It has come to my attention that some people think I can grow plants. In reality, I have a black thumb. I can germinate them, but then they always die, or go mouldy, or are blown away in a cyclone (seriously!) or are otherwise stunted and sickly.

So here I am very proudly showing off the first time ever I have had plants live long enough to produce flowers and baby tomatoes. I’ll be stoked if we get to eat any of them, but I’m not counting any chickens until they are bright red and in the salad. The girls are eating the basil leaves up the top already – they think they are being very sneaky. Which is hilarious, because in food they flatly refuse to go near herbs.

I think the secret to my success this time is that these plants seem to be bomb-proof. This one had a water bottle dropped on it and snap it off completely, and now it’s sprouting new leaves!

Usually I can’t keep them alive at any price, now I have zombie plants.

We had another couple of days without internet which is why there was no quiz posted on Tuesday. Even the trusty 3G failed so no mobile devices either. It gave me an excuse for a trawl on YouTube to find some fun and interesting videos to share instead. An easy way to finish the week.

More maths than science but this is one of the big girl’s favourites – From They Might Be Giants, Triops Has Three Eyes.

Another TMBG, I like that this one can be done as a round. And as someone who struggles every week to make things simple but keep their accuracy, this is a pretty darn good explanation of shooting stars.

Enjoyable but esoteric, I’m impressed that someone put the time in for this. Taking a set of nonsensical letters and somehow making them fit a rhythm and melody then pronouncing them must have been a challenge. It’s actually the symbols of the periodic table of elements in order.

I love any excuse for pulling out the Symphony of Science.  These are amazingly well done, pulling out significant quotes that fit and the video adds to it. It’s not something I’m good at myself, but I love seeing different and artistic ways of exploring complex things.

1.     Amphibians are the only group of animals with legs like us (bones, organs etc – the tetrapods) that are not adapted to have young on dry land. Although this breaks down a little because there are some who have live young, such as stomach-brooding frogs or some caecilians. It’s nice and simple for us to think of eggs or frogs as ‘primitive’ and live births as ‘advanced,’ but the world doesn’t obligingly do what we want. Even some of the egg layers provide parental care, moving their tadpoles and laying unfertilised eggs for them to feed on.

There are three types of amphibians, frogs and toads, newts and salamanders (which look like lizards), and caecilians. I’d never heard of caecilians before, but they are completely legless and look like worms or slippery snakes. Some of the features of amphibians are:

• They go through a larval stage with gills (although this might be inside a parent).
• Their eggs have a simple membrane and need to be in water or wet soil.
• Their skin doesn’t have scales or keratin to protect it, so it needs to stay moist. They can breathe through it, although they generally have lungs as well.
• They cannot maintain their body temperature above their surroundings, so their activity depends on high temperatures. The advantage is that they need less food because they don’t have to generate their own heat.
• Adults are carnivores.

2.     The thin skin is great to allow them to hibernate at the bottom of ponds, but it doesn’t give them protection from predators in the way scales or fur does. So all amphibians have developed toxins of some sort. This does not mean they are all poisonous to humans, but are aimed at their main predators. Some, such as the Golden Poison Frog are highly poisonous to humans.

Photo courtesy of H. Crisp

Many of the poisonous amphibians are brightly coloured to warn off predators, the same way butterflies and caterpillars are. Have a look at the video for some interesting colours.

Cane toads are the most commonly known poison amphibian in Australia. The eggs and tadpoles are extemely toxic, but young toadlets are not. It isn’t until they are mature that they start to produce their own toxin. Some crows have discovered that the belly skin does not have poison glands, and have been known to flip the toads over and eat them from the belly side.

3.     Newts are the only vertebrates capable of regenerating complex structures such as limbs. We have very limited regeneration ability, only being able to heal things like skin, the liver and some bones. Interestingly, children do appear to be able to regrow fingertips, and there have been isolated cases in adults as well.

4.     Modern amphibians tend to be small, with the largest up to around 50cm for toads with stretched legs. But in the past some were much bigger, even several metres long. There is nothing inherently ‘works better when small’ about amphibians, although certain shapes are needed for large, cold-blooded animals. During the Carboniferous they were the top land predators and filled the same niches as crocodiles today, with roughly the same size and shape. But during the Triassic reptiles and mammals evolved.

These two aren’t tied to the water in the same way as amphibians are, who need it for their young. Mammals and reptiles have eggs that take the water with them or hold it inside themselves and thick skin, which allowed them to move away from rivers and lakes. With so many more places to live, reptiles took over many of the larger niches and pushed amphibians into the smaller ecological zones.

5.     Up the top is an axolotl, or Mexican Walking Fish. They are a type of salamander that stays in the water their whole life, becoming sexually mature while they still looking and living like larvae. The frills behind its head are its gills, which are usually lost in adult amphibians. It’s a bit like a caterpillar that doesn’t bother turning into a butterfly. With great difficulty some can be forced to ‘grow up,’ but most die and the ones who change die far, far more quickly.

Staying like a juvenile while being sexually mature is quite common and is called neoteny (nee-O-tenee). It demonstrates that a small tweak in a genetic or developmental pathway can cause very large changes in the final adults, as you can see when you compare the Axolotl to the closely related Tiger Salamander adult.

Tiger Salamander by Carla Isabel Ribeiro

A neotenous animal we all know well are humans. So many of our features, from bones in our feet, to relative hairlessness, to teeth, to rapid brain growth are like juvenile apes rather than adults. I’m certainly not saying we’re just baby apes, but a general stretching of development and staying more like a juvenile has been very important in human evolution.

Brightly coloured poisonous frogs, rather than hiding they warn predators off.

Hands are one of the things that have made humans so successful, you could call them fundamental to what we are. But they aren’t unique or specialised. In fact it’s pretty much the opposite – every primate and lots of other little brown animals have hands. Horses’ hooves are specialised. We have been successful by staying primitive and generalised and keeping our options open. Even if horses suddenly became super intelligent, they’re not going to be making tools.

This is not to say that hands aren’t special. You could argue that they have had so many millions of years to perfect themselves to give us the range of grips, movements and power or delicacy we have.

Grasp

Babies and children develop different types of grasp or grip as they get control over the muscles in the hands.

Palmar grasp

This is a primitive reflex babies are born with. When anything lightly strokes their palm, including clothes, hands or fingers, their fingers curl in and they grip it strongly. This obviously had its origin in primate babies holding on to their mothers, and it has survived because it could still be valuable for a carried baby to be able to grab on. It is strong enough to support them, but don’t count on it because they can let go suddenly.

Power grasp

Babies begin to be able to purposely grip at around 4 months using a power grasp. They swipe at objects as they begin to control the arms and hands and sometimes manage to grab on. In a power grasp the object is held against the palm with the fingers and thumb wrapped around opposite sides.  This is when things like balls, egg rattles and bells are popular, or large soft toys they can hold and scrunch.

It may look simple but it is still a very complicated movement. The hand needs to open first, then the joints of the fingers need to bend in the right order from the base to the tips to wrap around the object. In a tight grip the wrist bends backwards as well.

Precision grasp

The precision or pincer grasp uses the tips of the fingers and thumb rather than bringing the object in to the palm. This takes a long time to develop because it requires fine control over all the little muscles of the hands and fingers. The beginning of the precision grip is a four-finger grip, using all the fingers but not the palm. Babies don’t start using this grip until they are almost one. Games to play with it are anything where they can pick up smaller objects, including finger feeding or blocks. A box they can fill and empty is very popular.

From the four finger grip they develop the pincer grasp with just the index or first two fingers. This is usually takes several years to develop, and school children still need help with it for things like scissors and pencils. Threading onto pipecleaners or straws then ribbons is good practice, as well as imaginative play with small animals or characters to move around.

Games

There are so many games out there you can do to help children gain control of their hands and fingers that can be used at lots of different ages.

• Rhymes – from ‘Round and Round the Garden’ through ‘Once I Caught a Fish Alive’ to ‘Incey Wincey Spider’
• Pointing games.
• Holding, throwing/tapping and catching with beanbags or soft balls.
• Stacking and building.
• Posting.
• Cutting, gluing and writing.
• Tracing around hands then using them to make flowers or leaves.
• Hand prints and glue
• Party tricks
• Threading.

Fingerprints

And for the older kids, fingerprinting is lots of fun. Over the years I’ve found the simplest way to get fingerprints is using a large nibbed texta. Whiteboard markers or permanent markers can work if you are quick, but kids’ textas like crayola are the best. Likewise school textas with small points can work, but they tend to be a lot dryer.

All you have to do is quickly colour the fingertip then push onto a page, either rolling the finger to get the whole thing or just pushing down to get an oval. It’s not the clearest of impressions, but it’s much easier and more independent than trying to use ink or paint and it can be seen.

Then you can look closely and identify your own personal fingerprint pattern. It’s interesting if you have boys and girls to compare, because there are some differences.

Mine is left thumb – L, W, L, W, L,  right thumb – W, W, L, W, L.

Or do other things with them.

Kermit said it’s not easy being green, but how much do you know about him?

1. What are amphibians?
2. Are they poisonous?
3. Why are amphibians medically interesting?
4. How big do they get?
5. And what’s up the top? Photo by LoKiLeCh

Answers here, with video of multi-coloured frogs.

1.     The word ‘electric’ comes from the Greek elektron, amber. Rubbing amber with wool or fur produces static electricity and the amber attracts small pieces of ash or paper. The Greeks thought it was a form of magnetism in non-metals. It wasn’t until 1600 that it was recognised as different.

2.     Lightning is a giant spark of static electricity, although the details on how it works are still unknown. All atoms have a positive nucleus in the centre and negative electrons around the outside. In some situations, like rubbing amber, some electrons can be stripped off and temporarily attached to other atoms. This gives you an unbalanced charge when the materials are separated, with one positive and the other negative. They need to touch something else for more electrons to move and the charges balance. Sometimes the electrons will jump a gap and we see them as a spark. How far they can jump depends on how strong the charge difference is.

In lightning a difference in charge builds up in a cloud or between a cloud and the ground. It is unknown how it is triggered, but the imbalance is strong enough that the spark, or lightning, can make the enormous leap.

3.     Transformers have shaped the way we generate and use electricity, the way power grids work and our safety with electric devices. Transformers rely on something called induction. I’ve mentioned before about the link between movement, magnets and electric current. In a transformer you put current through an electric coil, producing a magnetic field. Then you have another coil next to it and the magnetic field will produce a current in that coil. The trick is that you can wind the coils more or less to change the voltage in the second coil.

Transformers are used to step voltage up or down. For efficient long distance transmission of power it needs to be high voltage and low current, so massive transformers have literally created our energy grids. They allow a single power station to send electricity to distant locations. Without transformers we would need many small, close power stations.

There are also transformers in all electrical equipment. They step the high voltage of mains power down to the voltage that the circuits of the appliance can handle, and isolate us from the more dangerous mains power.

4.     We have electricity in our bodies because of how salts dissolve. We know that table salt is sodium chloride, NaCl, and can use that as an example. When NaCl dissolves it splits into positive Na+ and negative Cl- ions. Cells have sophisticated ways of controlling how much of different ions are inside, and resting cells are all slightly negative because they have more negative ions than the surrounding fluid.

When a nerve cell is stimulated it will open or close gates to allow different amounts of sodium and potassium to move across the cell membrane and change the charge. Nerve cells are like wiring in your body – they have very long arms that communicate between your extremities and your brain. And just like a wire, when there is an electrical change in one end it spreads along the cell, taking the signal with it. This is how nerve signals travel so quickly through your body.

This is the reason it’s so important to maintain the right balance of things like sodium and potassium in your body. Sweating and diarrhoea don’t just take water out, they also take electrolytes out and that’s why children who are sick are given a replacement drink rather than plain water. It’s also the mechanism behind water intoxication, where people drink so much plain water they upset the balance of electrolytes in their brain.

A special use of electricity in your body is the sinoatrial node, the pacemaker for your heart. It was proven that hearts do not rely on the brain to beat when a frog heart was isolated in a jar of electrolytic solution and beat on its own. The SA node sends waves of electrical activity around the heart, causing the muscle cells to contract. When people are fitted with a pacemaker this is what is being replaced.

5.     The critter up the top is a platypus, and along with echidnas they are the only mammals to use electricity for electrolocation. They hunt for small crustaceans in the mud of river bottoms, closing their eyes, ears and nose when they dive. The electroreceptors are in their bill, which they sweep from side to side in the mud. Their prey produce tiny electrical currents from muscle contractions when they move, just like electrical currents are produced in our own bodies. This helps the platypus tell them apart from rocks and mud.

You can see it in this movie, and look how enormous those flippers are!

Electricity isn’t just that thing that makes your computer and lights work. It’s all around and inside us as well.

1. Where did the word ‘electric’ come from?
2. How do lightning bolts work?
3. Why do we need transformers?
4. How does your body use electricity?
5. How do the critters up the top use electricity?

Answers here.

In fact so do a lot of other animals, this walking on ‘feet’ business isn’t as simple as it seems. If you have a look at this photo something looks distinctly wrong about that bend in the middle. (Photo by Frank Vincentz)

Photo by Charles J Sharp

And this one, that looks right for a finch, but isn’t it wrong for a knee?

Photo by Norrin Strange

If this is the view of a bird leg you’re used to, by now you’re probably confused. Thigh up the top, then the drumstick is really the calf and that knee certainly looks like it’s going the right way.

What is going on? Do their knees go backwards or forwards?

Relax, it’s fine. Really what’s happening is that feathers hide a multitude of sins, or in this case body parts. We are mixing up the bits we see on the roast and the bits we see on the live bird (at least I assume other people have this mental blink, I certainly do).

Photo by Tórizs István

If you look at these chicken legs here complete with impressive spur, you’ll quickly realise that they aren’t the drumstick. The drumstick is the feathery bit up the top, the thigh is completely hidden. These are actually the chicken feet. It doesn’t help that you get birds named things like ‘red legged kittiwake’ or ‘yellow legged gull’ – anything that doesn’t have feathers on it is a foot, and the toes down the bottom are just the toes.

This skeleton makes it clear, especially if you look at the back leg. Up the top is the short, chunky thigh, completely hidden under the feathers along with the knee. Then comes the long slender calf, which would make your emu drumstick. The joint in the middle that we think of as a knee is actually the ankle, which is why it bends that way. Down the bottom are just the toes.

And for the visual, here’s a cassowary ‘standing’ on its ‘feet.’

Photo courtesy of Dezidor

Can you imagine trying to walk like that? Once again, we are tricked by our assumption that the rest of the world is just like us. In reality, birds walk on their toes.

What do you know about the things your little one is playing with? Close your eyes and click for the questions.

1.     In spite of all the lovely pastel things in shops and our desire to smother our delicate little newborns in pale colours, they can’t really see them properly. They see contrast and movement, so black and white and then bright red and green are the best. Babies are also very attracted to eyes, even extremely young babies can tell where a simple face made of shapes is looking and will follow its gaze. Which might not be such a good idea in a mobile.

A really simple mobile is to use a needle to thread across a lot of straws so they can spin. Pipecleaners are brighter, but unfortunately they have sharp metal ends. Simple cardboard discs with black and white patterns can also be glued to string or sewn together.

2.     A spinning top is actually a simple gyroscope. When you spin it, it has something called angular momentum, which is the equivalent of normal linear momentum – it takes a force to change the speed or direction something is moving in. For a top, it would need a force to change the axis it’s spinning around. So unless something pushes it, it will continue to spin upright.

Except something does push on it – gravity. If the spin axis isn’t perfectly vertical and the weight balanced, gravity will begin to overbalance it and the axis moves around like a cone. This is called precession. As the top slows the wobbling gets more and more exaggerated until it rolls to a stop.

Courtesy of Philippe Teuwen

3.     Ancient toys are extremely similar to modern toys, without the electronic bells and whistles. There are lots of rattles and dice, plus dolls and little horses on wheels – the equivalent of toy cars?

A toy from Mohenjo-daro, an ancient Indian civilisation.

4.     Personally I can’t get a car to loop but I have done it with a marble.  It’s one of those things that are theoretically possible, but is anyone crazy enough to do it. I don’t think anyone’s done the forward loop, but Jeremy Clarkson of Top Gear appears to have done a barrel roll or corkscrew type loop around a tunnel. Video as normal at the end, you can join in the debate on whether it’s real. My take – I think there are different bits of footage spliced together. One is just a car going through a tunnel with lights etc. and Clarkson talking. The other is with the lights removed and a lot more safety gear happening, and probably a lot of takes! But that’s my completely uneducated opinion – I’m a biologist.

5.     The toy at the top is something of an illusion. To us, he looks like he is balancing precariously. In reality, he’s hanging from the wire, something we know is simple. The trick is that most of the weight, and therefore the centre of gravity, is hanging down below the wire on the ends of the balancing stick. Then it’s just a matter of making sure each side is even and he will stand there happily.

There are some very simple instructions and pictures to make your own here. I’ve done it a similar way, but using thin wire or pipe cleaner to make the balancing stick then plasticine on the ends.