What will you look for, to identify the sex of the following?

A male frog (Rana) can be distinguished from the female by the presence of sound-producing vocal sacs and also a copulatory pad on the first digit of the forelimbs. 

Claspers are present in the male cartilaginous fishes (e.g., Scoliodon) but not the bony fishes (e.g. Labeo). 

In Aschelminthes (e.g., Ascaris), often female is longer than male. 

In cockroach (Periplaneta), anal styles are present in the male but not the female.