A striking example of how man can drastically alter the interdependence patterns of ocean life has occurred off the coasts of southern California. In the nineteenth century, these waters had a large population of that busy little animal called the sea otter, which ate sea urchins*, which, in turn, fed on large brown algae called kelp.


Sea otters almost totally disappeared due to fur traders who encouraged hunters to kill off otters for their valuable furs. With the disappearence of the otter, sea urchins started to reproduce in vast numbers, leading to a great increase in their population. This caused sea urchins to almost entirely exhaust kelp beds. At this point, man had replaced the original balance of nature with a new pattern:

Patterns of Ocean Life
Ocean Life


The sea urchins, which previously had been the prey of the sea otter, had become the predator* and the kelp had become the new prey. As the kelp began to disappear, sea urchins began to starve. With the reduction of the urchin population, the kelp managed to reproduce and increase their numbers. Yet, the sea urchins again increased and so on.

A cycle taking from 10 to 12 years started to repeat itself. A further step came when sewage pollution caused an additional destruction of kelp – not because sewage kills kelp but because sewage  feeds sea urchins, which once again increased in numbers with this new source of food. If sea otters had been present in sufficient quantities, the kelp beds would still be abundant. In order to re-establish the proper balance in the eco-system, marine biologists have put forward a number of solutions. In time and with the help of man, nature may 25 regain its previous order.

The Ocean Life Patterns
The Patterns of Ocean Life

* sea urchin: a small ball-shaped sea animal with a hard shell and many sharp points * predator: an animal that lives by killing and eating other animals



A. What do the following refer to?
1. ‘these waters’ (line 3):
2. ‘this new source of food’ (lines 20-21):
B. Find words in the text which mean the same as the following.
1. change (paragraph 1):
2. completely, totally (paragraph 1):
3. use up (paragraph 1):
4. but (paragraph 1): 5. more than enough (paragraph 2):
6. propose, suggest (paragraph 2):
1. Why did the number of sea otters in California fall abruptly?
2. What was the cause of the exhaustion of the kelp beds?

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