What I mean is the case where the parasite does not contribute to the death of the host (tissue). Instead, the parasite may start growing after the host (tissue) is already dead.

I came up with this question when I was following the link in this answer and read the PDF about a fungus on a fungus on a fungus on a tree. In the PDF, the author first says that the Hypomyces was growing on the dead bracket mushroom, and then says again that Rhinotrichella globulifera was in turn growing on dead portions of the Hypomyces.

I'm not a mushroom expert and the author also does not mention whether the parasites caused the death of their respective hosts.

So suppose the parasites only started growing after the death of the host, do they really still count as parasites? My understanding is that a parasite should seek a host that is not dead and try to leech nutrients without killing the host too quickly (at least until the parasite is ready for the next stage of its lifecycle and no longer needs the host).


In parasitic interactions, one species (the parasite) benefits from the interaction while the other (the host) is harmed. So, whether an interaction is parasitic or not really depends on whether on the host species is harmed by the interaction. If something only grows on the dead remains of another organism, but causes no harm to living organisms in terms of growth and reproduction, it would not be a parasite, and might actually be beneficial to that organisms in some ways.

However, dead cells or tissues are not always useless to a still living organism. For example, the vast majority of cells in a mature tree are dead, but are still important for the survival of that tree by providing structure and water/nutrient transport. A hypothetical parasite could feed only on the dead cells inside of a tree and still cause harm to that tree by weakening it's trunk or impairing it's ability to transport water and other nutrients.

Not knowing much about fungal physiology myself, I can't say whether these "hyperparasites" are truly parasitic or not. But it is at least feasible for a parasite to only grow on the dead portions of a host and still cause it harm.


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