This image of baby leaf veined slugs, taken by evolutionary genetics Ph.D. student David Winter, is oddly adorable. And Winter's story of his quest to figure out what leaf veined slugs eat is oddly fascinating. Apparently, there's a surprising amount we don't know about slug behavior. Slug diets, in particular, are a black box about which very little is definitively documented.
Sure enough, searching through the literature on the 30 or so species of leaf veined slug in New Zealand, there is no indication of what it is that they eat. That was too depressing for me, we know so little about the biology of our native invertebrates, but this species (Athoracophorus bitentaculatus) isn't particularily rare, we should at least know what this one eats.
So, I took to stepping outside an night time, finding a couple of slugs, and placing them in a bucket. In the morning I'd move them back to the shrubs from which they'd been plucked and collect [from the bucket] a few fecal samples to inspect ...
The Atavism blog: The Sight of a Wild Slug Eating