Longitudinal Observation of Japanese Lancelet, Branchiostoma japonicum, Metamorphosis
Figure 3
Size reduction and change of digestive system. (a) Chronological change of the specimen number 1 in Figure 2(a). Note the remarkable reduction of the pharyngeal length and moderate reduction of the esophagus and midgut region as well as remarkable elongation of the intestine. (b) Reduction of body length in five individuals compared with the length at the beginning of the observation. Line colors are the same as those in Figure 2(a). Reduction of the body length is maximized when left and right gill rows become paired. Animal images numbered 1–5 are as follows: 1, on 17 September; 2, on 25 September; 3, on 30 September; 4, on 9 October; and 5, on 17 October. an: anus; ap: atriopore; at: atrium; ep: esophagus; hd: hepatic diverticulum; in: intestine; ir: iliocolonic ring; lm: larval mouth; pg: primary gills; sg: secondary gills; sgo: secondary gill openings; sy: synapticle; tb: tongue bars; ve: velum.
