Tag Archives: land planaria

Bipalium between the rains

16 Jul

Hi blog.

July started as a major disappointment – it rained every day for the first eight days of the month.  Our grand total of sunshine during that period was 24 minutes!  Temperatures dropped to the low twenties, and people were catching colds.

Then on July ninth, the rain stopped.  And we had no rain for almost a week.  Temperatures rose to the low to mid 30’s, and I laughed as the local population were struggling to cope.  (Someone at work even ventured that the Tokyo area must be the hottest metropolitan area in the world – I resisted the temptation to tell him of a week in Adelaide when the minimum temperature was above 30°C, or of an exercise I did with the army where it got up to 47°C!)

Problem: “It’s so hot!”

Solution: “Harden up!”


Anyway, it was on the morning of the 9th that I spotted this particular beastie.  I’ve written about its close relatives in a previous post, but I thought I’d better get a shot of this one just to give you some idea of the size.  (Note: this is not the biggest one I’ve seen – that particular individual would have been close to 60 cm!)

You could walk right past this and never notice it – and most people do exactly that.

No, I didn’t nearly put my foot in it – that’s for scale. My shoe is about 30 cm long, making that planaria about 40 cm.

Bipalium nobile (sorry, there doesn’t appear to be a common name in English) is known locally as omisujikogaibiru (大三筋笄蛭), and is an invasive species.

The business end of the planaria. You can see why they are sometimes known as arrow-head worms. You can also make out the three lines with give rise the the Japanese name for this species.

Being fairly aware of the problems invasive species can cause, as well as practical, I photographed it and then put in my eel tank.  Saving the environment AND reducing the costs of feeding my eel.  Practical indeed.

As I write this, typhoon number 11 is making its way towards eastern Japan, dumping an entire Adelaide annual rainfall in just a few hours, and we can expect more heavy rain during the next 48 hours or so.

Maybe I should build an ark, just in case…


Quick profile: Land planaria

15 Nov

Land planaria, sometimes known as arrow-head worms or hammer-head worms, of the genus Bipalium.

Its Japanese name is kogaibiru (笄蛭), named after an ornamental hair pin.

This is a predatory flatworm.  It feeds on earthworms, snails and slugs.  Some species are invasive – Bipalium nobile, which can reach up to 1 metre in length, for example.


Land planaria spotted on the footpath on November 12, 2011. The shape of the head is reminicant of old style hair pins, hence the name kogaihiru (lit. “hairpin leech”). It is not a leech, but a kind of flatworm.

Primarily nocturnal, and living underground or under leaf litter, this is a creature that is frequently close to human habitation but generally escapes notice – few Japanese people I’ve talked to know of its existence.

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