Abnormal embryos of sharpnose sharks, Rhizoprionodon porosus and Rhizoprionodon lalandii (Elasmobranchii: Carcharhinidae), from Brazilian coast, western South Atlantic

Abstract

This study presents the second worldwide report on abnormal embryos of the sharpnose sharks, Rhizoprionodon, based on the two species (Rhizoprionodon porosus and Rhizoprionodon lalandii) occurring on the Brazilian coast. For R. porosus two conjoined twin embryos showing complete duplication of the vertebral column, viscera and several external structures (head, first and second dorsal fins, pectoral fins), and scoliosis in both axis at the pelvic fin level are reported. The three embryos of R. lalandii exhibited numerous lordosis and kyphosis along the entire vertebral column. The possible relationship between anomalies and the human major threats to sharks is discussed based on previous reproductive, genetic and ecotoxicological studies on R. lalandii for southern Brazil.

Morphological and functional abnormality in the spiny butterfly ray Gymnura altavela

“…The present communication is not only the first description of an elasmobranch disorder in the Canary Archipelago, but also a novel report for recording the first anomaly in G. altavela, and observing the individual in its natural habitat on several occasions, with different activities, and with a resighting after one year. Numerous anomaly reports were obtained from catch landings of free swimming elasmobranchs (Blanco-Parra and Niño-Torres 2011; Capapé et al 2015a;Capapé et al 2015b; Castro Aguirre and Torres Villegas 1979; Dalù et al 2003;El Kamel et al 2009;Forster 1967;Gudger 1933;Honma and Sugihara 1971;Metin et al 2009;Mnasri et al 2010;Moore 2015;Nunes and Piorski 2009;Orlov 2011;Ramírez-Hernandez et al 2011;Ribeiro-Prado et al 2008;Sandoval-Castillo et al 2006;dos Santos and Gadig 2014;Valle 1931), but none of them observing the specimen actively in its environment. Five out of the six reported anomaly cases in the genus Gymnura describe unfused pectoral fins.…”

“…Castro Aguirre and Torres Villegas (1979) pointed out early the lack of research corroborating teratogens that cause congenital disorders. The need for more detailed studies on abnormal embryos linked to the embryological, genetic and ecotoxicological approaches as highlighted by dos Santos and Gadig (2014) is underlined with this case.…”

Abnormalities in two shark species, the blue shark, Prionace glauca, and the school shark, Galeorhinus galeus (Elasmobranchii: Carcharhiniformes), from the Canary Islands, eastern tropical Atlantic

“…Many of the morphological abnormalities have mainly been recorded in the embryonic phase. In sharks, the bicephalism and diprosopia anomalies have been documented in placental viviparous (Goto et al 1981, Muñoz-Osorio et al 2013, Dos Santos and Gadig 2014 and aplacental viviparous (Lozano- Cabo 1945, Delpiani et al 2011, Sans-Coma et al 2016, Capapé and Ali 2017. Although these congenital morphological abnormalities are poorly understood, they can be due to several causes, either natural or anthropogenic (Heupel et al 1999, Moore 2015.…”

Record of morphological abnormality in embryos of Caribbean sharpnose shark, Rhizoprionodon porosus (Elasmobranchii, Carcharhinidae), from the south coast of São Paulo State, Brazil

“…There are few studies addressing the anomalies in Elasmobranchii, however the cases have been gradually increasing. Dicephaly, cephalic malformation and albinism are some published reports for sharks (5,6,7,8). Little is known about the reasons that could lead to these deformities and further research is needed leading to a better understanding of the cases.…”