A remarkable, precisely timed release of hyperglycemic hormone from endocrine cells in the gut is associated with ecdysis in the crab Carcinus maenas

In this article, an attempt is made to review the presently known, completely identified crustacean neuropeptides with regard to structure, function and distribution. Probably the most important progress has been made in the elucidation of a novel family of large peptides from the X-organ-sinus gland system which includes crustacean hyperglycemic hormone (CHH), putative molt-inhibiting hormone (MIH) and vitellogenesis (= gonad)-inhibiting hormone (VIH). These peptides have so far only been found in crustaceans. Renewed interest in the neurohemal pericardial organs has led to the identification of a number of cardioactive/myotropic neuropeptides, some of them unique to crustaceans. Important contributions have been made by immunocytochemical mapping of peptidergic neurons in the nervous system, which has provided evidence for a multiple role of several neuropeptides as neurohormones on the one hand and as local transmitters or modulators on the other. This has been corroborated by physiological studies. The long-known chromatophore-regulating hormones, red pigment concentrating hormone (RPCH) and pigment-dispending hormone (PDH), have been placed in a broader perspective by the demonstration of an additional role as local neuromodulators. The scope of crustacean neuropeptide research has thus been broadened considerably during the last years. Show more

Thermoregulation of the thorax allows endothermic insects to achieve power outputs during flight that are among the highest in the animal kingdom. Flying endothermic insects, including the honeybee Apis mellifera, are believed to thermoregulate almost exclusively by varying heat loss. Here it is shown that a rise in air temperature from 20 degrees to 40 degrees C causes large decreases in metabolic heat production and wing-beat frequency in honeybees during hovering, agitated, or loaded flight. Thus, variation in heat production may be the primary mechanism for achieving thermal stability in flying honeybees, and this mechanism may occur commonly in endothermic insects. Show more