Dale Fort Blog Number 1

26 03 2012

Welcome to the first entry in the new Dale Fort Blog.  On the grounds that most readers will not care whether I’ve just had a nice cup of tea or not, I thought I’d use the first of these blogs to write about interesting creatures.  This entry is about a group of animals that dwell virtually everywhere on earth (including inside your body).  I hope you enjoy reading about them and if it puts you off fish and chips, well that’s another blow struck for marine conservation.

Nematodes (or roundworms)

Towards the end of The Iron-Age when I was doing  A Levels, I came across a quote impressive enough to have lodged in my brain forever:

If all the matter in the universe except the nematodes were swept away, our world would still be dimly recognizable, and if, as disembodied spirits, we could then investigate it, we should find its mountains, hills, vales, rivers, lakes and oceans represented by a thin film of nematodes. The location of towns would be decipherable, since for every massing of human beings there would be a corresponding massing of certain nematodes. Trees would still stand in ghostly rows representing our streets and highways. The location of the various plants and animals would still be decipherable, and, had we sufficient knowledge, in many cases even their species could be determined by an examination of their erstwhile nematode parasites 

(N.A. Cobb, US Dept. of Agriculture, 1914).

Nematodes are possibly the most numerous of all multicellular animals.  They have been described as “a tube within a tube” because they are the simplest of creatures to have a discrete digestive tract and separate openings for taking food in and ejecting waste.  They are all over your house and inside your body and a handful of soil will contain billions of them. About 20,000 species have been described but it’s estimated that there might be half a million or so in total.  If you got access to a low power microscope, any fragment of moss dispersed in a little water will reveal worms like the one pictured above.

Free-living roundworms eat bacteria, fungi, animals, plants, foecal matter and other nematodes. Many are parasitic.  The biggest one ever found was parasitizing the pancreas of a sperm whale and was 8.5m long.  Some are responsible for hideous diseases in humans and other animals.  The gut-dwelling  Ascaris lumbricoides can reach 40cm long inside your digestive system. However appalling that sounds, it gets worse for the worm can then break through the gut-wall and wander around your body wreaking havoc.  Trichinella , a much smaller worm (3mm long) infects rats, pigs and humans.  If a pig eats an infected rat and a human eats the infected pig the human might be ingesting 40 million worms per 30g of pork .This leads to abdominal pain, diarrhoea and vomiting.  Male worms then copulate with the females who lay millions of eggs. The young migrate to the muscles and encyst (form a resilient resting stage) and you die.  Avoid all this with rat control, (pigs will relish a dead rat or 7) and thorough cooking of pig-swill and pork.  There are many more nasty nematodes:  The Guinea worm is feared in the tropics because it grows to 2m long and causes elephantiasis.  Less scary is the threadworm common in children.

These animals have occupied virtually every niche that can be conceived, from vinegar bottles to the tops of mountains, the tropics and the poles.  Without wishing to put people off, you can usually find some in between the muscle blocks of fish.  The cure for this is to eat your fish and chips in the dark.

Oddly enough, some of the more zoologically astute children of Coastland’s School in Pembrokeshire, UK use “NEMATODE!” as a term of abuse.  I don’t know the origins of this but there are 2 episodes of Sponge Bob Squarepants where Bob has to defeat a malicious round worm.

Visit this blog again for more stuff that isn’t about the weather or what I had for breakfast.

 

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