also: うみうま
Common name for the marine fish. The reading かいば is standard; うみうま is a rare alternative.
See also: タツノオトシゴ
I saw a seahorse at the aquarium.
hippocampus
Only with reading かいば
Anatomical term for the part of the brain. Only read かいば.
walrus
Only with reading かいば
Rare alternative name for walrus, usually called セイウチ. Only read かいば.
See also: セイウチ
The hippocampus plays an important role in memory.
In old documents, 海馬 can refer to a walrus.
hippocampal formation
parahippocampal gyrus; hippocampal gyrus
parahippocampal gyrus
hippocampus
Standard kanji spelling for both the seahorse and the anatomical hippocampus. The reading うみうま is also possible but less common.
Kun'yomi reading for the seahorse sense; rarely used in modern Japanese.
Sino-Japanese compound 海 (sea) + 馬 (horse), calque of the seahorse's shape. The hippocampus sense is a direct borrowing of the anatomical term, which itself is named after the seahorse-like shape of the brain structure. The walrus sense is an archaic usage, possibly from a different etymological association.