I WONDER - Why Are Some Amphibians So Brightly Coloured?

The video discusses how animals use coloration for survival. Tropical birds use colorful feathers to attract mates, while polar bears use white fur for camouflage in snowy environments. Amphibians use bright colors to signal danger, as many are poisonous.

What does it indicate when amphibians have brighter colors?

Why are many brightly colored amphibians considered dangerous?