Name: Elea Foxfire
Age: 23
Species: Deep Sea Otter
Explanation of species:
The deep sea otter is one of the most intriguing hybrids to be found in the depths, as it has most of the adaptations necessary to not only survive the cold and extreme pressures of the deep, but also to be a surprisingly adept predator on land. Over evolutionary time, as fish stocks in fresh, shallow waters became depleted, an evolutionary change was forced on those species who survived the inital food shortage. And hence, the deep sea otter.
As the good hunting moved further out to sea, the river otter developed first specialized appendages to aid with the long distances needed to reach the richest shoals. Over time, these evolved to match the features of the shark, one of the most adept and efficient swimmers of the ocean deep. In addition, the deep sea otter, with the rich fishing available to them at the shoals far offshore, began to develop extra layers of fat, allowing them to dive deeper than any before, and endure the temperatures at depths where the sun's light was weak. The final, and most stunning adaptation of these deep sea otters, as compared to their fresh-water counterparts, was their adaptability to the low levels of oxygen found at greater depths, and the relatively sudden appearance and subsequent use of their gill system. Scientists still are baffled by the sudden appearance of this distinctly chordate feature, leading some to question the possibility of interbreeding with chordate species.
The lungs are just as capable of extracting the oxygen from the water as they are the oxygen of the atmosphere, although the lung must be processing whichever substance in which the otter is immersed, or drowning may occur (Langley, Staedtler, et al. Oceanographic Survey, MH, 2002). A relatively recent (in evolutionary terms) adaptation of the Deep Sea Otter lies in its symbiosis with the Panellus Stipticus fungus, the latter taking up residence at the exit of the hair follicle across the entire body. While the characteristic green glow can be readily seen at points where the hair (fur) is naturally thinner, it is mostly camouflaged by the thickness of the fur. However, it appears as though an as of yet unexplained glandular process releases Luciferin on demand, accelerating the oxidation of the fungus, and the resulting glow can be seen through the fur, apparently being controlled with great accuracy by the otter. Although several studies have been conducted on whether this process is used to attract prey, provide optical camoflauge, or act as a warning, none have yet been conclusive, as it appears that it may be a combination of all proposed purposes.
Finally, it should be noted that on the latest marine survey conducted off the Pacific coast of North America, one species was spotted at a depth of over 2500 feet, with a slightly different coloration, leading to speculation of an as of yet undiscovered sub-genus. Inital study suggests that the blue-green glow on the dorsal region of this specimen may in fact be natural bioluminescence, although peer reviewers have been largely divided on this hypothesis, as no specimen has yet been captured.

TL;DR
Okay, so if you bothered to read all that (or even if you didn't), here is the down low. Her last name, Foxfire, is a reference to that fungus, as it is commonly known as Foxfire. Blue and blue-green bioluminescence are most common on species at that depth, since they have the greatest range because of their wavelength, although there a few notable exceptions, such as the Tomopteris Nisseni (yellow) and the Black Dragonfish (red). The gills, although not stated, are a genetic defect originally caused by freshwater pollutants.

The green glow can be controlled to a point where it is almost invisible, while the stripes on her back can become completely indistinguishable from the tissue around it. One final note, when moving between air and water, she must fill her lungs with whichever she is moving in to .. from air to water, no problem; from water to air, however, there is always that awkward moment when she has to replace the water in her lungs with air, leading to her spewing water out of just about every orfice water can come out of.

Personality:
In short, maliciously playful. While not exactly a jerk in the strictest sense, she enjoys having fun at the expense of others. She enjoys stealing the catch of other predators, usually swimming or running circles around them while they either attempt to fight back, or plead and reason with her. Intelligent and witty, she can never resist an urge to needle another, regardless of friend status. Most common expressions: smug grin, shit eater smile, obviously feigned innocence, and occasionally fake anger when she doesn't get her way. She will always use any weakness to her advantage.

Likes
FISH
Warm sun and cold water
Teasing people

Dislikes
People beating her at her own game
Bugs
People following her
Fighting

Ref drawn by the lovely  Sin.