Why the physarum whitens?

[Gaspard Bébié-Valérian]

Hi everyone,

I'm observing the physarum growing and I've noticed something curious.

The Physarum is usually yellow as it grows but once it finds food, it tends to whiten and its branches sizes reduce too.

Is it normal or the symptom of any issue? Too much food or not enough? Too much light or too much humidity?

Many thanks for your feedback.

[ian]

That's actually the slime trail. As it explores physarum secretes slime, it'll spread out when it's looking for food but when it's located something it contracts down to the most efficient path leaving an outline of where it used to be 

[Gaspard Bébié-Valérian]

Thank you Ian. That makes sense now :)