Direct links and indirect links in food web

[SheffieldWednesdayFC]

I'd like to know how to tell the difference between an undirected link and directed link in a food web. Undirected means that only a feeding relationship exists, but directed link indicates a flow of energy and matter between the species. I'm trying to find an example of undirected link.

In the diagrams it shows direct link as A--->B and undirected as A----B

[mith]

undirected links means there's a relationship but they're not sure how, at least that's the case for gene networks

[JackBean]

In the networks, undirected link usually means something like both directional flow, but in food web I can't much imagine, what could it actually mean.
Do you have some example?

[jwalin]

oh that didn't come to my mind



both sound true
an example will help.
sure you cannot be. but try you must

[BillPlant]

An indirect link occurs when the influence of one species, the donor is transmitted through a second species, the transmitter, to a third species, the receiver.

We see this a lot in plants - one species will rely on another species to keep their mutual pollinators.

Hope this helps!