Discussion:This is one several exclamation-point stories of Aldiss's. They seem over-the-top until you read them and understand the tone they're intended to be read.
There's an edgy experimentation going on, too--a little informal scatology and sexual reproduction. The switch between third and second person point of view. This may be meant to swing a finger on its readers (human, presumably). Weak creatures pretending to be strong with their guns: Prey upon nature, upset its balance at your own risk.
If one changes the ecology of a system, the system would need to adjust itself. Would the parasites leap off immediately? Maybe if there's a renewal process the ends upon death. Would the parasites leap on Claude? Maybe. Ticks, for instance, will go for any skin, but would parasites trade a thick for a thin one? It would depend on what they're thirsting for.
The prose here is richer than earlier efforts, the imagery more vivid, the irony thick as La Brea Pits' tar, but it isn't quite as thought provoking, perhaps inversely related to the images that impress. The ironic set-up executed at the finale, however, is well done.