240 MYH Southern Ocean. The seaway between the South Pole and the Coastal Lowlands is the most productive part of the ocean. Upwellings of cold water from the southern ice sheet and nutrients from the coast create vast blooms of algae and krill.
Filter-feeding Ichthyichty and Kitefin Sharks are found in their largest numbers here along with many Seabird-Blish and smaller marine animals following in their wake.
The shoals of baitfish attract Arctic Squeal (Phocateuthis communis) the most common members of a clade of semi-aquatic descendants of the Marsh Mouth of 10 million years ago.
Reduced eye stalks and strong back legs that serve as tails allow them fast movements to chase after fish and squid with conical tentacle teeth.
At this time of year, they gouge themselves on the winter bounty before spring when they return to land to breed, and many take advantage of the floating mats of vegetation washed out to sea by the winter rains that attract large shoals of fish.
As one chases a group of Epipelagic lanternfish through the vegetation the plants shift as a massive serpent lunges out of the grass startling the Squeal back as the Serpentine Lungestrike (Marepercussor absconditus) displays its rows of crushing odontode tooth plates.
Fortunately, the giant marine Lungfish hunts smaller prey than the Squeal, things that can be eaten in a few bites, and its serpentine body makes it a poor swimmer and vulnerable in open water so it doesn't leave the safety of the floating vegetation.
The Lungestrike is more annoyed that its low-energy torpor was disturbed as it can go for long periods without eating in its ocean migrations via floating vegetation.
These two are some of the unique wildlife of the world's oceans