slowpoke

魚が泳ぐ速度は体の大きさだけではなく、体温にも関係があるようです。

Size matters for fast fish, but that’s not all

In terms of extended bursts of speed in the water, it is hard to beat fish belonging to the tuna and shark families. Using small monitoring systems attached to fish, researchers have learned that they swim nearly three times as fast as other species. These high speeds are attributed to a unique body system that has evolved to keep their body temperatures relatively high.

A research group led by Yuki Watanabe, an associate professor of marine zoology at the National Institute of Polar Research, compared the long-distance cruising speeds of 46 species of fish.

The results of the team’s research, released in a paper published in April last year on the Proceedings of the U.S. National Academy of Sciences, showed that a 428-kilogram great white shark swam the fastest at 8.1 kph, followed by a 240-kilogram bluefin tuna at 7.2 kph.

This compares with 3.1 kph of a 2.2-ton whale shark, a speed not unexpected considering its huge body. Sunfish and salmon were slowpokes: An 87-kilogram sunfish swam at 2.2 kph and a 3.3-kilogram salmon at 2.7 kph.

以下省略

http://the-japan-news.com/news/article/0003406339

今回取り上げる表現はslowpokeです。『ライトハウス英和辞典』（第5版　研究社）で調べると、可算名詞で「（米略式）のろま（人）」とありました。LDOCEには “someone who moves or does things too slowly” と定義されております。
Online Etymology Dictionaryで語源を調べてみると、 “also slow poke, 1848, American English from slow (adj.) + poke (n.3), the name of a device, like a yoke with a pole, attached to domestic animals such as pigs and sheep to keep them from escaping enclosures” という説明がありました。yokeが何をさすのかわからなかったため、画像を検索してみると、牛の首につける棒状の器具のようなもので「くびき」と呼ばれるものだとわかりました。これをつけて物を引かせると、歩く速度が遅くなることから、「のろま」という意味になったのではないかと思いました。（aqua）