Sea Sawjaws of Meridia

290 Million Years Post-Establishment

The slivertooth is a species of specialized marine sawjaw native to the Meridian Seamount. A more primitive offshoot of the seasaw lineage, slivertooths are smaller animals but belong to a slightly larger genus which shows an intermediate morphology - they are still capable of coming on land, and they are generally coastal.  Their forearms are very well-developed like their relative, but they are less streamlined; the tail is also more visibly jointed and so movement is not fast. The several species of sea-sawjaw in this genus have thus had to adapt alternative methods of finding food that don't depend on high speed.

Unlike true seasaws, which hunt large active prey animals, slivertooths don't need speed to find food, as their foraging style is much more sedate. The lower tooth of this species is very long and unusually shaped in having its tooth cusps angle out to the sides laterally around halfway down its length, causing the lower jaw, rather than the upper, to take on a saw-like shape. They use this immobile tooth to swipe with rapid side to side motions of the head - something that an the moveable upper tooth would not be able to endure, as the way it connects to the skull is only adapted for powerful back and forth motions. Feeding usually occurs in the dense but shallow underwater meadows of the seamount, and involves slashing through the sea grass like a scythe, mowing it down and revealing the hiding places of shoals of benthic fish which it strikes and stuns before swallowing them. The slivertooth more often walks itself through the grass with its claws than truly swims when feeding in this mannner, save for a tail-propelled kick to the surface to breathe every few minutes.

A social animal, slivertooths live in small family clans. Though they may hunt singly, they most often work together to corral fish by cutting the vegetation into a smaller and smaller circle, then attack them when they meet in the middle and have cut out all escape routes. All species in the slivertooth's genus require dry land to haul out onto to rest, and here they gather in large groups on small outcroppings of reefs and scattered tiny islands formed by detritus collected between them. Females especially need these places to give birth and keep their infants in their first few weeks before they are strong swimmers, and in contrast to many animals, the female is up to 30% larger than the male just so she can monopolize the necessary dry land needed by her young. Females sometimes use their larger size to take advantage of additional food sources generally not used by males including larger prey animals that may also gather to rest on land, such as squelicans, especially during child-rearing when they need additional high-energy food sources to provide for their young. Such animals may be caught in ways very different from the normal foraging technique, usually involving the grasping claws on their forearms and a simple bite to the head, showing that the slivertooth - despite its specializations - remains capable of adaptable and varied behavior to suit different conditions.

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The sapphire sawphin is another marine sawjaw native to the shallow seagrass plains of the Meridian seamount, known for its brilliant coloration. A sister species to the much bigger seasaw (the largest sawphin), it is immediately recognizable for its vibrant coloring, a striking mix of deep blue, teal, and yellow flashes of pigment. While seasaws are apex predators, all other species are significantly smaller and generally hunt much littler quarry. Sapphire sawfins are agile, social hunters of schooling shallow water and surface-dwelling fish and snarks, which they capture through closely coordinated sweeping movements through seagrass that flushes their prey up into open water where other individuals swoop down to cut off their escape. Sapphire sawphins have small forearms, as they do not use them to capture prey; they are primarily used to hold onto partners during mating, which occurs face to face. Among the most derived sawjaws, sawphins' bodies are mostly made up of their long tail, which provides their propulsion while swimming; large muscles and thick fat deposits totally obscure the separation of tail and abdomen. Due to their proportions making walking impossible, these animals are unable to move on land, and do not leave the water. Sapphire sawfins are extremely agile and can turn quickly to corner their prey, steering with very large pectoral fins derived directly from the ear pinnae of their terrestrial ancestors, even as no external ear canal remains. But like other marine tribbetheres, the skeletal structure of their tail, which still retains knee and ankle joints now largely hidden beneath its streamlined form, means they are not as fast as fish - their hunting technique, like the seasaw, relies on cooperating to ambush their targets rather than pursuing them at a sprint.

Both sexes of this species are boldly marked and exceedingly beautiful, though males are the brightest of all and are identifiable from females by dark markings around their eyes, which are outlined with bright neon blue whereas in females the skin around the eyes is dark blue all over, as on the rest of the head. These colors are only visible in near-surface waters where sunlight is abundant, and their patterns reflect their habitat specialization to such environments - they very rarely dive deeper than 50 feet and prefer to forage in water less than ten feet in depth, as it gives their prey little height to flee and escape them. Their primary range centers around the Meridian seamount, as their fondness for shallow water keeps them from venturing far off this underwater island; vagrants to distant coastal waters appear every so often, but rarely stay long, possibly as competition for food is greater in regions closer to the continental shelf, not to mention larger predators are found there; unable to hide, and not especially fast, these sawphins are poorly adapted to more competitive ecosystems than they find in their small and relatively isolated range. 

Unlike seasaws, sapphire sawphins have multiple breeding females in a group, and less defined dominance hierarchy in general. Males mate with several females and are active co-parents, often watching newborns as their mothers are hunting, and holding the young near the surface so they can easily breathe. Groups are usually matrilinear and can begin with as few as two females (usually sisters) and a single male, but over time can grow to include many daughters, aunts and grandmothers. Males disperse at maturity, which occurs around five to six years of age, and so avoid mating with close relations. Development is slow, and young learn a lot from their elders as far as how to find food. A single female will only give birth to one young every three years, as even by then her older offspring, though nearing adult size, will not be wholly independent for two more years. Sawphins are a recently diverged clade, and sapphire sawphins are very closely related to several other species in their genus which are more wide-ranging, some of which are only a million years apart, possibly less, despite often showing very different color patterns (which have evolved to facilitate instant recognition of like-kinds.) Where they coexist, hybridization still occurs at low frequency, though cross-fertility is limited, and usually only males are fertile. Among sawphins, only the seasaw is generally too divergent in size and behavior to mingle in this way with its relatives - it is far more likely to eat them where they meet.