Journal of the Graduate School of Biosphere Science, Hiroshima University Volume 48
2009-12-25 発行

日本近海で採集されたマンボウ属(Mola spp. A and B)の形態異常個体

On the abnormally morphological forms in Mola sunfish (Mola spp. A and B) taken from Japanese coastal waters
Sawai, Etsuro
Yamanoue, Yusuke
Hashimoto, Hiroaki
Of 145 ocean sunfish specimens obtained from Japanese coastal waters between June 2007 and December 2008, morphologically abnormal forms were confirmed in a total of 18 specimens. Seven had transformed pectoral fins; two had shortened dorsal fins; one had abnormally arranged dorsal soft rays; one was missing the lower part of the clavus; one was missing the whole clavus; three had partially damaged bodies or fins, probably because of artificial cutting; two had hypertrophied testes; and one was a young fish in the juvenile-specific morphological form. These abnormal forms were thought to have occurred as a consequence of congenital malformation or damage by predation, parasites, humans, or other factors. One suffered a transformation in body shape from a natural form, probably because it was reared for a long period of time in an aquarium. According to the frequency of non-artifically abnormal individuals (ca. 10%, 14/145), the occurrence of abnormalities is not rare in natural populations.
abnormal form
external morphology
hypertrophied testes
Mola spp. A and B
reared specimens