Unlike most Tyranid bio-ships, the Narvhal is almost completely defenceless, and possesses almost no bio-weaponry and only a very thin protective carapace. A cluster of monofilament spines on the Narvhal's bow allow it to take in a wide variety of sensory input, including a broad spectrum of gravimetric and electromagnetic signals. Using these sensors, the Narvhal can detect new planetary systems at extreme interstellar distances. In some unknown manner it then makes use of the origin star system's own gravity and creates a compressed space-time transit corridor through which the Narvhal and other Tyranid bio-ships can traverse interstellar distances. This form of space-warping travel cannot be used near strong gravitational sources as they overwhelm the Narvhal's hypersensitive navigation