Schlängelschwimmen (vorwärts u. rückwärts) des Lanzettfischchens: sinusförmige Körperkrümmungen aufgrund phasenverschobener Kontraktionen der Seitenrumpfmuskulatur (Myotome); Eingraben (meist rückwärts): korkenzieherartige Bewegungen des muskulösen Schwanzes, Kopf außerhalb des Sediments. Mit Zeitdehnung.

This film shows adult Branchiostoma lanceolatum swimming and burrowing in the sand. Normally they live buried in the sand, with only their fore-ends projecting, and swim only if disturbed by some stimulus or when it is necessary for spawning. They swim with lateral sinuous movements which permit them to move both forwards and backwards and to change direction quickly. Usually motion in a forward direction is combined with clockwise rotation of the body. They are also able to burrow in the sand both forwards and backwards; the backwards position is more common. The position of lancelets buried in the sand is characteristic: Whereas animals which have burrowed forwards have a simple curve in their bodies, those which have burrowed backwards retain the shape of their sinuous swimming motion. The body forms a W.