Abstract Diplopods are terrestrial arthropods important for the dynamics of terrestrial ecosystems. One of the reasons for that can be their low predation rate due to their defensive secretion. Thus, Orthoporus fuscipes, a species belonging to this group and endemic to northeastern Brazil, was investigated as to its population structure and chemical constituents of defensive secretion. The population structure showed that females are larger and have greater mass than do males, along with negative allometric growth between males and females. The defensive secretion hexane extract was submitted to fractionation using SiO2 open-column chromatography and the gas chromatographic coupled to mass spectrometric analysis was applied in the fraction possibilities to identify major fatty acid methyl esthers, along with minor alkanes, alkenes and fatty acids derivatives and the known quinoids 2-methoxy-3-methylhydroquinone, 2-methoxy-3-methyl-1,4-benzoquinone, 2,3-dimethoxy-1,4-benzoquinone and 2,3-dimethoxyhydroquinone. In addition, the cytochrome oxidase I sequence for the species was deposited for the first time. ecosystems Thus fuscipes Brazil SiO opencolumn open column esthers alkanes 2methoxy3methylhydroquinone, 2methoxy3methylhydroquinone methoxymethylhydroquinone 2 methoxy 3 methylhydroquinone, methylhydroquinone 2-methoxy-3-methylhydroquinone 2methoxy3methyl1,4benzoquinone, 2methoxy3methyl14benzoquinone methoxymethylbenzoquinone 1,4 benzoquinone, 1 4 benzoquinone 2-methoxy-3-methyl-1,4-benzoquinone 2,3dimethoxy1,4benzoquinone 23dimethoxy14benzoquinone dimethoxybenzoquinone 2,3 dimethoxy 2,3dimethoxyhydroquinone. 23dimethoxyhydroquinone dimethoxyhydroquinone dimethoxyhydroquinone. 2,3-dimethoxyhydroquinone addition time 2methoxy3methyl1 4benzoquinone 2methoxy3methyl1,4benzoquinone 14 1, 3dimethoxy1 23 2, 3dimethoxyhydroquinone 2,3dimethoxyhydroquinone methoxymethyl 2methoxy3methyl 3dimethoxy

Hoplosternum littorale é um peixe de respiração aérea continua que utiliza parte de seu intestino para a extração do oxigênio do ar. Este comportamento de respiração aérea realiza-se em quatro etapas: 1) Subida para a superfície da água; 2) Emergência da boca com a simultânea expansão da cavidade oral e inspiração; 3) Giro do corpo para baixo com compressão da cavidade oral e expiração do ar pelo ânus; 4) Retorno ao fundo. O tempo necessário para a realização do ciclo respiratório aéreo completo foi significativamente mais curto em indivíduos de menor tamanho quando comparados aos de maior massa corpórea.

Hoplosternum littorale is a continuous air breather, which uses a portion of its intestine to extract oxygen from inspired air. Its air-breathing behavior occurs in four phases: 1) ascent to the water surface; 2) mouth emergence with expansion of the oral cavity for air inspiration; 3) downward swimming and oral cavity compression resulting in air swallowing and the expiration of old air from the anus; 4) return to bottom. The time required to complete the air-breathing cycle was significantly shorter for small fish compared to large fish.