Dizzi discovered a new worm, sent a picture and asked: ‘Pete – What is this? Hamerkop Worm? About 5cm long.’
I didn’t have a clue, and guessed – incorrectly – that it might have been from the dogs. But Dizzi soon came back with an answer: Bipalium – a genus of large predatory land planarians. They are often loosely called “hammerhead worms” or “broadhead planarians” because of the distinctive shape of their head region. So Dizzi’s description was spot-on!
Land planarians – flatworms – are unique in that they possess a “creeping sole” on their ventral (‘under’) side. And they’re hunters! They’ll stalk their prey, following their tracks and then pounce on an earthworm or snail! Some earthworms will react violently and wriggle vigorously, but the Dizzi planarium bipalium flatworm uses the muscles in its body and sticky secretions to attach itself to the earthworm to prevent escape. A wrestle-and-kiss tactic! Some even have a potent neurotoxin, so goodbye earthworm or snail.
Maybe Dizzi will spend more time in her garden and film a planarian kill for us?
They vary in size from smaller than this one to over a metre. They have very few predators themselves as they seem distasteful or toxic to most other creatures. Wonderful where they belong, but can be a menace when introduced where they don’t. They’re found all over in the tropics and sub-tropics, and are now spread outside their natural areas too – mostly moving around in potplants or plant soil.
Asexual planarians can just split and form two planarians. Sexual planarians are hermaphrodites. Some can reproduce both sexually and asexually. Telling a planarium to ‘Go Fuck Yourself ‘ is pointless, as it might just do that – ‘autofecundation.’ That’s rare, though. Usually two hermaphrodites will get together and swop sperm.
So I go looking for worms and the further I dig the less simple and – as with most things where we Homo sapiens involve ourselves – the more disheartening it gets!
Earthworms. Everybody loves earthworms, right? They do so much good . .
Well yes, earthworms do much good where they belong. But where they don’t belong they do much harm. Up in the northern hemisphere the boreal forest — the world’s most northerly forest, which ‘circles the top of the globe like a ring of hair around a balding head,’ shouldn’t have earthworms, and the introduced worms are causing a huge problem. Worms have been moved around the earth by man since we started traveling. In soil, plants and pots for plants; by air, sea and road, in moving timber on trucks, in the tyre treads of those trucks and cars, in boats, by anglers and by gardeners.
One researcher called it Global Worming! Which may add to global warming. The boreal forest is a carbon sink, but the earthworms may alter it to emitting carbon instead.