Pelagic is for things that belong to the open sea, far from land. A pelagic fish lives out in that wide water, not along the beach and not on the sea floor.

Pelagic遠洋 is for things that belong to是用來形容屬於 the open sea, far from land遠離陸地的開闊海域的東西 A pelagic fish遠洋魚 lives out in that wide water生活在那片廣闊的水域裡 not along the beach不是在海邊 and not on the sea floor也不是在海底

Scientists use it for the water column itself — the sea as water, from the sunlit surface right down — as long as they are not talking about the coast or the bottom.

Scientists科學家 use it for用這個字來指 the water column itself水體本身 the sea as water, from the sunlit surface right down也就是從有陽光的表層一路往下的海水 as long as they are not talking about the coast or the bottom只要他們講的不是海岸或海底

Though actually, learner books often gloss it as “deep-sea,” and that can mislead: a tuna racing near the surface in mid-ocean is pelagic even though it is not in the dark deep. The deep layers have their own pelagic names, but the core idea is “of the open sea,” not “of the trench.” It is a biology and ocean word, not everyday chat.

Though actually,不過事實上 learner books often gloss it as "deep-sea,"教材常把它解釋成「深海」 and that can mislead:這樣會讓人誤解 a tuna racing near the surface in mid-ocean在大洋中層、靠近海面疾游的鮪魚 is pelagic也算是pelagic(遠洋的) even though it is not in the dark deep儘管牠並不在黑暗的深海裡 The deep layers深海層 have their own pelagic names有自己的遠洋用詞 but the core idea is "of the open sea,"但核心概念是「屬於開闊海洋」 not "of the trench."而不是「屬於海溝」 It is a biology and ocean word這是生物學和海洋學的用詞 not everyday chat不是日常聊天會用的字

You also hear it as a noun for those open-ocean animals.

You also hear it你也會聽到有人把它 as a noun當名詞用 for those open-ocean animals指那些生活在遠洋的動物