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Syngnathid fishes (seahorses, pipefish, and sea dragons) possess a highly modified cranium characterized by a long and tubular snout with minute jaws at its end. Previous studies indicated that these species are extremely fast suction feeders with their feeding strike characterized by a rapid elevation of the head accompanied by rotation of the hyoid. A(More)
It is generally assumed that biting performance trades off with suction performance in fish because both feeding types may place conflicting demands on the cranial musculo-skeletal system. However, the functional consequences of morphological adaptations enhancing biting on the mechanics and performance of suction feeding in fish remain obscure. In this(More)
The effects of the synthetic estrogen 17alpha-ethinylestradiol (EE) on sexual development of the freshwater amphipod Hyalella azteca was investigated. Organisms were exposed in a multigeneration experiment to EE concentrations ranging from 0.1 to 10 microg/L and the development of both external and internal sexual characteristics were studied.(More)
The long snout of pipefishes and seahorses (Syngnathidae, Gasterosteiformes) is formed as an elongation of the ethmoid region. This is in contrast to many other teleosts with elongate snouts (e.g., butterflyfishes) in which the snout is formed as an extension of the jaws. Syngnathid fishes perform very fast suction feeding, accomplished by powerful(More)
The remarkable lifestyle of heterocongrines has drawn the attention of many authors in the past, though no or little attention has been paid to the morphology of the tail and the head of these species. In order to examine the true nature of possible morphological specializations of the head and tail and their relation to their tail-first burrowing habit(More)
Effects of size are pervasive and affect nearly all aspects of the biology of animals and plants. Theoretical scaling models have been developed to predict the effects of size on the functioning of musculo-skeletal systems. Although numerous experimental studies have investigated the effects of size on the movements of skeletal elements during locomotion(More)
Loricariidae, or suckermouth armored catfishes, possess upper and lower jaws that are ventrally oriented and that bear teeth that touch the substrate from which algae and other food items are scraped. The ventral orientation and the highly specialized morphology of the jaws, characterized by protrusible upper jaws and left-right decoupled lower jaws, are(More)
Some species of Clariidae (air breathing catfishes) have extremely well developed (hypertrophied) jaw closing muscles that increase the maximal biting force of these species. As these enlarged jaw muscles tightly cover the suspensoria, which are firmly connected to the neurocranium, we expect diminished lateral expansions during suction for species with(More)
Newly hatched larvae of Clarias gariepinus were exposed to malathion concentrations ranging from 0.3 mg/l to 5.0 mg/l. Their development was observed through five days posthatch, i.e., the stage in which the vertebral elements are not yet present and the notochord is the only functional body axis. A significant higher proportion of C. gariepinus larvae with(More)
Bird beaks are layered structures, which contain a bony core and an outer keratin layer. The elastic moduli of this bone and keratin were obtained in a previous study. However, the mechanical role and interaction of both materials in stress dissipation during seed crushing remain unknown. In this paper, a multi-layered finite-element (FE) model of the Java(More)