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February 7 Information

Cetacean dorsal fins

It is well known that land vertebrates' limbs evolved from fins, and in cetaceans they became fins (flippers) again. But what about dorsal fins? Is their fetal development in whales and dolphins controlled by the same genes as in fish? Meaning, when they evolved, did long dormant genes reactivate, or is it a completely new development? If it's not known on a genetical level, are they similar structures anatomically or are there fundamental differences? User38453838 ( talk) 07:21, 7 February 2020 (UTC) reply

They seem to be a new development: "There aren’t any bones or cartilage in the dorsal fin and flukes. Instead, they’re made up of dense connective tissue" in https://oceantoday.noaa.gov/killerwhaleanatomy/ 2003:F5:6F06:7900:D570:A85B:2650:24B6 ( talk) 11:12, 7 February 2020 (UTC) MPB reply
Note that the gray whale lacks a dorsal fin: "instead bearing 6 to 12 dorsal crenulations ("knuckles"), which are raised bumps on the midline of its rear quarter, leading to the flukes. This is known as the dorsal ridge". Alansplodge ( talk) 17:40, 7 February 2020 (UTC) reply
From Wikipedia, the free encyclopedia
Science desk
< February 6 << Jan | February | Mar >> February 8 >
Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is a transcluded archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.


February 7 Information

Cetacean dorsal fins

It is well known that land vertebrates' limbs evolved from fins, and in cetaceans they became fins (flippers) again. But what about dorsal fins? Is their fetal development in whales and dolphins controlled by the same genes as in fish? Meaning, when they evolved, did long dormant genes reactivate, or is it a completely new development? If it's not known on a genetical level, are they similar structures anatomically or are there fundamental differences? User38453838 ( talk) 07:21, 7 February 2020 (UTC) reply

They seem to be a new development: "There aren’t any bones or cartilage in the dorsal fin and flukes. Instead, they’re made up of dense connective tissue" in https://oceantoday.noaa.gov/killerwhaleanatomy/ 2003:F5:6F06:7900:D570:A85B:2650:24B6 ( talk) 11:12, 7 February 2020 (UTC) MPB reply
Note that the gray whale lacks a dorsal fin: "instead bearing 6 to 12 dorsal crenulations ("knuckles"), which are raised bumps on the midline of its rear quarter, leading to the flukes. This is known as the dorsal ridge". Alansplodge ( talk) 17:40, 7 February 2020 (UTC) reply

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