Stingrays are an instantly recognizable fish, with their pancake-like bodies that swim gracefully through the water. Their flat bodies allow them to sit on the bottom of the ocean, river or lake, disguising themselves to predators (食肉动物) swimming above as they hunt their prey (猎物) on the floor. Their eyes sit on the top of their body, while their mouths are on the bottom. They each have a long tail with a toxin-filled barb (充满毒素的倒钩). When they feel threatened, they can lift their barbed tails upward and injure potential predators. Most species of stingrays sport dull colors that help with disguise, though some do have more lively colors. Stingrays eat prey like worms while freshwater stingrays eat insects as well.

As those creatures move through the water, they generate bioelectric fields. Stingrays are able to detect these bioelectric fields of the animals around them using a network of special sensory organs called ampullae of Lorenzini. These organs are small, fluid-filled electrical receptors that are located near the stingray's mouth and look like tiny black holes in the animal's skin. Once they've located and captured their prey with the help of these sensory organs, stingrays use their hard teeth to break the shells of their victims, and can even chew their meal.

In 2006, Australian television personality Steve Irwin died when a stingray's barbed tail pierced his heart. Irwin was being filmed for a show called "Ocean's Deadliest" when he swam too close to a stingray. However, death from stingrays is rare. A stingray's poison is generally only deadly when its barb pierces people's neck or chest. Otherwise, contact with a stingray's. barb anywhere else on the body causes pain similar to a jellyfish (水母) sting.

Scientists also believe that stingrays have the ability to detect the Earth's magnetic fields and the orientation of electric currents generated by objects in the water. They could then use that information to navigate in the open ocean. However, this ability could potentially cause problems for the animals as offshore energy technologies like wind and wave energy become more popular, thus disturbing stingrays' ability to accurately detect their surroundings. This could influence stingrays' feeding and migration patterns.

【小题1】What can we know about stingrays?

A．They hardly feed on insects.

B．They have a big ball-like fat bod.

C．Their barbed tails serve as a defence.

D．Their body colors vary with the environment.

【小题2】What is the ampullae of Lorenzini used for?

A．Hunting prey.	B．Frightening prey.
C．Protecting sensory organs.	D．Producing a bioelectric field.

【小题3】Why is Irwin's death mentioned in Paragraph 3?

A．To explain jellyfish stings cause death.

B．To show it was an occasional accident.

C．To prove photographing undersea is risky.

D．To stress stingrays are ocean's deadliest.

【小题4】What does the last paragraph mainly focus on?

A．Stingrays' ability to detect magnetic fields.

B．The popularity of wind and wave energy.

C．Stingrays' feeding and migration patterns.

D．The technological impact. on stingrays' life.