Eelamanders

Eelsnakes are a truly ancient lineage which arose very early on Serina. Initially, this group was a major innovation: one of the first ray-finned fishes to adapt to live at least part-time on land. These swordtails did so in a very different way from the guppy-descended tribbits, and they became elongated animals which both swam in an undulating manner and slithered over the ground on their bellies, thus their names. As Serina became an older world, and many animals around them became virtually unrecognizable, the eelsnakes remained little changed. Their niche worked well, and few had reason to try new shapes. By the ice age, the massive river dragon was the most charismatic species, and in the hothouse that followed its descendants remained among the most successful and certainly most visible in most habitats. But the river dragon (turned sea dragon) wasn't alone among the eelsnakes in surviving the great thaw. Initially all but hidden from sight, scrounging in leaf litter and mud in that icy wasteland, was the extraordinarily cold-hardy firebellied fangworm. 

When the world warmed suddenly at the start of the hothouse, fangworms were ironically not well-adapted to take advantage. They were so well adapted to the boreal climate that they were now prone to overheat, and for the most part, they immediately sought refuge in cooler underground environments throughout the start of this period, becoming cryptic and very little seen. Only now, ten million years later, have a few representatives of this lineage begun to trickle back out of the dark and experiment in new ways of life in a dramatically altered world. One of the easiest ways for a burrowing animal to venture out from its familiar habitat is to enter the water - it often floods below ground, especially in this climate, and the same movements are usually useful both to move in tunnels and to swim through the water. So it is not too surprising that the first large, non-fossorial fangworms of the hothouse became sea creatures - secondarily so, after hundreds of millions of years, just as the sea dragons did. 

The marine fangworms are now known as eelamanders. These descendants of the strikeneck fangworm retain a simple, serpentine shape; the only major differences from their ice age ancestors is the quick adaptation of a paddle-like tail, a lack of differentiated "fingers" on their pelvic fins, and an unusually elongated "neck", with many vertebrae sitting between these fins and the skull. The neck of the eelamanders evolved in their burrowing ancestor, perhaps benefiting it as it hunted small prey in narrow tunnels. Now it makes up almost a third of the body length - when it is extended, at least. This neck is remarkable for its ability to contract by nearly half its length when necessary, improving its swimming speed, as the vertebrae are connected by stretchy ligaments, and there are no organs in this portion of the body. Then, as the animal feeds - usually in rocky reef areas - the neck elongates and strikes down into narrow crevices, mainly in pursuit of small fish. Like land fangworms, eelamanders remain highly venomous, relying on the potency of their bite to paralyze their prey immediately and so prevent it from escaping out of reach deeper into the reef after being bitten.

Like some sea dragons, female eelamanders are excellent parents. Up to twenty-five young are born alive in a litter, and instinctively shoal tightly against each other and their mother. She defends them from predators, her own varied, often garishly colorful markings advertising her deadly bite. Though the adult of each eelamander species has its own distinct pattern, nearly all of the babies resemble each other with black and white bands, a sort of disruptive camouflage that blends them all together into one indiscernible shape as they school together, keeping predators from singling one out of the group. Young remain with their mother for around two months, until their stripes fade and adult colors develop along with their venom. Until that time, they rely on their mother for food, which is provided indirectly in the form of small flesh chunks tossed off her own kills as she shakes them around in her jaws to dismember them into pieces small enough for herself to gobble up.