<b>Ultrastructural aspects of the tongue in Magellanic Penguins <i>Spheniscus magellanicus</i> (Forster, 1781)

Abstract

ABSTRACT. The tongue of birds presents diversified morphologic characteristics, related directly their feeding habits and may be adapted to food capture. Penguins of the Spheniscidae family are pelagic birds that are totally adapted to the marine environment. The objective of this study was to describe the morphology of the tongue in Magellanic penguins (Spheniscus magellanicus). In order to investigate these characteristics, six tongues of juvenile S. magellanicus were collected and their morphology analyzed macroscopically and microscopically. The tongue of the Magellanic penguin has a fusiform shape with a round apex that is narrower than the root, following the shape of the beak. The epithelium of the tongue of the Magellanic penguin showed to be stratified and very keratinized, with the presence of lingual papillae that showed a caudally inclined apex. The neighboring connective tissue showed absence of mucous glands. The cartilaginous skeleton was observed in the medial region of the tongue, extending from the base to the apex. The structure of the tongue of the Magellanic penguin showed to be similar to that of other penguin species, but also showed peculiar characteristics that were not observed in other bird families.Keywords: lingual papillae, morpuology, Spheniscidae, ultrastructure.Aspectos ultraestruturais da língua de Pinguim-de-Magalhães Spheniscus magellanicus (Forster, 1781) RESUMO. A língua das aves apresenta características morfológicas diversificadas, relacionados diretamente com seus hábitos alimentares e pode ser adaptado para a captura de alimentos. Os pinguins da família Spheniscidae são aves pelágicas totalmente adaptadas ao ambiente marinho. O objetivo deste estudo foi descrever a morfologia da língua de pinguins de Magalhães (Spheniscus magellanicus). Para investigar tais características, seis línguas de S. magellanicus juvenis foram coletados e sua morfologia analisada macro e microscopicamente. A língua do pinguim de Magalhães tem formato fusiforme com ápice arredondado e mais estreito em relação à raiz, acompanhando o formato do bico. O epitélio da língua do pinguim-de-Magalhães mostrou-se estratificado e muito queratinizado, com a presença de papilas linguais, com ápices voltados caudalmente. O tecido conjuntivo adjacente mostrou ausência de glândulas mucosas. Um esqueleto cartilaginoso, formado por cartilagem hialina, foi observado na região mediana da língua se estendendo da base até ápice. A estrutura da língua do pinguim Magellanic mostrou ser semelhante ao de outras espécies de pinguins, mas também apresentou características peculiares que não foram observados em outras famílias de aves.Palavras-chave: papila lingual, morfologia, Spheniscidae, ultraestrutura.

Comparative Morphological, Ultrastructural and Histological Studies on the Tongue of Eurasian Wigeon )Anas penelope) and Northern Shoveler )Anas clypeata)

“…This finding is obviously different from the keratinized lingual epithelium detected in Japanese quail (Warner et al, 1967) and in most birds as reported by Kobayashi et al (1998). the tongue of the Magellanic penguin showed a highly keratinized epithelium both in the dorsal and ventral regions (Guimarães et al, 2014) as it was observed with other penguin species (Kobayashi et al, 1998) and in other birds, the cormorant (Jackowiak et al, 2006), the oriental scops owl, and the Japanese pigmy woodpecker (Emura et al, 2009 a, b), whose feeding habits depend on a more rigid and resistant tongue structure. Our study showed that the dorsal surface of the lingual apex of ansa clypeata is thicker than the dorsal surface of the lingual apex of anas Penelope.…”

“…Comparative studies that have been made on the tongue of different vertebrate species suggest morphological adaptations throughout the process of evolution. These evolutionary changes are considered the principles for the progress in food intake and occupation of different habitats (Iwasaki, 2002 andGuimarães et al, 2014).…”

Relating form to function in the hummingbird feeding apparatus

“…Hummingbird tongues entirely lack papillae, a rare condition in vertebrate tongues ( Schwenk, 2000 ; Iwasaki, 2002 ) and even among birds (review in Erdoğan & Iwasaki, 2014 ). Avian lingual papillae are involved in manipulation of solid food (e.g., prey apprehension, holding, cutting, filtering, shelling, Iwasaki, Asami & Chiba, 1997 ; Kobayashi et al, 1998 ; Jackowiak et al, 2010 ; Jackowiak et al, 2011 ; Guimarães et al, 2014 ; Skieresz-Szewczyk & Jackowiak, 2014 ) and caudal intraoral transport of solid items (review in Parchami, Dehkordi & Bahadoran, 2010 ). Hummingbirds have remarkable feeding modes; first, about half of their diet (cf.…”

Peer Review #2 of "Relating form to function in the hummingbird feeding apparatus (v0.1)"

“…Avian lingual papillae are involved in manipulation of solid food (e.g. prey apprehension, holding, cutting, filtering, shelling, Iwasaki et al 1997;Kobayashi et al 1998;Jackowiak et al 2010;Guimarães et al 2014;Skieresz-Szewczyk and Jackowiak 2014) Harper et al 2013) or lorikeets (Homberger 1980, p. 41). Second, the other half of their diet (cf.…”