SJP realised that the worm in the topsoil of the allotment was not the usual earthworm. It was though a different sort of worm, one which had us trying to remember all we could about platyhelminths, a phylum which last impinged upon our cerebral cortices 60 years ago. It is a New Zealand Flatworm, now named Arthurdendyus triangulatus, an invasive species that first appeared in Britain in the early 1960s, probably in the soil of imported plants. It has spread throughout the country and seems well suited to the damp (wet, to be honest) soil of Ayrshire. I am told it is particularly prevalent on some allotments because of a communal composting scheme that was in operation in the past.
It was put into the category ‘invasive’ because of the damage it can do to earthworm numbers and therefore soil quality and fertility. It apparently feeds almost exclusively on earthworms which are killed and digested outside the body. The flatworm wraps itself around the earthworm, extrudes its pharynx which produces digestive enzymes, and then ingests the resultant slurry (paté?) of earthworm. Earthworm populations may be reduced by 20%. As well as in soil it lives in damp laces above ground, around the bases of plants, under pots, stones, logs etc. In spring they lay egg capsules about the size of a blackcurrant. Each holds 5-8 young which hatch after two months.
It is forbidden under the Wildlife and Countryside Act(s) to distribute New Zealand Flatworms which means that any found have to be killed and not released alive.
This species was first described by Arthur Dendy (see here and here) as Geoplana triangulata in 1896. The eponymous genus Arthurdendyus was erected by Hugh D. Jones in 1999.
The mucus is said to be a skin irritant. However SJP survived unscathed from wrangling this most undesirable alien.
No comments:
Post a Comment