Umbrajet

When xxeljets would begin to move away from the Rhodix Vents, they began to change and evolve to take advantage of whatever prey they came across. Over time, they would move away from filter feeding and become obligate hunters, splitting off from the xxeljets that stayed around the vents and becoming a unique taxon of their own right. Known as the umbrajet, living in the deep depths has allowed them to quickly balloon in size, making them by far the largest xxeljets to have yet evolved. This greater size allows the umbrajet to tackle larger game, which is important in the deep depths since any creature they come across is something worth attacking in case it can be eaten.

The main changes in terms of its anatomy reflect their change in diet, as the membranes that line the four mandibles of the umbrajet have been reduced in size since they no longer capture plankton. Instead, the mandibles are thicker and have larger serrated ends that interlock, allowing it to grab and restrain prey, while the long proboscis still utilizes its simple jaw with serrated edges to rip off chunks of meat to then be swallowed. The two mouths can still both be used for feeding, as once the meal is small enough between the mandibles the umbrajet can swallow it whole, but it can only do that when it's been ripped apart enough.

Of course, the umbrajet actually needs to catch something before it can begin feeding, which is why its eyes have grown to gigantic proportions. This is because the species uses their enormous eyes to gather as much visual information as they can in the dark depths, looking for any signs of bioluminescent lights or the vague silhouette of something moving for it to then lock onto. If it does indeed detect something, the umbrajet will spring into action, using its methane producing chamber at the back end of their body as a jet to rapidly swim towards their target. The paired flippers seen in other xxeljets help this species make sharp turns while jetting around, so it can pursue a fleeing victim, while the dorsal spines help with stability so the umbrajet does not flip over while turning. These adaptations, alongside its darker coloration to better blend into the dark abyss, are also useful for helping the umbrajet with avoiding predators as it's not the largest thing swimming around in the dark depths.

The umbrajet has made a few significant changes from their ancestors in terms of reproduction. When an individual has eaten enough and has plenty of energy to spare, they will release pheromones into the water. If another umbrajet that has also been well fed tastes these pheromones, it will proceed to release gametes into the water column, which float around for a while until they hit the gametes of other individuals and fuse together, becoming a true spore that will then grow and develop into a new umbrajet. As they too also release pheromones into the water, it quickly results in a chain reaction where any umbrajets in the area that have been well fed and pick up the pheromones will then broadcast spawn in a short period of time, which in turn greatly increases the chances of the gametes germinating. If an individual does not detect the pheromones of another umbrajet for a long period of time, it will rely on parthenogenesis instead, self-fertilizing their own gametes and producing identical clones of themselves. By having such a variable reproductive strategy, the umbrajets are able to increase genetic diversity while also being able to fall back on cloning when potential mates are scarce.