Biggest sea creature ever existed
No, thereu2019s no such thing.
They didnu2019t catch on because of their limited usefulness.
,Ekranoplans are, surprisingly, very efficient and stable aircraft once riding on their slim cushions of air.
That is the only advantage they have.
,Their disadvantages were (among others) that they were of very limited wartime use:,They were very slow and hard to maneuver until airborne,They were an easy target for ships, aircraft and missiles,They were hardly quiet or stealthy,Russia had no enemies they could attack using these aircraft with the right combination of a smooth sea approach and the correct range.
,That said, they could certainly have civilian uses and could compete quite handily with traditional jet cargo airliners.
Modern materials and flight control systems could do a lot to improve the efficiency of WIGE aircraft.
The reportedly rough ride would make them less suited for long distance passenger use though.
Also, if you imagine a transatlantic crossing, you cannot predict the conditions at your destination when you depart if it is more than a few hours away.
Ancient sea creatures fossils
This was sold by a Sydney University as part of a fund-raising initiative.
They were being sold individually but I was so fascinated by them, I bought the lot as well as the fossil tray they were placed in.
,They look like dinosaur eggs, but are in fact the fossilised remains of ancient sea creatures, recovered from the Australian desert, dated to over 400 million years ago.
,This is what the earth looked like 400 million years ago when these creatures were alive and where Australia would have been on the giant continent known as Gondwana.
There never were any sea dinosaurs.
Any picture youu2019ve ever seen sof somethimg dinosaur-like in the sea was a marine reptile.
,Marine reptiles (image source: ).
Many marine reptiles survived from dinosaur times, including turtles and crocodiles.
Extinct deep sea creatures
Insects rely on a totally diffusion-based oxygen delivery system, with little to no active transport of oxygen into their bodies.
Their size is implicitly limited by natural oxygen flux.
Decreasing oxygen concentration necessarily implies that their body diameter would have to be reduced if they were already at the maximum, because the effective zero of oxygen concentration occurs at lower penetration depth.
,In contrast, the large sea creatures you are talking about all have some form of forced mass transfer, either through gills (forcing water past what amounts to a mass exchanger) or through air-breathing lungs (forcing air into an efficient mass exchanger organ).
This is exactly the same principle used by all higher animals.
Fundamentally, the answer to your question is thus the same as the answer to why animals larger than giant insects can exist period, in the water or out.
,This is one of my favorites, found commonly in my area.
The name is Halysites, popularly called u201cchain coralu201d (guess why).
Fossil corals go back to the early Paleozoic.