Dale Fort Blog Contents Numbers 1 – 29

10 01 2014

Dale Fort Blog Contents

Number 1

All about nematodes

https://dalefort.wordpress.com/2012/03/

Number 2

3 You Tube clips:

Starlings at Mabesgate

Error Bars in Excel 2007

Measuring Heights on Seashores

https://dalefort.wordpress.com/2012/04/02/dale-fort-blog-number-2/

Number 3

The History of Dale Fort part 1 (all about the rocks)

https://dalefort.wordpress.com/2012/04/03/dale-fort-blog-number-3/

Number 4

The History of Dale Fort part 2 (the construction materials of Dale Fort). Far more exciting than it sounds, you won’t want to miss it, go there NOW

https://dalefort.wordpress.com/2012/04/18/dale-fort-blog-number-4/

Number 5

Sargassum muticum in Britain (with a video on how it makes babies)

https://dalefort.wordpress.com/2012/04/25/dale-fort-blog-number-5/

Number 6

The History of Dale Fort part 3, The First Humans

https://dalefort.wordpress.com/2012/04/

Number 7

Silverfish and their ways

https://dalefort.wordpress.com/2012/05/10/dale-fort-blog-number-7/

Number 8

The fat-bellied book chewer

https://dalefort.wordpress.com/2012/05/

Number 9

Seaweed research at Dale Fort

https://dalefort.wordpress.com/2012/07/

Number 10

Wormhole research at Dale Fort

https://dalefort.wordpress.com/2012/08/07/dale-fort-blog-number-10/

Number 11

Limpets and their mysterious ways

https://dalefort.wordpress.com/2012/08/27/dale-fort-blog-number-11/

Number 12

Anne, Bridget, Cadoc and David

https://dalefort.wordpress.com/2012/12/07/dale-fort-blog-number-12/

Number 13

St David and his friend Elvis

https://dalefort.wordpress.com/2012/12/10/dale-fort-blog-number-13/

Number 14

Dancing bananas: Just how many are there?

https://dalefort.wordpress.com/2013/01/16/dale-fort-blog-number-14/

Number 15

Six-legged female vampires

https://dalefort.wordpress.com/2013/01/23/dale-fort-blog-number-15/

Number 16

Cry Havoc! And let loose the dogs of accountancy………The History of Dale Fort part 6

https://dalefort.wordpress.com/2013/04/22/dale-fort-blog-number-16/

Number 17

Wee timorous beasties

https://dalefort.wordpress.com/2013/04/30/dale-fort-blog-number-17/

Number 18

A magical island where strange events take place

https://dalefort.wordpress.com/2013/07/02/dale-fort-blog-number-18/

Number 19

The many faces of the mean (and by the way Bill, smoking is neither big nor clever)

https://dalefort.wordpress.com/2013/10/11/dale-fort-blog-number-19/

Number 20

Deviant Beards and other exciting topics

https://dalefort.wordpress.com/2013/10/11/dale-fort-blog-number-20/

Number 21

Welsh in 10 Minutes (ddim yn rhugl)

https://dalefort.wordpress.com/2013/10/24/dale-fort-blog-number-21/

Number 22

Halloween Special. Read it with the light on……..

https://dalefort.wordpress.com/2013/10/25/dale-fort-blog-number-22/

Number 23

Back to matters more prosaic but useful I hope. How to get a quick frequency distribution histogram out of Excel 2007

https://dalefort.wordpress.com/2013/11/06/dale-fort-blog-number-23/

Number 24

Spectacular weather, huge waves, the demise of a bridge, the scaring of a photographer and much more

https://dalefort.wordpress.com/2014/01/08/dale-fort-blog-number-24/

Number 25

BARNACLES so much more than just the worst part of a keel-hauling

https://dalefort.wordpress.com/2014/01/10/dale-fort-blog-number-25/

Number 26

NUNZILLA makes her debut: She knows about seaweeds, she’s a nun, she’s clockwork, she breaths fire. What more could you want? More history, that’s what and you’ll get it in Blog 26

https://dalefort.wordpress.com/2014/02/18/dale-fort-blog-number-26/

Number 27

TARDIGRADES…….No it’s not a Norwegian swearword. Their common name is water bears and they are astonishing creatures. Read about them and then construct your own with our free build your own tardigrade kit. Ordvykejys….now that’s a Norwegian swear word.

https://dalefort.wordpress.com/2014/02/21/dale-fort-blog-number-27/

Number 28

House Dust Mites…..I realise that it would be hard to top the spacetastic subjects of the previous blog but house dust mites are still extremely interesting creatures that eat human flesh and give you allergies. Read all about them here.

https://dalefort.wordpress.com/2014/03/07/dale-fort-blog-number-28/

Number 29

WOODWORM All you could wish to know and probably more about about the unsung heroes of the Anti-Furniture League

https://dalefort.wordpress.com/2014/03/11/dale-fort-blog-number-29/

Comments : Leave a Comment »

Categories : Uncategorized

Dale Fort Blog Number 25

10 01 2014

Barnacles

Barnacles might well be the best known of all seashore creatures. Along with limpets (see Blog Number 11 ) they are responsible for the distinctive grey band that is easily seen at low tide in the middle zone of most rocky shores.

Until the early part of the 19th Century most people thought of barnacles as little snails (like limpets). This was because they hadn’t looked at them properly. William Vaughan Thompson was as an Army Medical Officer but he’s remembered today for being the first person to describe the life cycle of a barnacle. In 1832 Thompson’s observations of the larval stages of barnacles placed them firmly in the Crustacea (animals with jointed limbs like crabs, shrimps and lobsters).

In 1854 Charles Darwin said this:

I hate a barnacle as no man ever did before

He had just completed 8 years of investigations which described every barnacle species, both living and fossil. The stress of examining microscopically around a thousand barnacle species and describing them all had taken its toll on his health. To produce this work Darwin had to write to scientists throughout the world requesting specimens, information and opinions. The result was a large network of informed people who admired and respected his views. Darwin was also probably the first person to describe a whole class of animals in terms of the species relationships with each other. There is no doubt that the barnacle work was what earned Darwin his scientific credibility. Without this, his much more famous book On The Origin of Species (1859) would not have had the massive impact that it retains to this day.

As Darwin discovered to his cost and benefit, there are many different kinds of barnacles. Happily for us we are likely to find only about 6 seashore species. Think of them as being like a tiny shrimp, with its head end glued to the rock, surrounded by armour plating. When the tide comes in the armour plating opens up at the top and the animal sticks its legs out and sweeps them through the water (something akin to the motions of fathers arms when dad-dancing at wedding receptions). Few people have ever seen this and it is well worth a look if you are on a suitable seashore (or wedding reception). Find a rock with some barnacles on it. Find a rock pool and stir it up a bit to liberate some food particles into the water. Put the rock in the pool, watch closely, (it might take a few minutes), be truly amazed and consider just how much water is filtered twice a day by the trillions of barnacles on seashores everywhere. These legs (the technical term is cirri) sweep water containing food down into the opening and into the mouth. Food is plankton (both animals like copepods and algae like diatoms) and dead stuff (detritus). The legs are bristly and can trap prey directly, some large barnacles can even catch fish.

Barnacles have interesting and very variable life cycles. The most common species on UK shores begin as planktonic larvae (floating about in the sea).

An early stage barnacle larva (nauplius = Latin for shellfish). It spends a few weeks in the open sea feeding on other plankton.

It then turns into a cypris (= Latin for Venus) larva, which settles out on the rocks and wanders about on its stumpy appendages looking for a place to settle. There’s a strong chemical attraction to adult barnacles. That little black dot is a light sensitive eye spot. If it wanders into dark crevice and/or detects other barnacles it gets very excited (in a special barnacley way) and ceases exploring. It then rocks back and forth and bashes that pointy lump on its front end (on bottom the left had side in the picture) on the rock. The little lump is a gland which eventually ruptures and releases barnacle superglue which glues the creature down.

The animal then sticks to that spot for the rest of its life. It grows armour plating (a shell or carapace) and becomes a mature adult after one to two years.

Barnacles have separate sexes and have to copulate to reproduce. This can be difficult if you are glued to the rocks surrounded by armour plating. How does a boy barnacle ask a girl barnacle out (as it were) given these circumstances?

The solution is spectacular. In Autumn, cooling sea temperature and rough waters cause the male barnacle to become aroused. He unleashes his mighty penis which is 8 or 9 times longer than his own body (proportionately the longest in the animal kingdom) and waves it around suggestively. It has sensory hairs on it which can detect female barnacles. When he finds a female (maybe as much as 5cm distant) he inserts it into her shell and fertilizes her eggs (up to 8000). She retains the fertilized eggs for the winter months before releasing them into the sea. Here they feed on the Spring bloom of plankton before settling and developing into adults (see above). As if that wasn’t thrilling enough, the Bohemian world of barnacles offers still more. The once proud organ withers and drops off and the male turns into a female for next year. If we multiplied the barnacle’s gentleman’s equipment up to human proportions it would be about 22 metres.

The technical expression for this type of reproduction is cross fertilizing protandric hermaphrodity. You might think this is an unnecessarily tortured phrase but it does describe the whole thing in only four rather obscure words and renders it all much less amusing. This is important because barnacle specialists get very annoyed when real people fall about laughing as soon as they hear about barnacles willies.