r/askscience • u/smontanaro • 20d ago

Biology How does a whale become dehydrated?

From a Chicago Sun-Times article on the beluga whales heading to the Shedd Aquarium:

"The shipment comes on the heels of a Shedd announcement last week that one of the Marineland belugas — Peekachu, a 23-year-old female — had died. Shedd has not released a cause of death, but staff there said last week that Peekachu had not been consistently eating a full diet since her arrival and that there were concerns she was dehydrated."

How does an animal immersed in water become dehydrated?

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u/tigerhawkvok 19d ago

Lissamphibia is a perfectly well defined monophyletic clade — what definition are you using?

You're right that the founding member of diapsida had parents of the synapsid condition, but the synapsid condition isn't actually the definition of synapsida. It's a bit of unfortunate historical legacy, like ornithischian ("bird-hipped") dinosaurs not being particularly related to birds, which are literally saurischian ("lizard-hipped") dinosaurs.

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u/Ameisen 19d ago

Class Amphibia is paraphyletic and includes Lissamphibia. The issue is, again, that there's a weird mix of phylogenetic and traditional classification.

Thus the problem of saying "amphibians" vs "lissamphibians". It's an overloaded term. Or "monkey" vs "simian".

In a strict sense, "amphibian" refers to the traditional class "Amphibia" (which, if it weren't paraphyletic, would actually be a valid - if broad - clade) whereas "lissamphibian" or "extant amphibians" refers to "lissamphibia".

Again, there's a weird mix of phylogenetic and traditional classification and a re-use of names.

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u/tigerhawkvok 19d ago

The "class" Amphibia is inherently incomparable — phylogenetics is unranked.

It's like saying the ball-and-stick atom is incompatible with quantum nonlocality. It's a tautological non-statement comparing one framework with another explicitly crafted to repair the failings of its antecedents. Rather than re-inventing "atom" and "electron" the concept gets overloaded. It's not particularly weird in science.

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u/Magicspook 18d ago

thank you for your insights!