From 2speccers2tools wiki

When some populations of Ripplets began to intrude upon The Fucking Trench, the found both great opportunity but also great hardship. To adapt to these environments, they would develop some radical adaptations that would lead to them becoming the deep-sea dwelling species known as the Ghastlets.

The fins of the Ghastlet have hardly changed at all, each one still being a rigid seta-derived skeletal projection that creatures rapid movements for fast hydrodynamic propulsion. The caudal fin derived from sclerotized cirri has become much larger to provide more rapid bursts of speed. The skeletal system of the Ghastlet has become thinner and more flexible than their ancestor or relatives, since they need to take the large pressure that comes with living in such great depths. The skeletal system does still, however, provide muscle attachments.

The depths of the trench are both low in light and oxygen, which meant the Ghastlet required several adaptations to make a living. To deal with low oxygen levels, the feathery gills have become much larger to increase the overall surface area for oxygen to diffuse into their bloodstream (which still contains hemoorangin-bearing cells) while the lower pair of pores still expels waste gases. The asshole-line derived heart has also grown much bigger to pump blood more quickly and thus make more use out of the oxygen they can obtain from the water. The eyes have become absolutely enormous, with all four pairs being relatively similar in size and having developed a tapetum lucidum to get as much light as possible since so little of it trickles down into the depths. This allows the Ghastlet to see much more clearly in the depths than almost all of its prey, while its dark reddish-brown coloration helps it blend in with the darkness when on the hunt. If the Ghastlet comes across prey, it will stretch out its mouth to snag the victim with their enormous teeth(which are derived from ancient bruh cells). The teeth are so enormous that the Ghastlet is unable to even fully close its mouth, acting like a trap to keep prey in while they become ingested. The digestive tract has developed a truly enormous intestine, so they can get as much energy as possible from their consumed prey as it may be a long while before they find something else to consume again. Their immunity to spite and high tolerance of radiation allows the Ghastlet to take advantage of whatever kinds of prey dwell within the trench since they cannot afford to be picky.

Much like their ancient ancestors, the Ghastlet reproduces through spawning, through they only do it when they bump into one another. Gametes are sent into the water which form innumerable fertile eggs, in turn hatch into small larvae. Larval Ghastlets are primarily scavengers that feed upon carcasses that sink into the trench from the waters above as well as feeding upon the small microbes that live within the depths. In turn, the larval Ghastlets provide an energy-rich source of food to many predators, including adult Ghastlets, cementing their integral position in the abyssal food web.