Evolutionary Escalation In Squids and Whales

How do you find squid in the dark depths if you are a toothed whale or dolphin? Lindberg an expert on molluscs and Pyenson an expert on whale evolution propose that ecolocation in the ondontocetes, or toothed whales, arose as mechanism to locate squid buffets. To view this story we need to go back, way back.
45 million years ago the land mammals entered freshwater and evolved the necessary equipment to survive in an aqueous medium except obviously the ability to breath underwater. These first whales did not echolocate, which is known because their foreheads were not scooped to allow for “a fatty melon-shaped ball thought to act as a lens to focus clicking noises.” About 8 million years later you get dented foreheads in the whales about the same time they move into the ocean.


But what were the intermediate steps? “Lindberg and Pyenson propose that whales first found it possible to track [hard shelled cephalopods] in surface waters at night by bouncing sounds off of them, an advantage over whales that relied only on moonlight or starlight.” Thus when squid migrated into the depths over the course of day, whales could follow and forage. But then 10 million years ago, nautilus tired of losing all there nautiloid brethren moved from the open ocean to protected reefs. “Lindberg said that the decline in nautiloid diversity would have forced whales to perfect their sonar to hunt soft-bodied, migrating squid, such as the Teuthida, which in the open ocean are typically two feet long or bigger and range up to the 40-foot-long giant squid.”

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Dr. M (1729 Posts)

Craig McClain is the Assistant Director of Science for the National Evolutionary Synthesis Center, a National Science Foundation supported initiative. He has conducted deep-sea research for 20 years and published over 50 papers in the area. He has participated in and led dozens of oceanographic expeditions taken him to the Antarctic and the most remote regions of the Pacific and Atlantic. Craig’s research focuses on how energy drives the biology of marine invertebrates from individuals to ecosystems, specifically, seeking to uncover how organisms are adapted to different levels of carbon availability, i.e. food, and how this determines the kinds and number of species in different parts of the oceans. Craig’s research has been featured on National Public Radio, Discovery Channel, Fox News, National Geographic and ABC News. In addition to his scientific research, Craig also advocates the need for scientists to connect with the public and is the founder and chief editor of the acclaimed Deep-Sea News (http://deepseanews.com/), a popular ocean-themed blog that has won numerous awards. His writing has been featured in Cosmos, Science Illustrated, American Scientist, Wired, Mental Floss, and the Open Lab: The Best Science Writing on the Web. His forthcoming book, Science of the South (http://www.scienceofthesouth.com/), connects cultural icons of South such as pecan pie with the science behind them.

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