Before continuing, I'd like to preface this by saying that I might've got a bit rusty. Also keep a thesaurus nearby, I wanted to make this use scientific jargon. Species name: Aquagale vampyra Common name: Splitleech Niche: Parasite Description: Descended from ancestral Aquags during prolonged algalga scarcity, Splitleeches have evolved into specialized, two-segmented parasites. The anterior "Feeder" segment attaches to algalga clusters (rare, often results in defunct spitleeches) or more commonly Aquags using hook-like keratinoid structures and a semi-flexible proboscis also tipped with barbed extensions. It absorbs material via a proboscis acting as a semi-permeable siphon, with nutrients processed minimally through absorptive skin and a short gut loop. The posterior "Reproducer" segment grows disproportionately as it stores nutrients, eventually detaching and regenerating a new Feeder. Splitleeches do not actively hunt and lack complex sensory organs, relying on passive feeding and segmental reproduction. The jaw, formed from fused segmental structures, opens at a permanent angle and cannot fully close. Due to this origin in merged segments, the jaw complex lacks full muscular articulation and instead relies on hydraulic pressure and skeletal tension, resulting in a perpetually agape state of ~45°. Populations increase during algalga busts when parasitic opportunities are more frequent. Minimum active adult size: ~3.5 cm (1.5 cm Feeder + 2 cm Reproducer) Maximum bloated size before splitting: ~7.5 cm (1.5 cm Feeder + 6 cm Reproducer) Extra: If under attack or environmental stress, the Reproducer can prematurely detach to preserve genetic material. This emergency split results in a smaller, slower-developing offspring but increases long-term survival chances. Inside the mouth-jaw complex remains primitive cilia, leftovers from their filter-feeding ancestry.
Extra lore, while ancestral Aquags developed 12–17 loosely defined post-cephalic segments, A. vampyra suppresses most segmental differentiation early in development. Though regeneration briefly follows the ancestral metameric blueprint, forming shallow segmental furrows within 48 hours post-detachment, these proto-segments are rapidly pruned through apoptosis or fusion into a syncytial sheath. This truncation is driven by overexpression of specific regulatory genes, which inhibit the full activation of segment-specific morphogens. As a result, only two major body regions form: the anterior “Feeder,” derived from roughly four ancestral segments and adapted for attachment and feeding; and the posterior “Reproducer,” is a hypertrophic, non-segmented structure for nutrient storage and reproduction.
