The pale headshield slug of open sand, hunting flatworms along their mucus trails.
A headshield slug to about 4 cm, the body cream to white with a dark brown to black band running right around the margin — head shield, parapodial flaps and tails alike — and a fine pale line outside it. The rear of the foot is drawn out into two unequal tails, the left longer than the right, as in the rest of the genus. The other two seen on the same ground are darker: Chelidonura varians is velvet black with electric blue lines, and C. hirundinina carries orange and blue on a dark ground. This is the pale one, and on light sand it is easier to miss than either.
Like the rest of them it is a cephalaspidean rather than a nudibranch, and the flattened shield across the front of the head is the structure that lets it plough through sediment without the sediment entering the mantle cavity.
Hunts acoel flatworms, following their mucus trails across sand and algae film and engulfing them whole with a muscular pharynx — it has no radula. An animal moving in a purposeful straight line across open sand is on a trail, and it will not stop or turn for a diver, so the frame is taken by getting ahead of it and waiting. Active in daylight. Recorded from the shallows to about 25 m.
Ratings are per location: 1 means found on most dives that look for it, 5 means a handful of records. Where enough dives have been logged the figure is calculated from them; otherwise it is an editorial estimate, and says so. We publish habitat and destination, not the dive site.
