Long-term body pigmentation changes on a manta ray (Mobulidae)

Abstract

Manta rays (genus Manta) are listed as vulnerable on the IUCN Red List based partly on population studies that use body coloration and ventral spot patterns to identify and count individuals, as a result of such patterns being considered unique and permanent during their lifetime. The present study reports the first evidence of long-term coloration changes of manta rays based on observations of one captive individual. Darkening skin pigmentation was documented on the side of the head, the inner side of the cephalic lobes and the pectoral fin margin of the ventral side, and spot markings appeared on the gill slits within 9 months. These changes were most likely ontogenetic or were connected to maturation. The described specimen's coloration did not fulfill the taxonomic classification criteria of either manta ray species and rather resembled two different manta ray species at the beginning and end of the study. These results show that coloration patterns of manta rays are not as stable as has been assumed previously. Further studies are needed to identify the extent of such changes for accurate identification and classification of manta rays.