Decussation as an axial twist: A comment on Kinsbourne (2013).

One of the great mysteries of the brain, which has puzzled all-time students of brain form and function, is the contralateral organization of the forebrain and the crossings of its major afferent and efferent connections. As a novel explanation, two recent studies have proposed that the rostral part of the head, including the forebrain, is rotated by 180° with respect to the rest of the body (de Lussanet and Osse, 2012; Kinsbourne, 2013). Kinsbourne proposes one 180° turn while we consider the 180° being the result of two 90° turns in opposite directions.

Structure and function of the median finfold in larval teleosts.

This paper offers a structural and mechanical analysis of the median finfold in larval teleosts. The median finfold is strengthened by bundles of collagen fibres, known as actinotrichia. We demonstrate that these structures contribute to increase the mass of backward accelerated water during swimming.

Effect of low ambient mineral concentrations on the accumulation of calcium, magnesium and phosphorus by early life stages of the air-breathing armoured catfish Megalechis personata (Siluriformes: Callichthyidae).

The accumulation of calcium, magnesium and phosphorus was measured during an 8-week period in the early life stages of the air-breathing armoured catfish Megalechis personata acclimated to low-mineral fresh water (0.073 mmol l-1 calcium, 0.015 mmol l-1 magnesium, <0.

Intra-oral food manipulation of carp and other cyprinids: adaptations and limitations.

The heterogeneity of the cyprinid fishes (about 2000 species) and their feeding requires a general model of aquatic feeding. In this model the timing of mouth and gill slit opening and the relative contribution of head expansion and swimming are determining factors. The following elements have been distinguished in the feeding process of cyprinid fishes: search/choice, intake (particulate intake and gulping), size-and taste selection, intra-oral transport (including repositioning), mastication and deglutition.

Local differences in myotendinous junctions in axial muscle fibres of carp (Cyprinus carpio L.).

We studied the myotendinous junctions of anterior and posterior red and white axial muscle fibres of carp using stereology. In posterior axial muscle fibres of swimming fish, stress (load on the myotendinous junction) must be higher than in anterior fibres as posterior fibres have a longer phase of eccentric activity. As we expected the magnitude of the load on the junction to be reflected in its structure, we compared the interfacial ratio, the ratio between the area of the junctional sarcolemma and the cross-sectional fibre area, of these muscle fibres.

IMPLICATIONS OF GILL ARCH MOVEMENTS FOR FILTER-FEEDING: AN X-RAY CINEMATOGRAPHICAL STUDY OF FILTER-FEEDING WHITE BREAM (BLICCA BJOERKNA) AND COMMON BREAM (ABRAMIS BRAMA).

Previous research shows that the reducible-channel model of filter-feeding can probably be applied to common bream, but not to white bream. According to this model, zooplankton are retained in the channels between the medial gill rakers; the mesh size of the sieve can be reduced by lowering the lateral rakers of the neighbouring gill arch into these channels. Gill arch movements may well disturb this mechanism; the depressed lateral gill rakers will move in and out of the medial channels and also shift out of their centre.

Numbers of myosatellite cells in white axial muscle of growing fish: Cyprinus carpio L. (Teleostei).

By means of transmission electron microscopy (TEM), the percentage of myosatellite cells was shown to decrease from about 6% in carp of 5 cm standard length (SL) to less than 1% in carp larger than 18 cm SL. The ratio between muscle nuclei and non muscle nuclei remained constant. These TEM data, combined with data on the amount of DNA per gram of muscle tissue and per nucleus, were used to calculate the numbers of myosatellite cells per gram of tissue (TEM-DNA method).

A functional explanation for a sequence of developmental events in the carp. The absence of gills in early larvae.

The animal body is composed of structural elements which can be characterized by their size, position, external form, internal structure and their participation in functions. Their presence is taken for granted. The ontogenetic sequence of development of functional systems in fish shows an early absence of gills although effective and fast suction feeding movements are already found in 6 mm larvae.

Model of jaw depression during feeding in Astatotilapia elegans (Teleostei: Cichlidae): Mechanisms for energy storage and triggering.

Suction feeding in Astatotilapia elegans occurs by a series of rapid, coupled movements of various head parts. The lower jaw rotates with respect to the neurocranium through an angle of 62° in less than 15 ms. The power requirements for jaw depression are calculated from a mathematical model and may reach a peak of ±4 watt in a 12-cm-long specimen.

Functional morphology of the feeding system in the ruff - Gymnocephalus cernua (L. 1758) - (Teleostei, Percidae).

The ruff, Gymnocephalus cernua, is a European freshwater fish that feeds by sucking up small invertebrates from the bottom of ponds and slow flowing rivers. The feeding movements have been studied by simultaneous electromyography of seventeen muscles of the head and cinematographic techniques. A theoretical model of movements imposes the functional demands of suction upon an abstraction of the form of a teleost head.