Below is an instruction that describes a task. Write a response that appropriately completes the request in Chinese. Please answer in Chinese.

### Instruction:
 为了吃饱牡蛎，螃蟹必须至少吃掉乌贼的两倍牡蛎。如果乌贼吃了200只牡蛎，他们总共吃了多少只牡蛎？


### Response:
 当乌贼吃了200只牡蛎时，螃蟹吃掉乌贼的两倍牡蛎，他吃了2*200 = 400只牡蛎。
他们总共吃了400+200= <<400+200=600>>600只牡蛎。