Re: Why can’t marine animals survive in fresh water?


Marine vertebrates which were in their past terrestrial, often move back and forth between marine and fresh water. Both in extant and fossil populations. 

On Thu, Sep 22, 2022 at 5:54 AM Marc Verhaegen <m_verhaegen@...> wrote:
Why can’t marine animals survive in fresh water?
Helen Scales 2022

If  you plopped a marine fish in fresh water, it would start absorbing
lots  of water across its gills. It wouldn’t take long for it to get
into  trouble with the balance of water & salt in its body.
It might even  swell up!
Their bodies are more salty than fresh  water, so they absorb water via
Freshwater fish face this same  problem, but they’re adapted to get rid
of water quickly – mainly by  peeing a lot.
Some fish (eels, salmon,)move between sea & fresh water by altering
their biology, but it takes a lot of energy & time to switch from sea &
freshwater living.


H.erectus = salt water: pachy-osteo-sclerosis++.
H.neand. (less POS) was more riverside?  seasonally following the

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