Translation guide
The English word 'dolphin' refers to the marine mammal. In Japanese, the most common and general term is イルカ. There is also a less common term 海豚, and a specific term for the dolphin fish (mahi-mahi) シイラ, which is not a mammal but is sometimes confused.
Referring to the aquatic mammal of the family Delphinidae.
The standard, everyday word for dolphin. Used in most contexts, including conversation, news, and education.
Referring to the fish Coryphaena hippurus, commonly called 'dolphin fish' or 'mahi-mahi' in English. Not a marine mammal.
The Japanese word for the dolphin fish (mahi-mahi). Important to distinguish from the mammal イルカ.
In English, 'dolphin' can refer to both the marine mammal and a type of fish (mahi-mahi). In Japanese, these are completely different words: イルカ for the mammal and シイラ for the fish. Using イルカ to refer to the fish will cause confusion.
昨日、水族館でイルカのショーを見ました。
Yesterday, I saw a dolphin show at the aquarium.
Dolphins are very intelligent animals.
The kanji representation of イルカ. Rarely used in modern writing; almost always written in katakana. May appear in literary or formal contexts.
Dolphins have been seen in Japanese waters since ancient times.
The dolphin fish is called mahi-mahi in Hawaii.