56
votes
Accepted
A fast aquatic predator with multiple eyes and pupils. Would these eyes be possible?
This is the four-eyed fish:
It has only two eyes, but it has two pupils and two retinas in each eye. It evolved to hunt by the water surface, catching prey from both above and below.
Where there is ...
- 142k
47
votes
Accepted
Could a jellyfish be bio-engineered to convert salt water into fresh water?
No. Jellyfish are osmoconformers
Osmoconformers are marine organisms that maintain an internal
environment that is osmotic to their external environment.[1] This
means that the osmotic ...
- 305k
46
votes
Accepted
What if the ocean's salt level decreased by 50%?
Phase 1: The Extinction
Most life in the sea would die out almost immediately. Saltwater fish, invertebrates, and most importantly plants and microbes are finely-tuned for a particular level of ...
- 29.1k
45
votes
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Living biological boats? (Jasconius)
That's where its food source is.
Most algae is found near the surface of the ocean, so if this creature has a semi long neck, it can swim gently along moving its head back and forth, up and down ...
- 7,191
42
votes
Accepted
Would the existence of Megalodon during the medieval ages threaten Sea Travel and how to defend against them?
No
Megaladon is not fundamentally a more fearsome or ferocious beast than a sperm whale, which is also carnivorous, of similar size, probably smarter, and has as documented capability to sink 240 ton ...
- 85.7k
40
votes
How would a ship defend against a sea creature, and possibly win?
Rolling attack - Have a heavy keel
I just wrote a big post about naval architecture principles, much of which applies here as well. To minimize the chance your ship rolls, attach a heavy keep to the ...
- 85.7k
39
votes
Would oceans filled with long-lived, omnivore, intelligent Krakens make sea travel impossible?
Octopi play.
source
The ocean can be terrifying. More terrifying is being played with by an intelligent predator. It grabs a person then leaves. It hits the boat and then leaves. It throws a huge ...
- 305k
35
votes
Why would a species that had never been exposed to light react to light?
Because it can still feel temperature differences.
Light is energy. Depositing energy on the skin (or deeper in the body, if the skin is transparent, as it often is for deep sea creatures that live in ...
- 42.4k
30
votes
Living biological boats? (Jasconius)
Needs sunlight
It could have a usage for sunlight. Maybe a system similar to how plants use sunlight in photosynthesis. Heck, it could be exactly that. Make it have cells with photosynthetic ...
- 883
30
votes
Accepted
Would merfolk gain any real advantage from mounts (and beasts of burden)?
Yes, they would.
I can affirm this because mounts follow the general yet extremely potent principle of specialization : A specialized entity -person, machine or animal- will always perform better than ...
- 7,517
26
votes
Accepted
How long could a Kraken's carcass survive if preserved in salt?
I'm going to assume that when you say "Kraken" you mean "giant octopus monster" meaning something biochemically identical to a modern octopus but huge. I'm also assuming that the water stays gone and ...
- 49.4k
26
votes
Hammering under water?
That would be not a hammer, but an axe.
Stone age hammers and axes did not differ much, and in most cases were both - depending on the side you used (this is still the case for "civil" axes). An axe ...
- 9,923
22
votes
Would oceans filled with long-lived, omnivore, intelligent Krakens make sea travel impossible?
I am not sure that those kraken would consider human ships interesting prey. After all most of the ship is inedible (wood) and hunting those little, pesky critters hugging to the "huge log" ...
- 2,301
20
votes
Accepted
What underwater creature would be well-suited as a pack animal?
You're going to want to obtain some whales. Not only are they the largest mammals alive, they also have the largest muscles.
Whales travel in pods, the equivalent of a "pack" of wolves. They're ...
- 19k
20
votes
Why would modern humans not use scuba gear for missions underwater? (But freedive instead)
Stealth
Man-made materials like metals, plastics, and ceramics have very distinct qualities that allows Sirens to immediately identify submarines and scuba gear from miles away. It's so distinct if ...
- 101k
19
votes
Sonar Jamming Squids
A cloud of smaller host creatures scatters the sonar.
The squid is followed by a cloud of small creatures that scavenge the scraps of the squid's food. In return they serve to scatter the sonar waves ...
- 66.2k
18
votes
What if the ocean's salt level decreased by 50%?
Life would not be able to evolve in this short amount of time. Organisms able to survive the lower salt concentrations (of which there would be some in the ocean) would survive, organisms not able to ...
- 4,848
18
votes
How would a ship defend against a sea creature, and possibly win?
If your kraken is basically like a giant squid, we can take a two-pronged approach to defend against all of your attack methods.
First we want to prevent the kraken from grabbing hold of your ship to ...
- 3,032
18
votes
Accepted
Could a mature (and giant) lobster remain in sea water indefinitely without decaying?
What would she look like after a few hundred years of submersion?
Like a really big lobster. Regular lobsters live in the sea, and can live to over 100 years old and still look just like lobsters. ...
- 78.4k
16
votes
Living biological boats? (Jasconius)
Buoyancy is a big deal for sea creatures. Pretty much everything living on or in water have a density that makes them naturally comfortable (i.e. energy efficient) only at certain depths, and changing ...
- 493
16
votes
Under what circumstances would a nuclear war render Earth's oceans uninhabitable?
Not possible. You land dwellers need the ocean to survive.
Don't forget that the oceans are part of the water cycle. If they are so messed up from radiation that no life can thrive in them, then the ...
- 142k
16
votes
What is Plausibility of a Megalodon sized creature attacking a human?
Because Humans in the water are really easy to eat
As a general rule in all manner of combat/hunting/dogfights/racing: Smaller and lighter = more agile.
For a predator, there is a point at which it's ...
- 32.4k
15
votes
Accepted
How to let a Whale urh... fly?
Note that whales have no wings, so they cannot fly like a bird or a bat; they would have to fly like a balloon or Zeppelin. Basically, you need to get their density down to less than the density of ...
- 31.5k
15
votes
Sonar Jamming Squids
I've a few thoughts:
Similar to the use of specific geometry and materials in stealth aircraft and watercraft to foozle radar, one could envision a very bright colossal squid draping itself with ...
- 5,811
15
votes
Plausibility of squid whales
https://www.livescience.com/54870-giant-squid-may-be-school-bus-size.html suggests that existing giant squid could reach 20 meters in length. Given a lack of whales and the biological variations you'...
- 1,029
15
votes
How would thermophilic fish survive?
There are a lot of such organisms right here on Earth. Undersea volcanic activity produces hydro-thermal vents. These are places where water is heated and then rises out of the sea floor. Typically ...
- 9,591
15
votes
Accepted
How does the kraken get its bait?
Stuff it ate earlier.
https://www.youtube.com/watch?v=14wWxaMR2Mg
Here an orca has regurgitated a fish for use in baiting birds. I watched one do this probably at this exact spot. In my video, when ...
- 305k
14
votes
Accepted
A Freshwater Octopus?
Picture a lake directly connected to the Ocean or rather an inland sea. It has some flow of fresh water into it from rivers, but it's large and because of it's connection to the Ocean the salt ...
- 11.4k
14
votes
A Freshwater Octopus?
Cephalopods don't have a sodium pump in their gills in the way arthropods and fish do. Their "kidney"(nephridium) handles all osmotic balancing, which is fine in the ocean but makes it nearly ...
- 81.9k
Only top scored, non community-wiki answers of a minimum length are eligible