A、Some sea creatures developed backbones. B、The first giant squid was captured. C、Some sea creatures shed their shells. D、Sea li

M: I really appreciate your filling me in on yesterday’s lecture.
W: No problem: I thought you might want to go over it together. As anyway, It helps me review. Hope you’re feeling better now.
M: I am. Thanks. So, you said she talked about squid? Sounds a little strange.
W: Well, actually, it was about the evolution of sea life --a continuation from last week. The octopus and the squid descended from earlier creatures with shells. They survived by shading the shells, somewhere between 200 and 500 million years ago.
M: That’s a pretty long span of time.
W: I know. That’s what she said, though. To be precise: "Exactly when they emerged is uncertain ... and why is still unexplained."
M: Some squid are really huge. Can you imagine something that big if it still had a shell?
W: Actually, it’s because they lost their shells that they could evolve to a bigger size.
M: Make sense. But some are really huge. I’ve read about fishermen that caught squid that weighed over a ton. Did she talk about how that happens?
W: Not really. But she did mention some unusual cases. In 1933 in New Zealand they caught a squid ... let’s see here ... it was twenty-two yards long. Its eyes were eighteen inches across. Can you imagine?
M: Reminds me of all those stories of sea monsters.
W: Dr. Simpson thinks there are probably even larger ones that have been found, because squid are intelligent and fast-- so they can easily get away from humans. Maybe some of those monster stories are true.