In a new study, shark researchers working off the eastern coast of New Zealand have found that three species of deep-sea shark are bioluminescent （生物性发光的），producing a soft blue-green light with specialized cells in their skin.

One of the species, the kitefin shark, grows to a length of nearly six feet, making it the largest known bioluminescent animal. The other two species are somewhat smaller than the kitefin, and all are occasionally caught as unintended by-catch by fishers. None are considered in danger of extinction, but little is known about their lifestyles and biology.

Bioluminescence had previously been documented in only around a dozen shark species, so this discovery significantly adds to our knowledge,^,, says Jerome Mallefet, lead author of the new study.

In the deep sea, where scientists estimate three-quarters of all creatures are bioluminescent, having the ability to create light can be extremely advantageous. In the depths of the ocean, which receives minimal amounts of sunlight, bioluminescent animals can hide themselves from enemies by producing enough light to match their surroundings. All three species examined in this study have large concentrations of photocytes （发光细 胞）on their undersides, which suggests that these sharks may hide from enemies in just this way.

"The discovery that these three species produce light is not surprising", says David Ebert, director of the Pacific Shark Research Center. That's because researchers think many more species of sharks are likely capable of producing light一Mallefet estimates that perhaps 10 percent of the 540 known species of sharks are bioluminescent. But Ebert thinks even this is far from the truth. "As the deep-sea shark research advances, that number will go even higher," he says.

Both Ebert and Mallefet hope that more attention will be paid to deep-sea sharks in the future, as the creatures and their habitat are understudied and under threat. "A lot of people know that sharks can bite," says Mallefet, "but few people know that they can produce light in the dark. ”

【小题1】What do we know about the bioluminescent shark species?

A．They were quite difficult to catch,

B．They preferred to live in the dark.

C．They were considered to be endangered.

D．They were little known about before the study.

【小题2】What does the fourth paragraph focus on?

A．The function of bioluminescence.	B．The significance of the discovery.
C．The terrible surroundings in the sea.	D．The usual activities of sea creatures.

【小题3】What does Ebert think of Mallefet's guess at the number of bioluminescent sharks?

A．Agreeable.

B．Scientific.

C．Inaccurate.

D．Inspirational.

【小题4】What is Ebert and Mallefet's common wish?

A．More people will study sharks.

B．Deep-sea sharks will grow in number.

C．Deep-sea sharks will receive more attention.

D．More bioluminescent animals will be found.