Blood in the water

Whodunnit? The first time I saw these scarlet stains in a muddy stream where cows go to drink I was quite perturbed. Should I alert the farmer or call in CID?

But when I bent down and put my finger to the spots they disappeared, seeming to sink below the level of the mud. Peering as closely as I could to the water's surface I could make out tiny, waving, thread-like filaments that retreated when touched, suggesting these were micro-organisms of some kind, worms or larvae perhaps.

Professional ecologist Mollyblobs helped me to identify them as bloodworms or Tubifex - the name will be familiar to anyone who has kept goldfish since that's what they are usually fed on, in a dried form.

Tubifex, also called sludge worms, can survive in heavily polluted environments, such as drains and sewers, by waving their hemoglobin-rich tail-ends to exploit all available oxygen; like frogs they can exchange carbon dioxide and oxygen through their thin skin. Since they breed in vast numbers they can form huge clumps which have occasionally been mistaken for unknown life forms or alien creatures. It was such a discovery in a sewer that caused consternation in South Carolina a couple of years ago. So don't look at this if you are of a nervous disposition! Another clip here demonstrates how these worms behave out of water so as to create the impression of an amorphous throbbing organism.

Slightly disturbing to consider but if it feeds fish there's no reason why Tubifex protein should not provide human nutriment in times to come. If the world population continues to grow there'll be no shortage of shit for them to live on. Their main predator is leeches: all blood is welcome to them, whether it comes from kings or sludge worms.