milk shark
A small species of requiem shark (Rhizoprionodon acutus). The name is usually written in katakana.
The milk shark is a small shark that inhabits shallow coastal waters.
Katakana spelling is common for this fish name; usually written in kana.
Kanji form exists but is rarely used; the word is usually written in kana.
The name ヒラガシラ literally means 'flat head', referring to the shark's head shape. The exact derivation is uncertain.