NOTE - EVERYTHING BELOW HERE IS A SPOILER FOR SEA WATCH - YOU HAVE BEEN WARNED
The Sea-kinden in the Ocean between the Lowlands and the Spiderlands have organised themselves into Seven Families of kinden.These appear to be treated as a form of caste structure, with 2 great families, 1 sort of middle class and 4 lesser families. Possibly due to the nature of their environment, many more sea-kinden develop the art to communicate, empathically or telepathically, with the creatures of their totem. It isn't unusual for a sea-kinden to be strongly linked with a specific beast that they would consider 'theirs'.
We don't know whether the families cover every possible invertebrate kinden in the oceans, and there are a couple of possibilities that could be quite odd. Barnacles are often thought as more like shellfish, but would be more closely related to the Onychoi than Gastroi. Then again, if you were to call a barnacle-kinden an Onychoi, then woodlouse-kinden would technically be part of the family as well.
As well as the families of kinden, the sea-dwellers are split into different paths, based on how they survive in the ocean depths. Five of the families are split between the three main paths, to a greater or lesser extent, with two being exceptions in their own way. The main paths that are followed are
The Archetoi are linked strongly to the Obligists, but separate from them.
The Echinoi are entirely departed from civilisation, swarming with their beasts in a destructive manner and being the only sea-kinden to have no use for air.
That said, not everyone stays on the same path all their life or even follows one of the paths, and there appears to be a new one developing for those who make use of artifice to live.
Then again, there is another group, the Littoralists. These appear to be more of a belief structure or religion and one could be a follower of any path and a Littoralist at the same time.