The bite. Two punctures in the throat.

Every human has a frenulum: a thin mucous band tethering tongue to floor of mouth. In the haemophage that structure is neither thin nor passive. The sublingual glands hypertrophy to roughly six times original volume. Acinar salivary cells are replaced by helical smooth-muscle fibre — the same peristaltic architecture as oesophagus and gut. The result is a muscular tube approximately fifteen centimetres fully extended, sheathed in tough mucosa, with an internal diameter sufficient for significant blood flow.

The distal tip is lined with mechanoreceptors that have no baseline-human homologue. They read subcutaneous vessels two ways at once: pressure variation from arterial pulse, and the fractional thermal gradient between tissue over a major vessel and tissue without one. Combined, it is a biological ultrasound. The organ does not probe blindly. In a practised host it seats on a target vein or artery within seconds, then applies both suction and reverse peristalsis from a muscular expansion chamber at the base — the pharyngeal pump of a leech, rebuilt under a human tongue. Combined flow extracts approximately 470 millilitres in under three minutes. The two punctures in the folklore are the canines holding the wound open. The blood leaves through the thing nobody saw.