Lancelet
. Lancelet, also called amphioxus, primitive fishlike animal that lacks a backbone but has many characteristics of vertebrates (animals with backbones). Many scientists believe that vertebrates may have evolved from an early ancestor similar to lancelets. Lancelets occur worldwide in shallow, marine environments, where they burrow into loose gravel or sand, leaving only their mouths protruding. Some Asian people consider lancelets a great delicacy, and the animal is commercially harvested in China. Lancelets grow to a length of about 5 cm (2 in). They have an eel-like body shape with a well-defined mouth and tail. Most are semitransparent. Lancelets share a number of features in common with vertebrates, including a dorsal nerve cord that is supported by a stiff rod known as the notochord—a forerunner of the backbone; a system of pharyngeal slits between the mouth and stomach, used to strain food particles from water; and a series of segmented, V-shaped muscles along the torso. Unlike ...