ABSTRACT
The hammerhead sharks shows a head laterally expanded with eyes and nostrils on the edges, which gives the species a hammer appearance. Another strand of studies indicates that the hypothesis of head shape alterations for better adaptions in the sensorial system with the development of structures associated to binocular sight and others sensorial organs. Given the variety of characteristics, the study aim was to describe the anatomical constitution of the hammerhead shark eye bulb. The bulb and its annexes exenteration was performed, and further dissection; the morphological description of the muscle insertions and eye bulb components were based on direct observation and were further photographed and catalogued. The eye bulb fragments and its annexes were histological technical. Between the sclera and the choroid it was possible to observe, by the electronical scanning microscopy, the thin layer called supra-choroid, in this region, spaces often filled by lymphatic vessels allied to a matrix formed by loose conjunctive tissue are found. In the choroid, a layer which is rich in blood vessels, loose conjunctive tissue and collagen fibers, was observed, besides pigmentary cells full of melanin in its interior, which result in its layer's dark color. Ciliary body is a choroid's dilatation; it has the aspect of a thick ring in finger-like shape, pigmented, covering the sclera surface and containing pigmentary cells. The crystalline capsule, which shows an acellular covering that, is hyaline and homogeneous. In the electronical scanning microscopy, it was observed that the capsule is extremely thick especially in the anterior face. The capsule is very elastic, constituted mainly by thin lamellae of collagenous fibers, as illustrated by the electronically scanning microscopy. Anatomic variations related mainly to the position of the eye bulb in the skull, fibrous tunica and lens call the attention and must be related to its habitat.
El tiburón martillo tiene la cabeza lateralmente expandida con los ojos y la nariz en sus márgenes. Estudios indican que alteraciones de la forma de la cabeza de estos animales son adaptaciones que mejoran el desarrollo del sistema sensorial y estructuras asociadas a la visión binocular y otros órganos sensoriales. Dada la variedad de características, el objetivo del estudio fue describir la constitución anatómica del bulbo ocular. Se disecó el bulbo ocular junto a sus anexos. La descripción morfológica de las inserciones musculares y componentes del bulbo ocular se basaron en la observación directa, siendo éstas fotografiadas y catalogadas. Entre la esclera y la coroides se observó através de microscopía electrónica de barrido, una delgada capa supra-coroides, y vasos linfáticos junto a la matriz formada por tejidos conectivos. La coroides, era abundante en vasos sanguíneos y fibras de tejido conectivo. Se observaron escasas células pigmentarias llenas de melanina, lo que se asemeja a un anillo en forma de dedo, de manera que cubren la superficie de la esclera y células que contienen pigmentos. En la cápsula del lente, fue posible observar un recubrimiento celular, hialino y homogéneo. En la microscopía electrónica de barrido, se observó una cápsula muy gruesa, principalmente en la región frontal. La cápsula elástica,estaba constituida por láminas delgadas, principalmente, por fibras de colágeno. Se concluyó que el bulbo ocular de estos animales posee variaciones anatómicas relacionadas, principalmente, con la posición del bulbo ocular en el cráneo, túnica fibrosa y lente, lo que puede estar directamente relacionado con su hábitat.
Subject(s)
Animals , Eye/anatomy & histology , Sharks/anatomy & histology , Eye/ultrastructure , Microscopy, ElectronABSTRACT
Abstract Catches and exports of skate Rioraja agassizii place this species as “vulnerable to extinction” on the IUCN Red List; therefore, biological and ecological knowledge becomes an important instrument for its conservation control. This study described and quantified the diet composition of R. agassizii by means of stomach analysis contents in the periods 2005-2006 and 2012-2013. We analyzed and quantified stomach contents in terms of abundance (%N), weight (%M), frequency of occurrence (% FO), and index of relative importance (IRI). The results showed differences in the food rates between the periods. However, the groups of food items were the same: Teleostei fish, decapods, and mollusks. In 2005-2006, the diet consisted mainly of shrimp, however, in 2012-2013 it consisted of fish, followed by decapods, especially shrimps. The differences in diets may be attributed to shrimp abundance, which do not characterize a change in the eating habits in 2012-2013, because, in addition to fish, shrimps were also important food sources. The presence of a certain prey is more related to its availability rather than the feeding preference of skate. The amount of ingested items is associated to biological and environmental factors, so that further studies relating diet with capture area, seasonality, depth, and other factors should be conducted.
Resumo A raia-santa, Rioraja agassizii é uma espécie endêmica da qual pouco se conhece sobre sua biologia e ecologia, o que a leva a ser classificada como “vulnerável a extinção”. O objetivo foi identificar e quantificar a composição da dieta alimentar da R. agassizii através da análise do conteúdo estomacal de exemplares capturados nos períodos de 2005-2006 e 2012-2013. Foram analisados os conteúdos alimentares e quantificados em abundância (N%), peso (M%), frequência de ocorrência (FO%) e índice de importância relativa (IRI) de cada item. Os resultados mostraram que em 2012-13 a dieta foi composta por peixes, seguido de decápodes, especialmente camarões, entretanto em 2005-06 foi composta basicamente por camarões. A diferença nas dietas não quer dizer que os hábitos alimentares mudaram, pois em 2012-13 além dos peixes, os camarões também foram classificados como maior importância alimentar. Considerando que a quantidade e variedade dos itens ingeridos está relacionada, principalmente, a fatores ambientais são necessários mais estudos que relacionem áreas de captura, sazonalidade e profundidade.
Subject(s)
Animals , Skates, Fish/physiology , Feeding Behavior/physiology , Gastrointestinal Contents , Seasons , Decapoda , Brazil , EcosystemABSTRACT
Relata-se a ocorrência de Rhinoptericola megacantha (Cestoda, Trypanorhyncha) parasitando duas raias da espécie Rhinoptera brasiliensis, de um total de sete espécimes analisados. Foram encontrados três espécimes do cestóide, que havia sido descrito ocorrendo apenas no hospedeiro Rhinoptera bonasus capturado em Virginia (EUA), Golfo Venezuelano e Golfo do México. Este é o primeiro relato da ocorrência de R. megacantha no hospedeiro R. brasiliensis e primeira ocorrência no Brasil deste cestóide.(AU)
Subject(s)
Animals , Skates, Fish/parasitology , Cestoda , BrazilABSTRACT
Uteri from four pregnant females and two newborn of shortfin mako, Isurus oxyrinchus, were collected in the southeastern region of Brazil, during September, October, and November of 1993 and 1994. All embryos were near-term with developing dentition and inner organs. Total length ranged from 64.5 to 72.0 cm, and the maximum number of embryos observed in a litter was 20. These observations further confirmed oophagy as a form of nutrition in this species, and its periodicity. The presence of teeth in the embryos' stomachs suggest that tooth replacement begins in the uterine phase
Subject(s)
Animals , Pregnancy , Male , Female , Embryo, Nonmammalian , Sharks , Biometry , Brazil , Dentition , Embryo, Nonmammalian , ReproductionABSTRACT
Foi feita a comparacao de dois metodos de diagnostico usados para a identificacao do Trichomonas vaginalis. A comparacao estatistica das duas tecnicas que o metodo de cultura e superior ao exame a fresco