(( I figure I should get the details of how I see the seadweller traits in my head posted. Most of this is pretty dull but I think it’s worth clarifying.
Gills are situated on the torso, sitting slightly below the breast region, on either side of the chest. They’re a definite weak point for any opportunistic attackers, but damage will only impede breathing when underwater; regular lungs are used to breath air. When the gills are being actively used to breathe water, the passageway to the lungs closes off, so seadwellers can inhale water without drowning. The gills can draw in oxygen from the water through fabric without being too heavily impeded, so clothing isn’t a huge issue.
Situated where ears would be on a normal troll, perform similar functions but are more inclined towards orienting oneself when underwater, like ears are used for balance in humans. They still function for that purpose, too, however. They tend to flare/twitch when a seadweller is enraged or surprised.
Shark teeth. Fuck yeah. Basically the teeth you see on a great white shark, except at a size more appropriate for troll mouths.
They’re fucking sharp, and don’t require a huge amount of pressure to make a cut. They don’t grow in rows like they do in sharks, but much like other trolls, teeth can regrow, so breakages aren’t a long term issue. Unlike sharks, the teeth are actually attached to the jawbones directly, instead of being attached purely by the gum.
Swimming related stuff
Obviously a seadweller’s body is more optimised for swimming than that of a land dweller. Feet are webbed, and the body itself is structured in a way that it can withstand much higher pressures than that of a normal troll, to facilitate delving deep into the ocean when need be.
Water is cold. For this reason, seadweller physiology tends to favour cold temperatures; a seadweller will struggle much more in hot situations than their landbound cousins. Stick a seadweller in the desert and they’ll last a hell of a lot less time than a landdweller.
Seadweller skeletons are made of slightly less dense material than that of land dwellers, similar but not entirely the same as the cartilage skeletons sharks and rays have. It’s more than dense enough to support life on land without too much trouble, but is lighter and slightly more flexible to facilitate better movement underwater, meaning it’s generally easier to break.