Also known as Slime Fly, drain fly, filter fly, sewage fly, or bathroom fly. The genus that turns up in most complaints is Clogmia, which is the most awesomely appropriate name for a fly that breeds in drains EVAH.
Fruit Fly Brain by Christian Klambt and Imke Schmidt: This image of a fruit fly brain was created by marking the structural proteins of the cells. It shows the developing eye disks as well.
Wasp has hints of a clockwork brain
The greenhouse whitefly parasite (Encarsia formosa) is just half a millimetre in length. It parasitises the larvae of whiteflies and so it has long been used as a natural pest-controller.
To find out how its neurons have adapted to miniaturisation, Reinhold Hustert of the University of Göttingen in Germany examined the insect’s brain with an electron microscope. The axons - fibres that shuttle messages between neurons - were incredibly thin. Of 528 axons measured, a third were less than 0.1 micrometre in diameter, an order of magnitude narrower than human axons. The smallest were just 0.045 μm (Arthropod Structure & Development, doi.org/jfn).
That’s a surprise, because according to calculations by Simon Laughlin of the University of Cambridge and colleagues, axons thinner than 0.1 μm simply shouldn’t work. Axons carry messages in waves of electrical activity called action potentials, which are generated when a chemical signal causes a large number of channels in a cell’s outer membrane to open and allow positively charged ions into the axon. At any given moment some of those channels may open spontaneously, but the number involved isn’t enough to accidentally trigger an action potential, says Laughlin - unless the axon is very thin. An axon thinner than 0.1 μm will generate an action potential if just one channel opens spontaneously (Current Biology, doi.org/frfwpz).
“That makes the axon impossibly noisy,” Laughlin says. Any “legitimate” action potentials will be drowned out.
Hustert suggests that a neuron might get around this problem by firing bursts of action potentials to cut through the noise, but Laughlin is sceptical. “They’d be firing furiously all the time,” he says, and every action potential costs energy.
Instead, the neurons might not bother with conventional action potentials at all. “They could be sending signals mechanically,” Laughlin says. The tiny axons might each carry a long rigid rod stretching down the centre. Pulling the rod could create a physical rather than electrical trigger for the release of a chemical that passes the signal on to the neighbouring neuron.
In larger animals this would be far too slow, says Laughlin, but in the tiny body of the greenhouse whitefly parasite, a partly “clockwork” brain might be the best approach.
A newly discovered species, Euryplatea nanaknihali, is the world’s smallest fly, and has the rather unsavory habit of biting off the heads of ants, according to a paper in the latest issue of the Annals of the Entomological Society of America.
At just .4 millimeters in length, the fly is only a fraction of an inch in size. A house fly is 15 times bigger. A fruit fly is 5 times larger.
