Sunday 13 March 2011

Snail reproduction and mollusc birth control

One of my hobbies is snail-rearing. I started this when living in Dublin. In spring/summer 2007 it was so amazingly rainy (even for Irish people!) that thousands of snails could be seen in the gardens. It must have been really good news for birds.

I started to be interested in these animals, as I did not see many of them in dry, hot and full-of-concrete Madrid. When I left Ireland I brought three garden snails with me. And I continued my "collection" rearing snails from other countries such as Portugal, Andorra or Spain.

I saw them mating many times, but they appeared to be sterile, as they did not seem to be laying any eggs at all. Then I informed myself a bit, and I read that apparently this was because I was not putting any earth in the snail's box.

So I decided to make an experiment. There you go!

The idea: it is quite simple, the hypothesis to prove is

When earth is available, two snails will lay many fertile eggs after mating.

The material: a glass jar, two snails (apparently it does not matter the sex, as they are hermaphrodite) and some earth from the park down the street.

The method: The reason I used a jar was that in that moment I had seven snails in my snail box, and I did not want to have everyone's offspring, so I just chose two garden snails (one Irish and one Spanish, which happened to be called Yogurín and Tullido). The jar was small enough to keep them near to each other. To ensure ventilation I made small holes in the lid.

I left them in the "love jar" on 16th November 2009...

The measures: well, what can we mesure here? There are a few interesting things to measure, such as the amount of eggs, their viability and the time it took the little ones to hatch.

Happily, in less than 24 hours (!), on 17th November, at 1:20 AM, one of the lovers started laying eggs, here is the photo of that moment:

You can see about five eggs, and the head of the snail almost an inch into the earth. After some hours, the job was finished (next photo was taken at 9:55 PM). About sixty eggs buried and hidden from possible predators!

You can see them a bit better here:

Just in case you want to compare sizes, here they are next to a 50 euro cent coin:

As you can see, the egg cluster looks as big as the parent, it is incredible the fact that he/she was able to leave so many!

For logical reasons, I only kept four eggs. The other eggs were responsibly buried (and probably baby snails were born soon afterwards) in the very same spot where the Spanish parent was found, near the Alberche river, so no harm had been made to them, or to the environment (as there are already many similar snails mating and laying eggs over there anyway).

Here are the eggs I kept:

For some days I looked at the jar to see if the newborn snails were there. The eggs always looked exactly the same. Surprisingly, after eighteen days, on 5th December, they were there!

No shells appeared to be around (later I learned the first thing they eat is their own shell to get calcium). And the change was quite fast. A couple of days earlier they looked like white, small pellets, and then, suddenly... snails! Tiny, translucent but complete snails. For unknown reasons, only three out of four eggs were viable. The other one looked a bit elongated. But it is a good ratio anyway.

Just in case you are interested in sizes, here you have them on a one cent euro coin:

And here they are, in one of their first walks:

Conclusion: snail breeding is not that difficult! However, it seems I was a bit lucky as well. After this experience I tried to do the same with a couple of grove snails I brought from Portugal, and unhappily after many days they did not seem to give any results.

Just in case you wonder what happened to the snail family, the parents (after completing their normal life cycle) died at the age of three. One of the children disappeared (probably fled home, *sigh*). But the two remaining Irish-Spanish little ones grew into adulthood and have a happy snailly life at home. The photo below has been taken an hour ago.

Sunday 20 February 2011

How to compare heat capacities in your grandmother's kitchen

Performing simple sicentific measurements (such as getting the heat capacity of a given material) having proper scientific equipment is an easy, probably boring task.

However, things get funnier when our means are limited. For example, what about calculating and comparing the heat capacity of organic tissue and inorganic matter using only things you would find in any kitchen, such as your grandmother's kitchen? This means you cannot use the infrared thermometer your phisicist friend use to have in the drawer. And yes, you are right, the average grandmother does not use a microwave. Not at least nowadays.

So, first of all, we have to set an hypothesis to prove or disprove (otherwise, no science can be done, and we would wander from one thing to another... which might be interesting as well, but would not be really scientific).

The idea: following a small poll among a few non-scientific friends, I have found out that most of them would use a 20 kg hot stone instead of 20 kg of equally hot ham to put under the bed in a cold night. In other words,

A piece of granite would absorb more heat than a piece of ham the same weight.

so, according to this theory, if you had to store heat, you should use stones instead of food (provided that eating the food is cheating). Let us see if this is right.

The material: tap water, a freezer, a cooker, a small pot, three potatoes (sorry, no ham in my fridge, but these will do the trick), stones from the garden, a kitchen scale, a spoon (as stirring rod) and the timer of the cell phone (yes, I agree that the average grandmother would not have a cell phone, not at least in the kitchen, but you can always use your heartbeat... that is what Galileo did, and it worked pretty well for what he wanted to know about pendulums).

samples with 100 g of potatoes and 100 g of pabbles

The method: not having anything that resembles a thermometer, we will have to use as reference easy and a priori known temperatures. These could be the temperature of freezing water (0 ºC), the human body temperature (about 36 ºC) or the temperature of boiling water (100 ºC if you do not live too high; I live at 770 m, but this would just change this temperature by about 3 ºC, a negligible error if we compare with the error from other measures). To reduce the huge error we are going to have, we will use the widest range available: from freezing water to boiling water.

So, we first need to have boiling water in the pot. Then, we will drop in the 100 g of garden stones, which we have had for about five minutes in freezing water at 0 ºC, and calculate how long does it take for the water to boil again. Note that in order to make sure that the stones are at about 0 ºC, they must be in liquid water, but partially frozen; if we simply leave the stones in the freezer, they could easily reach temperatures of abuot -20 ºC.

We have to be as well careful when considering the boiling point: liquid water contains gases (air) dissolved in it, however, the amount of air dissolved is reduced with rising temperature (this is why salmons swim upriver, as cold water contains more oxygen for their offspring – you had one point in the chemistry exam if you knew this!), and this is the reason why a pot or a glass with hot water use to have little bubbles in its inner surface: they are the air that the water cannot keep any more. But the appearance of these bubbles must not to be confused with the posterior boiling point.

Then, we do the same for 100 g of raw potatoes and calculate the time the same way.

The heat capacity in J/kg·K will be:

(heat capacity in J/Kg•K) = (absorbed energy in J) / [(mass of pebbles/potatoes in kg) * 100 K]

You will say hey! how do I calculate the absorbed energy?. Well, that is why we are timing, as this can be calculated this way:

(energy absorbed by pebbles/potato in J) = (energy consumed by cooker in J) = (power of cooker in W) * (time in s)

Yet another small problem: we have to calculate the power of our cooker. So, this is when we start the next step...

The measures:

Calculation of the power of the cooker

100 mL samples of water during cooling process

Provided that the heat capacity of water is 4184 J/kg·K, I first used an indetermined amount of boiling water (to make sure the pot was already at about 100 ºC), dropped in 100 mL = 100 g of thawing/freezing (but not frozen) water, and calculated how long did it take for the water to boil again. I did this several times to have an average value:

WATER from time (s)to time (s)diffs/kg
100 g186.9275.788.7887
100 g275.7354.779.1791
100 g354.7434.679.9799
100 g434.6517.182.5825
100 g517.1614.297.1971

From these data we see that the average s/kg is 855 and the standard deviation is 75 s/kg. This way we can safely say that the power of our cooker is (490 ± 40) W (taking into account the propagation of error).

Calculation of the heat capacity of the potatoes

almost frozen potatoes about to be boiled, here the cell phone is used as stopwatch (the time the potatoes have been on the hand is negligible)

Three samples were used: two of 100 g and a smaller one of 28 g. They were cut in small pieces to make sure that, when water was boiling around the potato, the whole potato was at about 100 ºC. A spoon was used as stirring rod to guarantee the homogeneity of temperatures within the pot. This way, the following data were obtained:

POTATOfrom time (s)to time (s)diffs/kg
100 g0.091.091.0910
100 g134.7214.379.6796
28 g222.9247.724.8885

as the almost frozen potatoes enter the pot, the water stops boiling until the cooker gives enough heat to restore the boiling point

This gives us an average value for of 864 s/kg and a standard deviation of 60 s/kg, from which follows the specific heat of potatoes: (4200 ± 600) J/kg•K.

Calculation of the heat capacity of stones

We proceeded the same way, with the limitation that stones had not been broken into small parts.

STONESfrom time (s)to time (s)diffs/kg
100 g (several pebbles)319.6362.342.7427
137 g (conglomerate)384.0459.175.1548

More data could have been calculated, but as accuracy was not essential for this experiment, these were enough to get the average 488 s/kg and the standard deviation 86 s/kg, from which follows that the heat capacity of the stones were (2400 ± 600) J/kg•K.

The results: the error in the experiment is high, which is a consequence of the poor equipment available and the fact that we just garnered a few data. However, it is enough to see that organic tissue has about twice as much heat capacity compared to inorganic material.

Conclusion: potatoes (and presumably most of organic "living" matter) has a heat capacity very similar to the water: compare (4200 ± 600) J/kg•K to the 4184 J/kg•K of water. This is not surprising as it is well known that water is the main component of living matter.

Let us compare the (2400 ± 600) J/kg•K we have calculated for stones to the heat capacites of other inorganic substances, such as
  • iron: 450 J/kg•K
  • graphite: 710 J/kg•K
  • silicon: 703 J/kg•K
  • beryllium: 1820 J/kg•K
  • granito: 800 J/kg•K
  • sodium chloride: 854 J/kg•K
  • magnesium: 1020 J/kg•K

We can see that we have probably overestimated the heat capacity of our pebbles. Collecting more data and using bigger stones would provide more accurate information.

However, it is apparent the fact that for the same weight of pebbles and potatoes, the latter take quite longer to raise their temperature 100 ºC, which means they are storing more energy.

So, now we can safely refute the original hypothesis: it is indeed false that a piece of granite would absorb more heat than a piece of ham the same weight. Amusingly, and according to my fast poll, this seems to be counterintuitive.

I would be happy to read your comments about why should some people paradoxically think a stone is better than a piece of ham to keep oneself warm!

Friday 26 March 2010

Airport game

Waiting for a flight can be really boring, especially when we have to be there two hours earlier. If you are at an international airport, there is a very simple game you can play using the scientific method for non-scientific related activities.

The scientific method is a powerful and simple algorithm to separate what works from what does not work. There is a series of steps, and if you follow them, you will be able to say you deduced something scientifically, which means you have been working towards "truth" (if it works, you will know it works; if it does not work, you will not lose your time in that direction). These steps are, basically:

1) observe
2) guess what is happening
3) deduce something (from what you think is happening)
4) check if it works

So, when you are at the departure gate of an airport you can play a game, trying to guess where is a certain flight going. The rules are:

a) Watching at the screen where the destination is displayed is strictly prohibited until the last step.
b) You have to observe the people who is waiting at a certain departure gate. You cannot speak to them, nor ask them anything. Just observe them from where you are. You can also listen to the language they speak and their accent if you are near enough. You can check which newspapers and books they are reading, what are they wearing, etc.
c) Guess what is happening. If you are in Dublin and you see a lot of Irish and Spanish people with children and T-shirts, the flight is probably going somewhere in the Spanish seashore (some of them coming back from holidays, some going on holidays). If you see Asian, Indian, African, American and English people with briefcases, probably the flight is going to a metropolis like New York or London.
d) Make a hypothesis: using the information you have, guess the city they are flying to.
e) Check your hypothesis: read the destination in the concerning screen. Were you right?

You can, for example, add three points if the city was right, and one point if the country was right. Then, you can compete with a friend to see who is best at this.

However, I found this game interesting even when playing alone. Confirming our hypothesis is always rewarding. And if you are wrong... it is so funny seeing the difference between reality and what we think!

Have a good trip!

Friday 28 August 2009

Baby bird communication (II)

This is Piolín:

(Piolín is pronounced [piɔˈli:n], and it is the Spanish name of Tweety)

My niece found Piolín in June, saving him (or her... I have here the same problem I had with Patxi) from certain death, as he fell from his nest on a very hot day (under the Sun it must have been around 40ºC), lying on one side of a road. You can see a small wound on his back, probably caused by the fall.

As I discovered later, after some research, and despite his aspect, Piolín was not an ET, but a baby sparrow. When we found him he was one to three days old. He could not be quite older than that, because he had not even opened his eyes yet.

We started feeding him with some water and wet bread, and, as this video shows, he was hungry:

I observed that Piolín, as every baby, used to sleep or rest a lot when there was no activity around. But when he felt my presence, he always opened his big mouth, asking for food. He was striving for life, and did not give up at all. Bird parents must be very hard workers, as these babies request a huge amount of food! But when Piolín's tummy was full, our friend simply started resting again.

There was a difference between resting alone and resting with mum: when he felt I was near, he used to tweet. When he felt he was alone, he used to keep quiet. Probably this is so, because he has to tell his parents in some way he is alive and OK. Otherwise, the parents could think he died, and so they would start worrying about the other babies.

But if you are a baby bird, and you are alone, you will get more chances to survive if you keep quiet, or otherwise you could be discovered by an undesired predator.

The experiment

Well, that was what I thought, but... was it really so? Or was just my imagination? After all this is a blog about experiments, no matter how simple they are. And every experiment needs an idea to check, predictions (we just guess something from our idea), measurements (to check if they fit what we predicted) and conclusions.

So, the idea to check here is:

A baby sparrow will tweet more often if he feels his parents' presence

The prediction is simple: if I touch Piolín, he will tweet more times per minute than if I don't. So, I started counting how many tweets he did per minute. In the next video you can see a sample:

Even if I was covering him with my hand, I was not pressing at all. I was just touching him.

And here are the measurements:

  • On my hand (covering him) > 38, 42 and 54 tweets per minute in three different moments

  • On my open hand (not covering him) > 18 tweets per minute

  • Touching him directly, while being in his nest > 65 tweets per minute

  • Touching him through some cotton in his nest > 63 tweets per minute

  • In his nest, not touching him > 0 tweets per minute

  • In his nest, not touching him, but with my hand near him (so he could perhaps feel my warmth) > 0 tweets per minute

  • In his nest, covered with cotton, but not touching him > 0 tweets per minute

  • In his nest, covered with cotton, two minutes after being touched by me > 26 tweets per minute

Every measurement has been made leaving enough time in between, so each time I started from "zero tweets per minute". This is important, as we will see soon that Piolín kept tweeting for a few minutes each time he had been touched.

And the conclusion: it is obvious that there is a big difference in his message if he feels the mild pressure of my fingers/hand than otherwise. By tweeting, he is trying to express something to his parents, probably just to let them know he is OK.

As I said, Piolín used to keep tweeting for a while after he was left alone (about two or three minutes). Here you can see him alone in the nest we made for him, a few minutes after the previous video (where he was in my hand):

What about Piolín?

Very unfortunately, this story has a very sad ending. He did not make it. The day later, while we thought he was sleeping, he started choking on his own vomit, and when we arrived it was too late. Everything happened in just five minutes. We felt really unhappy about this, but at least we gave him a chance and it has been a very enriching experience for us (even if it has been really exhausting, as they need to be fed every 20-45 minutes).

Piolín sleeping

However, if you ever find a baby sparrow, don't be discouraged, as you have many chances to help him become an adult, healthy sparrow. If you are in this situation, you can check these videos:

Video about a baby sparrow, with happy ending
Video about how to feed a baby sparrow
Video about how to make home made baby bird food
Eight baby sparrows asking for food!

Friday 21 August 2009

Baby bird communication (I)

Last month my sister brought a baby duck to my mother. Its name is Patxi (pronounced [patʃi]), and apparently what he (or she, but I will say he until we know what he/she is) loves most in this world is... tomatoes.

He probably thinks he is a human, as he has always been among humans. So, when there are no humans around he starts feeling scared of this dangerous world, and asks for help. In his language "help me, I am alone!" is translated into a siren-like shrill sound, while "I am OK and happy with you" is a normal ducky chirp.

This gave the idea to check for this experiment:

If a baby duck (grown up among humans) is left alone, he starts making a siren-like shrill sound to ask for help

Apparently this is quite simple. As any experiment should have at least some objective measurements, I timed the siren-like sound.

You can see the result in the following video.

I don't mention timing in the video, but you can see easily with a stopwatch that Patxi used his siren-like sound for about 24 seconds in four sessions.

Then I found something interesting: there is an exception to this. When Patxi is home, he does not feel scared of being alone (for him home means the plastic blue box). Even if I leave, he just calls mummy for a few seconds (about six seconds) and then he stops and continues doing whatever he was doing before (usually just chirping, pecking at things or... ehm... leaving his droppings around). Everything is explained in the second video:

As I show at the end of the video, funnily enough both places are in close proximity to each other.

So, by way of conclusion, we can make the following diagram:

I repeated the experiment several times, and many times there was not even "panic interval" when I left Patxi alone at home.

There is another experiment about baby bird communication I made. But that will be for the next entry.

Friday 1 May 2009

Eating uncooked lentils (postanalysis considerations)

If you think the previous experiment about eating uncooked lentils lacks of an essential condition every real experiment (either important or unsignificant) should have... In all likelihood you are right!

Everybody who agrees with the previous statement is invited to leave a comment in this entry telling us what was wrong in that experiment and why should it be indisputably repeated to be accepted by the very thorough referees of this blog (oh, yes, did you think anybody can write here? This blog is so tough that only experiments done by the referee himself are accepted!).

Thursday 23 April 2009

Eating uncooked lentils

I made an interesting experiment last year, but I never spoke about it. There is a lot of people who enjoy eating sprouts of different seeds. I was used to see in the local store soya bean sprouts and I sometimes ate them.

OK, but eating once more soya bean sprouts wouldn't be quite an interesnting experiment. I needed something different. So, let us try lentil sprouts. Huh? Am I forgetting something? Oh, yes... the hypothesis! A real experiment is just a way to check a first idea. Otherwise it is... OK, simply, it is something else. So here is the initial idea:

Lentils are edible without cooking.

Yes, lentils are rather hard if you don't prepare them. No good for teeth, for sure. So, I thought first I needed several days to grow them.

I remember I saw a friend who was growing sprouts: he used some kind of sieve in some kind of tupperware with water. This way the seeds kept the humidity and had space to grow at the same time.

I couldn't find something similar, but I had an idea: I could just use a clean towel on a pan. For some stupid reason I thought this was a wonderful idea. Don't do it, I will tell you later why...

Here is the set-up:

This was the aspect the lentils had on Day 0 (which was 3rd August 2008, at 9 pm):

Day 0; 9 pm

OK, nothing surprising for the moment. Everybody has seen raw lentils. On Day 1 I didn't take photos, so we will skip this, and we go straight to Day 2 (5th August):

Day 2; 5 pm

Here you can see the first white roots. They are alive! Nothing surprising: if 99.99% of the population has ever seen a raw lentil, probably 99.9% has already seen a growing lentil (leave a comment if I am wrong). On Day 3 (6th August) the experiment proceeded well:

Day 3; 5 pm

I remember I tried one of the lentils, and it was quite hard. Not edible yet. I was surprised, I thought it would take less time. "Give it another day" I thought. And this way we get into Day 4 (yeah, 7th August...)

Day 4; 5 pm

We can see on Day 4, for the first time, that most of the seeds have green tiny leaves. Photosynthesis is on! But seeds are still very hard. Hm... Am I going to need to cook this after all? So I left them there one more day.

This was what I got on Day 5 (8th August, just in case you lost count):

Day 5; 6 pm

At this point the plants were about ten times longer than the original seed diameter. You can check this wiht the first image of this post, as it has been taken on Day 5. Seeds were much softer. Here is what I got on Day 6 (ehm... 9th August):

Day 6; lunchtime

A wonderful lentil salad! I added some onions, tomatoes, parsley and dressed them with olive oil and salt. Probably pepper as well.

My impression: lentils are perfectly edible even when you don't cook them, but you will need around six days to be able to enjoy them. They have a strange texture in the mouth, I don't know how to explain it. It is as if they were kind of grainy when you chew them. But I think I could perfectly get used to this. And in some ways I think lentil salads are much better than lettuce salads.

Now... you remember when I said it was a stupid idea using a towel for this experiment? OK, here is why: I didn't know the roots of the plants were going to root so deep into the towel. They were amazingly strong! It was impossible to remove them completely, so some roots stayed in the towel. Additionally, the pan I used, after almost one week in contact with a humid towel, started to go rusty! This way, the towel blackened.

One less towel...

So if you want to reproduce this experiment... use a different system!

After this experiment I read a bit about lentil sprouts, and I discovered some wonderful properties they have. For example, they have a 25% of protein, lots of vitamins and three times more fibre than cooked (as they produce fibre while growing). Maybe I should restart growing them.

Enjoy your meal!