In-fauna (English spelling) infauna

...A unique community of terrestrial plants can be seen on the upper part of the sandy beach (such as sea bream, sea cucumber, and sea pea). The sandy area is home to large in-fauna such as bivalves and crabs, but they are fewer in number than in rocky areas. However, there are a significantly larger number of interstitial fauna such as tiny crustaceans, polychaetes, and nematodes in the sand.

*Some of the terminology that mentions "in-fauna" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…砂浜の上部には特異な陸上植物群落がみられる(ハマヒルガオ，コウボウムギ，ハマエンドウなど)。砂浜域には二枚貝やカニ類など大型の埋在性動物in‐faunaがすむが，岩礁域と比べて少ない。しかし微小な甲殻類，多毛類，線虫類などの間隙（かんげき）性動物interstitial faunaは砂中に著しく多い。…

※「in-fauna」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報