Webbed feet vs. Webbing feet

[Guarana]

Would you explain the difference between webbed feet and webbing feet
with a long, elastic truck and............., the aquatic desman of Russia is one of the world's strangest looking insectivores.
A. webbed feet
B. Webbing feet

which one do you chose? i don't have an answer, and don't how to use v-ed and V-ing before noun.

Thanks for your support.
Guarana

[Torsten]

Webbed is an adjective that describes a netlike structure. The correct comination is webbed feet.
We use the past participle as an adjective here because it refers to a result - feet that look like a web.
We use the gerund as an adjective when we want to describe a process or something dynamic. Please take a look at these examples:

She is interested (in books, in languages etc.)
She is interesting (she interests others).

TOEIC listening, photographs: The Laboratory Screen