In this task, we ask you to rewrite a sentence in simple English without changing its general meaning. Essentially, you want to make the sentence easier to read by using simpler words, utilizing more straightforward sentence structures, and omitting non-essential information etc.

The family Argulidae contains the carp lice or fish lice a group of parasitic crustaceans of uncertain position within the Maxillopoda .
Fish lice are the family Argulidae , or ' carp lice ' .

The atomic radius of a chemical element is a measure of the size of its atoms , usually the mean or typical distance from the center of the nucleus to the boundary of the surrounding shells of electrons .
The atomic radius of an element is the distance between the nucleus and the edge of the electron cloud .

Informally , an expert is someone widely recognized as a reliable source of technique or skill whose faculty for judging or deciding rightly , justly , or wisely is accorded authority and status by peers or the public in a specific well-distinguished domain .
An expert is an individual recognized as a reliable source of knowledge or skill in a particular field .