Larvae aquatic animals

Ammonia is also the major nitrogenous end product in some of the simpler aquatic and marine animal forms, such as protozoa, nematodes, and even bony fishes, aquatic amphibia, and amphibian larvae. Such animals are called am-monotelic. But in many animals, NH3 is toxic, and its removal by simple diffusion is difficult. Thus, in terrestrial snails and amphibia, as well as in other animals living in environments in which water is limited, urea is the principal end product (fig. 22.6). Urea formation also helps to maintain osmotic balance with seawater in cartilagenous fishes. In such animals, most of the urea secreted by the kidney glomerulus is reabsorbed by the tubules. Indeed, the amount of nitrogen excreted by the kidneys of fishes is small com-... 

Morse, D. E., Tegner, M., Duncan, H., Hooker, N., Trevelyan, G., and Cameron, A., Induction of settling and metamorphosis of planktonic molluscan (Haliotis) larvae. Ill Signalling by metabolites of intact algae is dependent on contact, in Chemical Signals in Vertebrate and Aquatic Animals, Miiller-Schwarze, D. and Silverstein, R. M., Eds., Plenum Press, New York, 1980, 67. 

Small multicellular organisms are sensitive to very low pressures. The swimming activity of larvae of tadpoles can be reduced by 2.5 % ethanol in the medium. The activity can be restored by pressures up to 28 MPa [22]. Maedonald and Fraser [23] reported effects by pressures of 20 kPa or less on aquatic animals at the level of growth and or metabolism. The authors concluded that cells are able to respond to micropressures also through mechanical processes. 

SANDIER p A, ziEUNSKi p B and CASTRO w E (1974) A simple airlift-operated tank for closed-system culture of decapod crustacean larvae and other small aquatic animals , Helgol W s Meer, 26,82-87. 

Intraspecific chemical signaling could be involved in a wide range of interactions where marine and aquatic animals search for mates, avoid competing conspe-cifics, need to synchronize release of gametes or larvae, or identify near versus... 

Acid rain falling into streams, rivers and lakes will lower the pH of the water. Many aquatic animals are very sensitive to changes in pH. Many insect larvae cannot survive even slight increases in acidity. Other animals higher up the food chain may be more resistant, but their numbers will decrease as their food source dies off. 

Bacteria as biocontrol agents for aquatic animal larvae... 

The photo synthetic aquatic biomass comprises cyanobacteria (formerly called blue-green algae), planktonic, filamentous and macrophytic algae, and vascular macrophytes. The net productivity of the floodwater depends on the level of primary production by the photosynthetic biomass versus its consumption by grazing animals, particularly cladocerans, copepods, ostracods, insect larvae and molluscs. Their role will change as the canopy develops and at a leaf area index of about 6-7 there will be no more photosynthetically active radiation available to them. 

Ammonotelic animals most aquatic vertebrates, such as bony fishes and the larvae of amphibia... 

Metamorphosis has also been extensively studied in amphibians, a class of vertebrates which includes frogs, toads, and salamanders. Amphibian means dual (amphi ) life form (-bian) and refers to the typical life history of these animals, in which an aquatic larva metamorphoses into a terrestrial adult. The reptiles, such as turtles, lizards, and snakes, is another class of vertebrates whose species superficially resemble adult amphibians, but do not undergo metamorphosis. 

Total biomass of fresh-water animals is formed mostly by molluscs, aquatic insects (larvae), bark beetles and fish. Less important from the aspect of weight, but often ecologically significant are the Annelida, whirligig beetles, and other worms [1, 2]. 

Nickel concentrations are comparatively elevated in aquatic plants and animals in the vicinity of nickel smelters, nickel-cadmium battery plants, electroplating plants, sewage outfalls, coal ash disposal basins, and heavily populated areas. For example, at Sudbury, Ontario, mean nickel concentrations, in mg/kg DW, were 22.0 in larvae of aquatic insects, 25.0 in zooplankton, and 290.0 in aquatic weeds maximum concentrations reported were 921.0 mg/kg DW in gut of crayfish (Cambarus bartoni) and... 

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