原田英語の時事英語ジュニア｜英語ニュース ワークシート（高校生レベル）
Class ____ No. ____ Name ____________________
シャチが海藻で道具づくり！ちぎった海藻で仲間の体をこすり合う
Kelp Tools and the Social Lives of Orcas
1Killer whales in the Pacific Northwest have been filmed making tools out of kelp and using them to groom each other. The findings were published on June 23, 2025, in the journal Current Biology. The research team came from the Center for Whale Research in Washington State and the University of Exeter in Britain.
2The whales belong to the southern resident population, which lives in the Salish Sea between Washington and British Columbia. A whale bites off the end of a stalk of bull kelp, a large brown seaweed. It then presses the piece against a partner, and the two whales roll it between their bodies for long periods. The researchers named this behavior allokelping.
3The team spotted it after buying a drone with a much sharper camera than their previous ones, even though the center has watched these whales for nearly 50 years. Whales of both sexes, all ages and every social group took part. They often paired with close relatives or with whales of a similar age. The researchers stressed that the whales were not just finding pieces of kelp but changing larger stalks to make the tools.
4There was some evidence that whales with more dead or peeling skin were more likely to join in, so the kelp may work like a body scrub. The researchers said the behavior may also strengthen social bonds between the whales. However, bull kelp forests are shrinking as ocean temperatures rise. The southern residents are also in trouble, with only 73 whales counted in July 2024.
Words 単語
| groomB1 | 動 | 体の手入れをする、毛づくろいするto clean the body or skin of an animal |
| populationA2 | 名 | （動物の）集団、個体群、人口all the animals of one kind living in one area |
| stalk外 | 名 | 茎the long main part of a plant |
| pressesB1 | 動 | 押し当てる、押すpushes something firmly against something else |
| behaviorA2 | 名 | 行動、ふるまいthe way an animal or person acts |
| previousB1 | 形 | 前の、以前のcoming before the one you have now |
| relativesB1 | 名 | 親せきmembers of the same family |
| stressedB1 | 動 | 強調したsaid strongly that something is important |
| strengthenB1 | 動 | 強めるto make something more powerful or firm |
| shrinkingB2 | 動 | 縮んでいる、減っているgetting smaller over time |
単語のレベル：CEFR-J（『CEFR-J Wordlist Version 1.6』 東京外国語大学投野由紀夫研究室. （URL: https://www.cefr-j.org/download.html より 2026年8月ダウンロード））
1. Reading Quiz 本文の内容に合うものを選ぼう
Where was the study published?
A. In a newspaperB. In the journal Current BiologyC. On a TV showD. In a school textbook
What does a whale do first to make the tool?
A. It bites off the end of a kelp stalk.B. It pulls a rock from the seafloor.C. It catches a fish.D. It breaks a shell.
What helped the team notice the behavior?
A. A new boatB. A team of diversC. A drone with a much sharper cameraD. An underwater microphone
Which whales were more likely to join in?
A. The fastest whalesB. Whales with more dead or peeling skinC. Only male whalesD. Whales from other oceans
Why are bull kelp forests shrinking?
A. Orcas eat too much of it.B. Boats cut it.C. People harvest it for food.D. Ocean temperatures are rising.
2. True or False 正しければ T、違っていれば F
( ) The researchers named the behavior allokelping.
( ) Only adult females used kelp tools.
( ) The whales often paired with close relatives.
( ) The southern resident population is growing quickly.
3. Fill in the Blanks 下の語から選んで空らんをうめよう（形を変えずに）
groomstalkbehaviorpressespreviouspopulation
The team spotted it after buying a drone with a much sharper camera than their _____ ones, even though the center has watched these whales for nearly 50 years.
Killer whales in the Pacific Northwest have been filmed making tools out of kelp and using them to _____ each other.
It then _____ the piece against a partner, and the two whales roll it between their bodies for long periods.
A whale bites off the end of a _____ of bull kelp, a large brown seaweed.
The researchers named this _____ allokelping.
The whales belong to the southern resident _____, which lives in the Salish Sea between Washington and British Columbia.
4. Word Order 語を並べかえて正しい文にしよう
( this / named / The / behavior / allokelping / researchers ) .
( every / group / both / sexes, / ages / part / social / took / Whales / of / and / all ) .
( as / shrinking / are / ocean / bull / forests / kelp / rise / temperatures / However, ) .
5. Think and Write 英語で答えてみよう
Many animals use tools. Do you think tool use is a sign of intelligence? Explain your view.（多くの動物が道具を使います。道具を使うことは知能の高さのしるしだと思いますか？意見を説明しよう。）
What could people do to protect kelp forests and the orcas that use them?（ケルプの森とそれを使うシャチを守るために、人間には何ができるでしょうか？）
Answers 解答
1. (1) B (2) A (3) C (4) B (5) D
2. (1) T (2) F (3) T (4) F
3. (1) previous (2) groom (3) presses (4) stalk (5) behavior (6) population
4.
- The researchers named this behavior allokelping.
- Whales of both sexes, all ages and every social group took part.
- However, bull kelp forests are shrinking as ocean temperatures rise.
全文訳
1北米太平洋岸北西部のシャチが、海藻のケルプで道具を作り、それを使ってたがいに体の手入れをする様子が撮影されました。この発見は2025年6月23日、学術誌「カレント・バイオロジー」に発表されました。研究チームは、ワシントン州のクジラ研究センターとイギリスのエクセター大学のメンバーでした。
2このシャチたちは「サザン・レジデント」と呼ばれる集団で、ワシントン州とブリティッシュコロンビア州の間のセイリッシュ海にすんでいます。1頭のシャチが、大きな褐藻であるブルケルプの茎の先をかみ切ります。次にその切れはしを相手に押し当て、2頭は長い時間、体の間でそれを転がします。研究者たちは、この行動を「アロケルピング」と名づけました。
3チームがこの行動に気づいたのは、以前のものよりずっと鮮明なカメラをもつドローンを買ってからでした。センターは50年近くもこのシャチたちを観察してきたにもかかわらずです。オスもメスも、あらゆる年齢、すべての群れのシャチがこの行動をしていました。近い親せきや、年の近いシャチと組むことが多くありました。研究者たちは、シャチがただ海藻の切れはしを見つけているのではなく、大きな茎を加工して道具を作っていると強調しました。
4死んだ皮ふやはがれかけた皮ふが多いシャチほど参加しやすいという結果も一部で出ていて、海藻はボディースクラブのような役割をしているのかもしれません。研究者たちは、この行動がシャチ同士の絆を強めている可能性もあると話しました。しかし、海水温の上昇にともない、ブルケルプの森は小さくなっています。サザン・レジデントの数も減っていて、2024年7月に数えられたのは73頭だけでした。
文法ポイント：比較級を強める much（much + 比較級）
比較級の前に much を置くと「ずっと～」と差の大きさを強調できる。本文の a drone with a much sharper camera than their previous ones は「以前のものよりずっと鮮明なカメラ」。very は比較級には使えない。
出典：Popular Science、FOX 13 Seattle ほか（記事は原田英語の時事英語ジュニアのオリジナル）｜https://www.haradaeigo.com/jijieigo-junior/news/2025-06-23-orcas-kelp-grooming-tools/