Greetings from Planet Science! Another week under our belt and the holidays have completely faded away. Or washed away more like. How much rain? Anyway, looks like this is an exciting time for science with the LHC and all. Watch this space...

The line-up this week:

1. Gimme Five – ways to celebrate Organic Fortnight
2. Stump the Scientist – do fish sleep?
3. Activity of the Week – Ketchup Sachet
4. Creature Feature – The Walking Catfish
5. Mouses at the Ready – Molymod A’ level Chemistry kit
6. Noticeboard – FYI
7. Recommended websites of the week
8. The Winners’ Enclosure
9. Joke of the Week

Bears

1. The Spectacled Bear is named for the cream-coloured circular bands which ring its eyes.
2. The Giant Panda has six digits on its front paws, giving it an opposable thumb ideal for holding onto the stalks of bamboo.
3. The hairs of a Polar Bear pelt appear to be white, but are actually translucent and transmit the light down to the skin.
4. The brown bear distinguishes itself from the other ursines by virtue of its shoulder hump, which is caused by muscles which are used for digging.
5. The Koala is not a bear but like its Australian counterpart, the Kangaroo, is in fact a marsupial.

This week’s stumper comes from Anne Brown of Swanage Middle School who asks

“Why are there no green mammals? Many mammals live in habitats where the predominant colour is green, many would benefit from camouflage in that habitat. So why, after years of evolution, has there not occurred a single green mammal (as far as I can recall)?”

Why indeedy? Over to you, scientists...

If you can help or have a burning question of your own then send us an email with STUMP THE SCIENTIST in the subject line to planet-science.news@nesta.org.uk

Oh the old ones are always the best, they say. So let’s revisit this activity from way back in Science Year.

Ketchup Sachet

You will need:

• 2 litre plastic bottle
• A sachet of ketchup
• Sachets of other sauces to experiment with (optional)

What you do:

1. Fill the bottle full of water.
2. Put the sachet in the top and secure the lid on.
3. Let go and it’ll float back up.

What's going on?

An object will only sink if it is denser that the fluid around it, otherwise it floats. The ketchup is denser than water, so should sink. But your sachet of ketchup is actually ketchup plus packaging plus an air bubble, so overall it is less dense than ketchup on its own, and floats somewhere around the middle of your bottle.

Press the sides of the bottle and you’ll make the volume of the bottle smaller. Everything inside the bottle is compressed (squashed). Gases compress easily compared to liquids, so it is the air bubble inside your sachet that gets squashed the most. Now the air bubble is denser, so your ‘ketchup + packaging + an air bubble’ is also denser than before, therefore it isn’t as buoyant (floatable), and sinks.

More ideas

If the experiment doesn't work for your sachet of ketchup, maybe you've found one that is filled very efficiently and there isn't very much air in it.

You could try getting sachets from different places.

Or you could try a more old fashioned but fiddly way using a pen lid and some blu-tack or modelling clay. Use the blu-tack to seal the pen lid so that water can't get in. As there is air inside your pen lid it should act like the air bubble in the ketchup, but you will probably need several goes before you work out how much blu-tack to use. If you have too much, the lid just sinks anyway. If you have too little, the lid just floats even when you squeeze the bottle.

This activity came from the Little Book of Experiments

Walking Catfish

There are some very odd animal names around and none more so within the world of fish where we discover such creatures as the Sarcastic Fringehead . Now there’s a name to conjure with. Alas that’s all you can really say for it, as it has no other particularly amazing features. Which just goes to prove the marketing gurus – it’s all in the name.

Anyhow whilst trawling through the fishy waters we came across another critter – the Walking Catfish. Now we’re intrigued...

The Walking Catfish, Clarias batrachus, is a species of freshwater, airbreathing catfish found primarily in Southeast Asia, so named for its ability to ‘walk’ across dry land, to find food or suitable environments. When we say ‘walk’ we don’t mean it actually strolls about as we humans do but it uses its pectoral fins to keep itself upright and makes a wriggling motion with snakelike movements. It can survive using this form of locomotion as long as it stays moist

However a certain collective species of walking catfish found primarily in the vicinity of the Panama islands and southern America are large enough that they use their long whiskers as tentacle-like mechanisms. They will use these “tentacles” to prey on smaller marine animals and even use them to aid ‘walking’. It has been suggested that these catfish use their tentacle-like whiskers to pry open wires protecting private bodies of water to enter and prey on unsuspecting fish. Oooh the little devils! Trespassing and then legging it to avoid getting caught.

Find out more details about the Walking Catfish

Let’s hope it never becomes a serious contender for cod or haddock. Oy mate! Me fish has walked off with me chips!

Boy o boy do we have a giveaway for you this week...

Only a Molymod Molecular Model set for A’ level Chemistry! Hours of fun for the budding molecular modeller. K’nex? Who needs it? Lego? It laughs in the face of Lego. Molymod sets consist of a variety of atom parts and links designed to make a large number of possible structures relevant to a specific chemistry subject. So thanks to Molymod for giving us this fantastic set.

Would you like to win it? If so, then email us with your name and address, and the words ‘A MODEL CHEMIST’ in the subject line, to:
planet-science.news@nesta.org.uk.
The draw will take place at 5pm on Wednesday 17 September.

This week we’ve been having a look at Anatomy Arcade which is strangely addictive. We’re particularly fond of Whack-a Bone . If only we could get past Level Two and actually get whacking! What a brilliant way to learn about the skeleton. Brace yourself if you’re about to have a go at Treat It or Eat It though. Some of the images are pretty gruesome. Just as you anticipate some ghastly infected wound, you discover it’s actually a slice of strawberry cheesecake! And vice versa. Very clever.

By the way, if you’ve got a good website to recommend then send it along to us at planet-science.news@nesta.org.uk with RWW in the subject line. Thank you very gladly.