The Narwhal's Sensitive Tusk
Written by Studio AM.
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A narwhal's tusk is a tooth, usually a male’s left upper canine, that grows outward in a long spiral. Females can also grow tusks, and rare individuals have two. Its structure raises questions about function. The tusk contains pathways connected with nerves, and tiny channels link its inner tissues with surrounding seawater. Experiments and anatomy suggest that it can provide sensory information about the environment. Changes in salt concentration may produce responses, for example. Researchers still study how narwhals use it.
Sensory ability is probably not the tusk's only significance. Males may cross or rub tusks, and observations connect it with social display and competition. On rare occasions narwhals have been recorded striking fish with tusks. One behavior does not establish a single universal purpose.
The animal lives in Arctic waters, navigating sea ice and finding prey at depth. A sensitive tooth may carry information unlike vision or hearing, but a useful feature can serve several roles. The same structure may contribute to sensation, feeding, and social behavior.
Caution matters because narwhals are difficult to observe for long periods beneath ice. Evidence comes from anatomy, controlled tests, tags, and limited direct behavior. The best account holds these sources together: the tusk is living tissue capable of sensation, strongly shaped by sex and social life, and still not fully explained.
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Questions
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Question 1 of 4
What is the main idea of the passage?
The answer is C: The narwhal tusk is a living, nerve-connected tooth with sensory and social roles that evidence has not yet reduced to one purpose.
The passage combines anatomy, experiment, behavior, sex differences, and limits of observation.
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Question 2 of 4
Why is it difficult to identify one purpose for the tusk?
The answer is D: Several evidence types suggest different roles, and narwhals are hard to observe beneath ice.
Multiple plausible functions and limited long-term observations prevent a simple universal conclusion.
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Question 3 of 4
What does “canine” mean here?
The answer is A: a type of tooth in the upper jaw
The opening identifies the tusk as the left upper canine, explicitly making it a tooth.
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Question 4 of 4
What environmental change may the tusk detect?
The answer is B: a change in salt concentration
The first paragraph uses salt concentration as an example of a possible sensory response.
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