Interesting creatures seem to be following me around. This time though it’s not just interesting, it’s very unusual.
I came in my front door one day, and picked up off the floor, what I thought was a small scrap of paper, but when I touched it, it was moist and sticky, and it moved. It was a bit like a worm or a leech, but white, and only dragged itself along like a slug. After unfruitful searches on the Internet, I again sent pictures to the museum.
Flatworm from above
Flatworm from below
The museum’s curator of invertebrates sent them to an expert at James Cook University, Queensland, who gave a very detailed response. The details of my find, including pictures, will be put on Bowerbird, a biodiversity information-sharing website, and from there on to the Atlas of Living Australia. Here is the university’s information:
“Many thanks for your email and the interesting images. I think that your guess as to the identity of the specimen is correct – possibly a juvenile bipaliinaeid, Diversibipalium sp. (Platyhelminthes: Tricladida: Continenticola: Geoplanidae: Bipaliinae). Alternatively it could be an as yet to be formally described “Thosteelia” (paper in preparation), a white native Australian species about 15 mm long that I have recorded from only one location, at Table Cape in Tasmania. It too has a semilunate head (though not as pronounced as in the Bipaliinae), with three, dark, longitudinal stripes, and it has an adhesive patch under the head (see attached images).
Bipalium kewense, the Shovel-headed Garden Flatworm (see page 18 of “Melbourne’s Wildlife”) is found in urban and public gardens in Australia. The juveniles of this species are cream-coloured just after hatching from their cocoon, and may exhibit faint greyish markings corresponding to the “collar” around the neck, and on the head plate.
The specimen in the photograph exhibits a faint median dorsal line, and this would be consistent with the markings of B. kewense, though the white body and absence of an indication of the collar raise a slight doubt. Under a hand lens, multiple, minute black eye spots should be able to be seen contouring the margin of the head plate, and concentrating at the neck before passing along the sides in a species of Diversibipalium, but in the Australian species there is a single row of eyes contouring the tip, slightly crowding at the side, then continuing along the body to the end in a staggered row.
As Mr Tucker notes, the flatworm may have come on their clothing or the dog. Flatworm secretions are sticky, and in the past, finding the flatworms around the anal area of a dog has raised questions about parasitism, though when investigated, the situation is best described as “pseudoparasitism”. The beach would be a hostile habitat for most land planarians, though I have found some native species under vegetation at the base of cliffs of rocky surf beaches; I have not found introduced species of land planarians in this habitat.
It would be interesting to know whether Mr Tucker has a hothouse or garden with potted plants or microhabitat conducive to flatworms. A juvenile land planarian that small, must have come from a cocoon, and to date the only records I have of sexual B. kewense are from Perth, Brisbane and Charters Towers. I would have expected that specimens of B. kewense living out doors in Anglesea would be more likely to reproduce by fission – shedding the last centimeter of their body following a lovely meal of a luckless earthworm. The shed portion crawls off and regenerates into a whole flatworm. The juvenile in the photos you have sent looks more like a hatchling from a cocoon. Autumn is the time when native land planarians mature and lay cocoons. There remains the possibility that the species is native similar to my Table Cape beast.”