noun
great seahorse; Kellogg's seahorse; offshore seahorse
Refers specifically to the species Hippocampus kelloggi, a large seahorse found in the Indo-Pacific. In Japanese, the katakana name is the standard form.
オオウミウマはインド太平洋に生息する大型のタツノオトシゴの一種です。
The great seahorse is a large species of seahorse that inhabits the Indo-Pacific.
タツノオトシゴ is the general Japanese word for 'seahorse', while オオウミウマ is a specific species.
Compound of 大 (おお, 'big') + 海馬 (うみうま, 'seahorse'). The kanji 海馬 literally means 'sea horse'.