According to the speaker, what happened after sea otters disappeared from most of the coast?
Listen to an Oral Presentation · ELPAC Grades 9–10 listening. The correct answer, and the reasoning behind it.
A presentation on an academic topic, followed by three or four questions.
Listen to the student presentation. Then answer the questions.
The Otter and the Forest
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Good morning. My presentation is about one of the smallest marine mammals on the California coast, the sea otter, and why scientists call it a keystone species.
A keystone species is one whose effect on its surroundings is much larger than its numbers would suggest. Take it away, and the whole system changes shape.
Sea otters eat sea urchins, which are small, spiny animals that feed on kelp. Kelp is a giant seaweed that grows in underwater forests, and those forests shelter hundreds of kinds of fish and other animals.
When otters were hunted for their fur in the eighteen hundreds, they disappeared from most of the coast. With no otters to eat them, the urchins multiplied. They chewed through the bases of the kelp, and in many places the forests were replaced by bare rock covered in urchins. Divers call these places urchin barrens.
A small group of otters survived along the Big Sur coast. Once they were protected, they slowly spread. In the stretches of coast the otters reached, the kelp grew back. In stretches they did not reach, many barrens remain.
So when people ask why it matters to protect one small animal, my answer is that we are not really protecting one animal. We are protecting the forest it keeps standing.
The question
Choose the best answer.
According to the speaker, what happened after sea otters disappeared from most of the coast?
- Kelp grew faster because nothing was eating it.
- Fish populations grew because they had less competition.
- Otters from other countries moved in to replace them.
- Urchins multiplied and ate through the kelp, leaving bare rock in many places.Correct answer
Why “Urchins multiplied and ate through the kelp, leaving bare rock in many places.” is correct
This tests following a chain of cause and effect in the order the speaker gives it. Without otters, urchins multiplied; the urchins chewed through the kelp; the forests became urchin barrens. Students who reverse one link in the chain often choose a, so it helps to say the chain aloud: no otters, more urchins, less kelp.
Why the other answers are wrong
- Kelp grew faster because nothing was eating it. — Urchins eat kelp, so losing the otters led to less kelp, not more.
- Fish populations grew because they had less competition. — The kelp forests shelter fish, so losing the forests would harm fish rather than help them.
- Otters from other countries moved in to replace them. — The speaker says a small group survived at Big Sur and spread from there; no otters came from elsewhere.
Practice more of this
More listening practice for Grades 9–10, or see the ELPAC practice test for grades 9–10. For other grades, see free ELPAC practice tests by grade.
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