考研英语阅读篇章深海潜水能手智利魔鬼鱼_大学英语阅读

考研英语阅读篇章深海潜水能手智利魔鬼鱼

　　The deep dives generally followed two distinct patterns. The most common involved descent to the maximum depth followed by a slower, stepwise return to the surface with a total dive time of 60 to 90 minutes. The tagged rays generally only made one such dive during a 24-hour period. In the second dive pattern, individuals descended and then remained at depths of up to 1,000 meters for as long as 11 hours.

　　During the day, the rays would spend time up at the surface -- presumably heating up -- immediately before, and then again, after a deep dive. How else might these animals be dealing with the cold temperatures of the deep ocean?

　　A previous study in the 1970s found that several species of devil rays possess a physiological adaptation -- well-developed blood vessels around the cranial cavity that essentially serve as heat exchange systems. At the time, it was hypothesized that the rays must be using this adaptation to cool down rather than warm up.

　　Rays were always seen in very warm water up at the surface, so why would they need an adaptation for cold water? Once we looked at the dive data from the tags, of course it made perfect sense that the rays have these systems. Sometimes they re down diving for two or three hours in very cold water -- two to three degrees Celsius , Thorrold said.