January 20, 2014
Here’s a video from yesterday’s dive at Pulau Hantu. A Marine flatworm (Pseudobiceros sp.) lifts off the coral reef and swims in mid-water. Watch how it alters the movement of its marginal ruffling to adjust its orientation and depth!
Locomotion of the marine flatworm consists of waves of extension and contraction on either side of the body, a pattern known as ditaxic locomotion (This means its foot is divided into left and right halves. A snail, for example, uses monotaxic locomotion). The waves begin at the anterior end and pass posteriorly along the length of the body, with left and right sides being out of phase with one another. The flatworm is able to maintain this ditaxic pattern even after suffering significant injury such as a tear along the length of the foot, sometimes due to fights with other flatworms, or an attack by a predator. Scientists believe that this suggests similar flatworms have a net-like type of nervous-system construction.