The Jestercup split from a deep sea-dwelling species of Giluksip, growing larger through abyssal gigantism. Similar to its ancestor, it waits for prey to pass overhead before stabbing it with its tooth and consuming it. Unlike its ancestor, however, to survive in the depths it has developed a feature which allows it to attract prey: bioluminescence.

The ends of the Jestercup’s gills are swollen and filled with symbiotic glow detritis. These attract potential food. With there being little light in the abyss, the Jestercup’s eyesight is nearly useless, so long filaments derived from the gill baits help it determine the prey’s size and position before thrusting its tooth into it. The bioluminescent bulbs at the ends of each arm cause the Jestercup to look like a jester’s hat, hence the name.

In order to survive in lower population densities, the Jestercup has developed its spawning ability even further: females can now release their gametes as well, eliminating live birth. They do not spawn eggs; the embryos develop unprotected, depending only on food that was stored in the female gamete’s vacuoles until they develop enough to start consuming cells and meiofauna. Larvae have an organ which bears resemblance to the lost ancestral waste funnel, which allows them to gather bioluminescent symbiotes; it is sealed off and atrophied during metamorphosis into bilateral adults. The end of the anal arm where its reproductive organs are is buried underground when not in use, as to protect it from predators.

The Jestercup will eat most swimming fauna up to 2 times its size, stretching to fit large catches in its blind gut. The tooth can pierce shells, but this can damage the tooth, so it will usually not strike if it feels a hard shell. Like its ancestor, it will usually sit still waiting for prey to come to it, but it can also uproot itself to swim away from predators in a similar fashion to a Terran anemone.