Author: Andrew

Tarantula spider facts

Tarantula spider facts

Vulnerable spiders?

spider fangs
Tarantula spider fangs (family Theraphosidae). 80015175

Despite being a predatory animal, the spider can also be predated upon.  With tarantulas, their major predator is a large member of the wasp family Pompilidae.   The larger of these wasps are known as “tarantula hawks”.  They will track down a tarantula using their sense of smell and paralize it dragging it back to its burrow.  The wasp then lays an egg on the hapless tarantula’s abdomen then seals the spider in its burrow and goes off to find more prey.  The wasp larva then hatches and feeds on the spider.  Another known predator of

spider hair
Urticating hair of mexican red knee tarantula. 80201750

tarantulas are giant centipedes, particularly Scolopendra gigantea.  This species is known to be a very aggressive carnivore that will attack and eat almost anything it comes across including tarantulas.   In some parts of the Americas, tarantulas are classed as a delicacy.  They are quite often roasted over an open fire to remove the hair before being consumed.

Urticating hairs of the Brachypelma smithi tarantula

Urticating hairs
Adult female Brachypelma smithi, showing a bald patch after kicking hairs off of her abdomen.

Some of the “new world” tarantulas have two major defence systems, the obvious being venom but also they have special hairs on their opisthosoma or abdomen known as urticating hairs.  When in fear of attack, they will rub their hind legs against their abdomen flicking these urticating hairs at the enemy.  The tiny hairs or bristles get into the skin and mucous membranes of the attacker and can cause much irritation and even edema which is sometimes fatal.  Studies on these special bristles indicate that they cause both mechanical and chemical harm to the membranes and skin.  After kicking off the hairs, the tarantula will have a bald patch on its opisthosoma.  The hairs will not grow back but will be replaced when the spider next moults.

Then and now…

Then and now…

then and nowImagine, in the beginning, when calculators, computers, digital cameras and horror of horrors, mobile phones didn’t exist. Indeed, if you had a telephone it came attached to a house by a long black cable and the only thing you could do with it was make a telephone call.

Only 3 channels on TV!

Imagine also there being only 3 television channels to watch, in black and white of course, with no chance of recording a programme in the unlikely event of a clash as even an affordable, commercially available video tape recorder was a futuristic dream by some years.

CD and DVD were just letters

stylus
stylus in record groove. 80001165

CD and DVD were just letters of the alphabet, digital and binary were terms used solely by academic mathematicians who could only cope with two numbers and the nearest thing to software was hardware, a shop down the road that sold coal shovels. Nor would you have a computer or tablet on which to read this. A place of nightmares for most early 21st century youngsters who find it impossible to live without their mobile phones, iPads and Xboxes. No, this was not millions of years ago when dinosaurs ruled the world, it was how life was in 1965 on planet Earth.

Then…

electric razor
Electric razor detail. 80019148

However, during those dark mediaeval times, the Telegraph newspaper published a colour supplement magazine with photographs the likes of which had never been seen before by the general public. A dentist’s drill looking like something a car mechanic might use; a length of double-coiled cable that might have once adorned a hair drier, in reality a filament from a light bulb; a shaft of beard hair resembling the trunk from a New Zealand tree fern and a piece of trawlerman’s net that turned out to be the knitted fibres of a nylon stocking.

It was inspirational!

The images astounded many and certainly fired the imagination of a youngster I once knew to try and follow some form of scientific career. All the micrographs had been produced using a new type of microscope, the first commercially available scanning electron microscope (SEM), manufactured by Cambridge Instruments and marketed as the Cambridge Stereoscan.

…and now

velcro
Velcro hooks. 80016907

The micrographs were stunning and certainly hard won though by modern standards now appear dated. These days the use of scanning electron micrographs to illustrate or enhance many a literary work is commonplace and almost obligatory but the age of digital photography has to a considerable extent and much regret, devalued their status.

Of little value

With so many of the population owning a digital camera (or perhaps more accurately, an image capturing device) in one form or another ready to ’snap’ the most trivial of subjects, the average person now attributes little if any value to most images. The work and expertise required to produce any high-quality image is lost or ignored. A consequence of this is that many images are being stolen and freely distributed over the worldwide web without any consideration of copyright, the work or even the cost having gone into producing them.

chromosomes
Group of human chromosomes
IMAGE REF: 80200675

Left is an image of human chromosomes cultured, extracted and isolated from leucocytes (white blood cells). Cost to produce, over £1,000 in consumable supplies and many hours of complex work, these images are a far cry from a simple ‘snap’ taken with a point-‘n’-shot mobile phone camera or something similar.

 

She sells sea shells…

She sells sea shells…

The loneliness of the long-distance beachcomber. A bleak, deserted,
windswept beach along the west Wales coastline.

Whilst we are all aware of sea shells on the sea shore and probably without exception have taken home the odd one or two as mementoes of a particular holiday, how many of us appreciate that more often than not we are tramping over myriads of shells we didn’t even know were there. Above is a photograph of a delightful sandy beach along the Ceredigion coastline; at low tide miles of flat sand with occasional patches of ripple marks. At some time or another throughout the year most flat, shallow-gradient beaches exhibit white streaks running parallel to the sea. Sometimes these streaks can be very extensive, as seen in the photograph above, which is a perfect example of the natural grading of sand by wave action where light material is ‘panned’ or sedimented above heavier particles of the sand itself. When examined with a hand lens, the content of these streaks will be seen to comprise largely of a miscellany of broken shell fragments and sea urchin spines. When examined more closely though with a microscope, a multitude of sub-millimetre shells comes into view.shells

Mixed foraminifera tests (shells) collected from the beach above.
Width of image represents 4.4mm

These shells are the remains of microscopic organisms known as foraminifera which belong to the phylum of Protozoa that includes paramecia and amoebae. These organisms are an important component of marine plankton and upon their death the shells (more correctly known as tests) sink to the sea floor forming vast deposits. The word foraminifera means hole-bearing as the tests of most species are perforated with holes through which the amoeboid organism extrudes pseudopodia used for trapping food particles in the water column.shellshellshell

Detail of tests showing foramina (perforations).

Flame Ionisation Microscopy – Robert Hooke’s Microscope

Flame Ionisation Microscopy – Robert Hooke’s Microscope

Originally this was going to be one of those corny 1 of April spoofs, hence the title, for all those devotees who revel in such matters but then I decided this was not a subject for such brevity. Robert Hooke is one of two founding fathers of microscopy and should be respected for not only being such but as probably one of the most learned and accomplished scientists of his time. During January 1665 Hooke published, through the Royal Society of which he became Curator by Office, his book entitled Micrographia. Throughout he makes detailed accounts and observations of common objects viewed through one of his microscopes in addition to superbly drawn illustrations which must have amazed everyone who thumbed its pages. He had presented to the world a view of a microscopic world never seen by anyone before.

Above is a representation of Hooke’s microscope, modelled in Blender 3D, from the line drawing (Schem:1, Fig:5 and Fig:6) depicted in Micrographia. For all its inaccuracies and artistic licence, visualising a 3D representation helps put the individual components into context.