title: A preliminary investigation into the morphology of oral papillae and denticles of blue sharks (Prionace glauca) with inferences about its functional significance across life stages.
abstract: Sensory organs in elasmobranchs (sharks, skates, rays) detect and respond to a different set of biotic and/or abiotic stimuli, through sight, smell, taste, hearing, mechanoreception and electroreception. Although gustation is crucial for survival and essential for growth, mobility, and maintenance of neural activity and the proper functioning of the immune system, comparatively little is known about this sensory system in elasmobranchs. Here we present a preliminary investigation into the structural and dimensional characteristics of the oral papillae and denticles found in the oropharyngeal cavity of the blue shark (Prionace glauca) during embryonic development through adulthood. Samples were obtained from the dorsal and ventral surface of the oropharyngeal cavity collected from embryos at different development stages as well as from adults. Our results suggest that development of papillae occurs early in ontogeny, before the formation of the oral denticles. The diameter of oral papillae gradually increases during development, starting from 25 μm in stage I embryos, to 110 μm in stage IV embryos and 272-300 μm in adults. Embryos exhibit papillae at early developmental stages, suggesting that these structures may be important during early in life. The highest density of papillae was observed in the maxillary and mandibular valve regions, possibly related to the ability to identify, capture and process prey. The oral denticles were observed only in the final embryonic stage as well as in adults. Accordingly, we suggest that oral denticles likely aid in ram ventilation (through reducing the hydrodynamic drag), to protect papillae from injury during prey consumption and assist in the retention and consumption of prey (through adhesion), since these processes are only necessary after birth.
authors.affiliation: Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil.|Departamento de Cirurgia da Faculdade de Medicina Veterinária e Zootecnia da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Bianca de S
authors.initials: BS
authors.lastname: Rangel
authors.affiliation: Departamento de Fisiologia, Setor de Ciências Biológicas, Centro Politécnico, Universidade Federal do Paraná, Curitiba, Paraná, Brazil.
authors.forename: Natascha
authors.initials: N
authors.lastname: Wosnick
authors.affiliation: Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL, USA.|Abess Center for Ecosystem Science and Policy, University of Miami, Miami, FL, USA.
authors.forename: Neil
authors.initials: N
authors.lastname: Hammerschlag
authors.affiliation: Laboratório de Morfologia, Instituto de Biociências, Universidade Estadual Paulista, Rio Claro, São Paulo, Brazil.
authors.forename: Adriano P
authors.initials: AP
authors.lastname: Ciena
authors.affiliation: Departamento de Cirurgia da Faculdade de Medicina Veterinária e Zootecnia da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: José Roberto
authors.initials: JR
authors.lastname: Kfoury Junior
authors.affiliation: Departamento de Cirurgia da Faculdade de Medicina Veterinária e Zootecnia da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Rose E G
authors.initials: RE
authors.lastname: Rici
mesh_terms: D000818:Animals; D009960:Oropharynx / Q000033:anatomy & histology*; D012754:Sharks / Q000033:anatomy & histology*
keywords: embryonic development; feeding behavior; gustation; oropharyngeal cavity; ram ventilation