Jellyfish – The Dominant Species
Read Jellyfish – The Dominant Species and check the IELTS Reading answers. Jellyfish have become the curse of beach holidays, permeating every ocean on the globe, thriving in the Arctic and the tropics. In an ever-changing world where other species struggle to endure, jellyfish populations are on t…
Passage preview
Jellyfish have become the curse of beach holidays, permeating every ocean on the globe, thriving in the Arctic and the tropics. In an ever-changing world where other species struggle to endure, jellyfish populations are on the rise. To the untrained eye, these creatures drift aimlessly on the oceans' currents and appear benign. In addition, they lack sharp claws, piercing teeth or even a brain. Despite this, they are armed with an amazing arsenal of weapons, especially the stinging power of their tentacles. As a result, jellyfish are among the most-feared, least-understood creatures in the seas.
Vocabulary from this passage
10 words worth learning before you sit the test, each with the sentence it appears in.
- an apt analogy noun phrase
A comparison that fits the situation well and explains it clearly.
In the passage:
"an apt analogy since the situation shares similarities with other monocultures" (paragraph F): the writer justifies the label.
Synonyms: a fitting comparison, a suitable parallel
Opposites: a poor comparison
- at the expense of adverb phrase
Causing harm or loss to something else while gaining an advantage.
In the passage:
"a massive population at the expense of other ocean life" (paragraph C): jellyfish gain while other species lose.
Synonyms: to the detriment of, at the cost of
Opposites: for the benefit of
- benign adjective
Harmless, not likely to cause damage, disease or trouble to anyone.
In the passage:
"drift aimlessly ... and appear benign" (paragraph A): jellyfish look harmless, but the writer then contradicts this.
Synonyms: harmless, gentle
Opposites: harmful, malignant
- gain a foothold verb phrase
To establish a secure position from which to grow or expand further.
In the passage:
"once jellyfish gain a foothold" (paragraph C): the first stage of takeover, before the population explodes.
Synonyms: become established, take root
Opposites: be driven out
- geographical range noun phrase
The whole area where a species is normally found living.
In the passage:
Q14 asks where the population "may spread"; the passage says climate change "may expand the traditional geographical range" (paragraph E).
Synonyms: population may spread, habitat
- keep in check verb phrase
To control something so that it does not become too large or harmful.
In the passage:
"small fish appear to keep jellyfish in check" (paragraph D): predation and competition limit their numbers.
Synonyms: control, hold back
Opposites: let spread
- proliferate verb
To increase quickly in number, often in a way that is hard to control.
In the passage:
Q20 asks about "an increase in jellyfish numbers"; the passage says "once we remove fish, jellyfish can proliferate" (paragraph D).
Synonyms: increase in jellyfish numbers, multiply
Opposites: dwindle
- speculate verb
To form an opinion about something without having enough evidence to be sure.
In the passage:
"Richardson and his colleagues speculate that climate change may expand" (paragraph E): a hedged claim, not a proven fact.
Synonyms: guess, theorise
Opposites: confirm
- stage a comeback verb phrase
To return to a strong position after a period of weakness or decline.
In the passage:
Q22 says fish are "unable to sustain their population"; the passage says it is hard for fish "to stage a comeback" (paragraph F).
Synonyms: unable to sustain their population, recover
Opposites: decline
- stem verb
To stop something harmful from spreading or continuing any further.
In the passage:
"swift, decisive action to stem the jellyfish takeover" (paragraph D): not the stem of a plant.
Synonyms: halt, curb
Opposites: encourage
Answers with explanations
- 14. E
Look for a prediction: a word like **could** and a direction. This section says **tropical species are moving towards the poles** and venomous jellyfish **could move into** more populated regions. That is a forecast of **the direction in which the population may spread**.
- 15. A
**Physical characteristics** means what the animal's body is like. This section says jellyfish **lack sharp claws, piercing teeth or even a brain** and have **stinging tentacles**. The other sections deal with numbers, causes, effects and advice.
- 16. F
**Lone survivors** means jellyfish that have taken over, the **jellyfish-dominated state**. Its **consequences** are that it **does not support** other fish, marine mammals and seabirds. The section about causes only warns that the ocean **might switch** to jellyfish; it does not describe what follows.
- 17. G
**Suggestions** matches **They recommend**. The list (stop overfishing, cut fertilizer and sewage, confront climate change) is how to **avoid further invasions**, and it sits in the section on **prevention**. The section on causes names the same problems but gives no advice.
- 18-19: CE
Match each option to a sentence. The jellyfish in the Black Sea devastated it by **feeding on anchovy eggs** that young fish rely on, which fits the decline in the anchovy population. **Financial hardship** matches **economic effect** and **millions of dollars in losses**. The shrimp option goes too far: fishermen are struggling, but no business is said to have shut down. Low oxygen is caused by algae blooms, not by jellyfish.
- 20-21: AB
Each correct option links to a human cause. **Overfishing** removes small fish that keep jellyfish in check, so **a shortage of small fish** lets jellyfish **proliferate**. **Fertilizer and sewage** put into the ocean match **the dumping of chemicals**. More competition among fish would do the opposite, because fish competition holds jellyfish down. Fewer seabirds and less biodiversity are results of a takeover, not causes.
- 22. eggs
**Unable to sustain their population** points to something jellyfish eat that fish need to reproduce. The text says they multiplied by **feeding on anchovy eggs**, so the gap needs **eggs**. Plankton is eaten too, but it is food the young fish rely on, not something that belongs to the fish.
- 23. monoculture
**Has been named** matches **has been defined as**, and **the main ocean species** matches the state where jellyfish become the **dominant species**. The name is in quotation marks, and the gap takes only its first word: **monoculture**.
- 24. nets
**Increasing numbers of jellyfish** matches **a jellyfish boom**, and **damage** matches **causing them to break**. What breaks is what the shrimp fishermen use: **nets**.
- 25. temperature
Basic facts matches **a greater understanding**, and suits them best matches **ideal**. Of the two things listed, only **water temperature** describes the ocean, so the gap needs **temperature**. Feeding habits is about food.
- 26. prevention
**Direct attention to** matches **focusing on**, and **instead of just trying to solve existing problems** matches **rather than cure**. So the gap needs the word before that phrase: **prevention**.