Basic reporting

This paper adheres to the PeerJ policies and structure and although is not meant to test a hypothesis provides a valid insight into the range extension of Manta birostris.

Experimental design

No Comments.

Validity of the findings

The authors' findings shed additional information on the world's largest ray, and should be published. The manuscript should however include additional information on known prey species occurring at the sites during the observation periods as well as general temperatures preferred by M. birostris. Information on the temp and depth during the second sighting and the most annual temperature ranges recorded at both observation sites, notably at 40 degrees S should also be included. Published insights or linkages to "exceptional oceanographic conditions occurring in the area at the time of the sighting" are recommended. These will help to better place this paper's findings in the context of known Mb ecology.