an egg.  An egg is made from the inside out, starting with the yolk which is released from the hens ovary and moves through various parts of the body where another element of the egg is added until finally the finished egg reaches the vent and the egg is laid.  Within 30 minutes of laying an egg, the process will start for the hen all over again.

SO WHAT GOES ON INSIDE THE EGG?

The embryo has started to develop in the egg while it is still being made within the body of the hen.  Once the egg is laid the development of the embryo will only continue if conditions are correct.  If the temperature and humidity levels are right (temp approx 22oC, relative humidity 50% ) the development of the embryo will continue after the egg is laid.  This process continues for approximately 21 days.  If the egg is being hatched under a broody hen then the hen must turn the eggs regularly.

THE HATCHING PROCESS

Image credit: http://www.waldeneffect.org

Finally, when the time is right, its time to crack out and see the world.  The young of many egg-laying species are equipped with an egg tooth – a tooth like projection on the end of a beak (birds) or protruding from a jaw (reptiles) that helps the young animal tear through the membrane and break through the hard shell.  The egg tooth will eventually be reabsorbed or fall off.

Chicks and many other animals will hatch from the larger, rounded side of the egg.  That is because this is the end where the air cell is usually located.  Once the chick becomes too larger to receive enough oxygen from inside the egg it will use it’s egg tooth to pierce through the inner membrane into the air cell space.  This provides them with an extra supply of oxygen, just enough to sustain them as they continue the hatching process and crack and break though the egg shell.

We have been lucky enough to hatch a few broods of chicks over the years and it is always so exciting to meet the little ones for the first time.

This is chips – one of our brood!

So the only other question to be addressed is “which came first – the chicken or the egg?” but I think that’s a blog in itself, perhaps for another day!

AN EXPERIMENT TO TRY – HOW STRONG IS AN EGGSHELL?

You would be amazed how strong an egg shell is, although you might want to try this one over a sink!
Hold a raw egg between your thumb and first finger, holding at the two ends and then apply pressure – as hard as you can!  You might be surprised to notice that the egg doesn’t break!

If you repeat this but apply the pressure to the sides of the egg, things might not go so well and you might find yourself covered in egg!

So why is this?  Although an egg shell can be very fragile, it’s shape can provide it with great strength.  This is because the egg is dome shaped at the top and the bottom, just like a bridge structure;  this structure means that when you apply pressure the force is distributed evenly over the shell, not just on one point, hence the egg does not crack!

Further reading:
Anatomy of an egg
Eggshell
Poultry reproduction and incubation

 

The Thorn bug

The Thorn bug

nao

Week 1st – 7th April 2013

Did you guess this weeks CAN YOU NAME THIS CREATURE?

I got some correct responses…. it was a thorn bug ( a treehopper).  These bugs can be found on all continents except Antartica.  As you can see from the photo, they are excellent mimics of thorns on the plants and trees on which they feed.

photo credit: mmmavocado via photopin cc
photo credit: mmmavocado via photopin cc

These thorn-like protrusions on their backs act as a wonderful camouflage to prevent detection by predators.  They also act as protective armour if attacked.  These insects cut into the stem of the plant and feed on its sap.  The females of most species cut into the bark to lay their eggs and often sit on their eggs to protect them.  In some species there is even collaborative egg minding between females!

Another of nature’s wonderful creations!

Lacewing Larva

Lacewing Larva

nao

Week 25th – 31st March

Last weeks “can you name this creature?” image was supplied by Molly, who is ten years old.  Molly spotted this in her garden and, with the help of her Dad, Michael at Nature Learn, has shared it with me for this slot.  A big thanks to Molly!!

Lacewing larva – photo credit Michael and Molly Bell

So did anyone guess what creature this is?

It is a LACEWING LARVA!  A hard one this week I know, but we did give you some good clues!
I thought Molly did particularly well to spot this little guy as they only grow to between four to seven mm in length!

So now you know what it is do you want to learn some more?

These lacewing larva are a welcome addition to any garden as they like to dine on soft bodied insects, particularly aphids!  They like to hang out in humid environments and can be a great gardening aid to any greenhouse or poly tunnel!  They also feast on the eggs of certain other insects and spiders, as well as mites and mealy bugs.  All in all a real asset to the garden!

Although the larva stage does not last more than two to three weeks these little guys certainly have a big appetite …. consuming up to 600 aphids during this period.  The larva must make direct contact with it’s prey… injecting digestive enzymes into it and sucking back up the digested body parts once the enzymes have done their work!

Lacewing larvae are also experts in the art of camouflage, they often cover their bodies in debris to hide them from predators.  This debris often includes bits of body parts from their own prey!