vulgar, wanton, low, many, varied
猬 centers on low, crude, or excessive behavior: something vulgar, wanton, or base. The senses of 'many' and 'varied' likely extend from the idea of an unruly, overflowing mass.
猬 combines the animal radical 犭 with 胃, but the historical role of 胃 here is uncertain. It may have originally been a phonetic component or a semantic extension, but the exact development is unclear.
A beast (犭) with a stomach (胃) that is never satisfied, acting vulgar and wanton, gorging on many varied things.
For イ, imagine an eagle (イーグル) behaving in a vulgar, wanton manner, snatching many varied prey with its stomach always hungry: eagle -> イ.