Great photo selection with the shifty looking seal (gotta love the whites of caniform eyes) and a nice little summary of the article.
One thing about zoology and animal morphology is that we all know how important feeding is for animals but only real nerds love the digestive tract. Transport, skin, and reproduction are far more glamorous; but the mammalian sense of smell and mouth parts gave us such an advantage in the tertiary period.
It’s interesting that this sort of feeding never arose in the sea. I wonder what the ancestors of the pinnipeds who first ventured back into water ate…
If you find this evolutionary history interesting then I can't recommend PBS Eons enough. It's a great youtube series on the subject: well researched, a dense but breezy pace, and the paleo art + fossil images help convey information without being overly dry.
"Pinnipeds evolved about thirty million years ago. They showed up first in the colder parts of the northern hemisphere, then in the Antarctic, then in temperate zones."
That's an interesting sequence, given that the continents then were about where they are now.
Maybe they evolved in both places independently, or maybe it took a couple million years for a pod of seals to make the journey from north to south, and then start dominating the local ecosystem.
Wikipedia says pinnipeds are monophyletic, so there's only a single evolutionary branch they originated from.
The travel question is much more interesting. Napkin math puts the distance between the polar circles at 12500 miles, the max swim speed of a seal at 25mph, giving a travel time of ~3 weeks of nonstop swimming as the crow flies. How does that happen? What would a pod of Arctic seals have eaten along the way, and what would have compelled them to make the trip out of familiar territory? How and why did they cross the temperate equatorial seas with a load of blubber?
That is interesting. I looked it up on wikipedia and the Argonaut / Paper Nautilus "shell" is a thin walled eggcase and that males do not have. It does not provide protection.
Female argonauts have the shell their whole life long, and do not only construct it when they have eggs to put in it. We may reasonably assume that it has survival value even when there are no eggs. We know, for example, that they carry bubbles in it to tune their buoyancy.
> If you’re inclined to be pedantic about the nautilus’ limbs and say that /actually/ they are “arms” and not “tentacles” because tentacles have suckers on them, then (a) congratulations on remembering that long-ago biology class, and (b) see Footnote 1, above.
Something tells me an arm is a mechanical limb composed of connected poles that turn at their joints. And a hose-like limb without suckers should have its own name. A foot is an "arm", a penis is something else.
Readit News
One thing about zoology and animal morphology is that we all know how important feeding is for animals but only real nerds love the digestive tract. Transport, skin, and reproduction are far more glamorous; but the mammalian sense of smell and mouth parts gave us such an advantage in the tertiary period.
It’s interesting that this sort of feeding never arose in the sea. I wonder what the ancestors of the pinnipeds who first ventured back into water ate…
Here's the one about this subject: https://www.youtube.com/watch?v=3vQ55ToQeWI
That's an interesting sequence, given that the continents then were about where they are now.
The travel question is much more interesting. Napkin math puts the distance between the polar circles at 12500 miles, the max swim speed of a seal at 25mph, giving a travel time of ~3 weeks of nonstop swimming as the crow flies. How does that happen? What would a pod of Arctic seals have eaten along the way, and what would have compelled them to make the trip out of familiar territory? How and why did they cross the temperate equatorial seas with a load of blubber?
https://www.sciencefriday.com/articles/the-seamstress-and-th...
https://www.themarginalian.org/2022/12/26/jeanne-villepreux-...
Jeanne Villepreux-Power invented marine biology, single-handed in the early 19th century.
She observed them repairing a hole in their shell by gluing on a found patch.
This one did though: https://crookedtimber.org/author/doug-muir/
Something tells me an arm is a mechanical limb composed of connected poles that turn at their joints. And a hose-like limb without suckers should have its own name. A foot is an "arm", a penis is something else.
about Voyager 1, recently in the news
Evolution is amazing innit.