This is something I first noticed when I was at an aquarium in Japan (as evidenced in my examples) and continued to see ever since. There are certain pairs of animals, that while extremely similar, ...
Today I saw onigiri claiming to contain "しゃけ" (shake). When I asked my friend what that was, she said it was the same as "さけ" (sake), "salmon". So are these two just different readings of a kanji, ...
It seems that there are (at least) three words for "tuna" in Japanese: "マグロ" / "鮪" / "まぐろ" (maguro) - Seems to be the native name for the creature and used at least in sushi "ツナ" (tsuna) - Seems to ...