Fish out of Water: Mudwickets and Eelsnakes

Mudwickets, a group of semi-terrestrial guppies that first appeared about 25 million years ago, have diversified enormously since the middle Tempuscenic, despite a cooling climate. Found across the subtropical belt in Serina's east, where Striata meets Whalteria, these formerly water-bound fishes have begun to totally cut their ties to the water. Many mudwickets now live entirely on land, in the soggy leaf litter of forests and jungles or in deep burrows in drier environments. Their pectoral fins have become well suited to digging, with five exceptionally large claw-like rays. So long as they can keep moist, they needn't ever actually submerge in water anymore and oxygen is absorbed through all of their skin right out of the air, including that of the gill membranes, but particularly the mouth, which is brilliantly red with oxygenating tissue. As guppies the mudwickets breed internally, with the male using the gonopodium fin located under his tail to transfer sperm directly into the female's body and to her ovaries, negating totally the need for water even to breed, as amphibians require. The young can move on land from infancy and are usually born in burrows. Some species are protected by the parents for a short time after birth until they leave to begin hunting on their own.

Two angry male mudwickets argue over territory.

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Mudwickets are strange looking animals, with bulbous eyes, often wide grinning mouths, and colorful dorsal fins on their backs. Their jaws are extendable and full of needle-sharp teeth, for they are all carnivores, and males in particular are aggressive and showy creatures, battling over territory and flaring fins and brightly colored jaws and gill covers to intimidate one another and attract the attention of smaller females. Tough though they are in demeanor, they are squat and chubby creatures and ungainly at best in locomotion, and their battles often involve nothing more than pushing against one another until one or both roll over. They can pull themselves along with their clawed pectoral fins underground, while above ground they rely on thrusts of their squat but still well-muscled tails to produce short hops. The tail now lacks a fin and is specialized to the task of propulsion over land, curving to the side and ending in a flattened pad of rough scales to get traction on the ground. Mudwickets may be either right-tailed, with their tail twisting to the right, or left-tailed, and this determines which way the most effectively jump - though neither is particularly good at aiming for an exact perch. Most species spend most of their time underground, feeding on small worms, grubs, and other such beasties, and rarely move around over land during the day, preferring to do so in the dark when their avian predators are less active. Unfortunately, one group of animals which has recently appeared on the world of birds doesn't share the same preferences of time to hunt. Slithering quietly out of forest pools and streams with a side to side slinking motion through the moss and liverworts, the eelsnake searches for food.

Eelsnakes are elongated eel-shaped swordtail fishes, one to two feet in length, which have evolved to hunt on land as well as in the water. Taking in atmospheric oxygen via a lung-like bladder budding off their stomachs, they too can stay out of water indefinitely as long as they stay relatively moist. Spending the day resting at the bottom of pools, tangled in vegetation and occasionally striking out at some small pasing prey item, they do most of their hunting on land. Traveling by night when the ground is moist with dew does the trick to ensure they don't get too dry while they're at it, as the hunters emerge in groups from the water like shimmering rubber ropes and quickly disappear into the undergrowth. They shuffle their heads around this way and that, showing off an exceptionally mobile neck for a fish. They press their snouts deep into the mud and inhale every few feet, sniffing around in search of their preferred prey; earthworms, slugs... and mudwickets. Their eyes which work well underwater are a bit blurry on land, but the eelsnake has an excellent sense of smell, heightened by a pair of short barbels that carry scent particles right up to the nostrils from the ground, and it can easily follow the scents of the small creatures it hungers for deep down underground by merit of its flexible, sinuous body.

An eelsnake slithers over a forest floor in search of food.

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When the eelsnake finds something in the burrow, it strikes quickly and aggressively, wrapping its highly elastic jaws around the prey and positioning it via its long, backwards-curved teeth into a position to be swallowed whole, headfirst for vertebrate prey. The mudwicket may struggle, inflating its body with air and thrashing with its claws, but it's no use. Unable to cry out without vocal cords, the only sound it can make as its tail slips down the hungry hunter's gullet is the faint squeak of the air it just inhaled being compressed out of its body. It may struggle for a while in the eelsnake's stomach, while it turns around in the burrow and makes its way - a little more slowly - back to its pool to digest. Eventually without oxygen in the predator's stomach, the prey is suffocated and the eelsnake slides back into the water, making its way back to a cozy tangle of water weeds to rest. A large meal can satiate it for a week, but before long it will be back on the shore, in search of another course.

Originally most mudwickets were quite defenseless to predators such as the eelsnake, relying on camouflage and the safety of their burrows alone to avoid predation - and still often being taken by birds and other animals... until some developed a new line of defense. Poison, concentrated in their skin and scales from a diet of the noxious ants and other insects that are so numerous in Serina's forests, proved a successful deterrent to predators. An eelsnake that bit into a neurotoxic mudwicket wouldn't get a chance to try to do so again... but neither would the mudwicket, already swallowed down the predator's gullet. To the protection of both parties involved, one group of highly toxic mudwickets armed itself with vibrant warning coloration, bold and contrasting splotches of blue, yellow, black and red, biological signs yelling loudly and clearly "I am deadly!". The "poison dart" mudwickets were born. Just like their frog analogues in the rainforest back on Earth, predators steer far clear of any squat little creature hopping unperturbed on the forest floor while wearing the cloak of colored death. Some of the brightly colored mudwickets, no longer having predators to fear, have become diurnal. Others have lost many of their burrowing adaptations, no longer needing to hide to survive. And hitching a ride on the band wagon, a fair few harmless mudwickets, with completely innocuous diets, have developed mimicry of their poisonous kin to avoid predators without actually being toxic at all.

A brightly colored mudwicket, made toxic by a diet of poisonous ants, advertises its unpalatablility.