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Representatives of gastropods (Gastropoda), prosobranchs (Prosobranchiata) and pulmonates (Pulmonata), appear in Czech waters. One of the best model spieces for observation in an aquarium is the great pond snail (Lymnaea stagnalis), which are pulmonate (air-breathing) snails. It has a right-coiled shell. It inhabits slow-flowing watercourses, ponds, sand pits, oxbow lakes and pools, as well as wetlands. It feeds on growths (mainly algae), dead and living parts of plants, detritus, and dead animals. This species is hermaphroditic. The eggs are laid in elongated “cocoons” about 5 cm long; the number of eggs is usually around 100. The length of embryonic development varies between 10 and 30 days depending on the temperature. The great pond snail lives 2 to 5 years. The second model species, which is well known to aquarists, is the exotic thermophilic Argentinian spike-topped apple snail (Pomacea bridgesii). It grows to a size of 5–7 cm, and lives up to 5 years, but the life span depends on the temperature in the aquarium – the higher the temperature, the shorter the life. At temperatures below 18 degrees, they are almost inactive. In addition to gill breathing, it also draws atmospheric air with a siphon (air tube), that it pushes to the water surface. The gills are partially transformed into a simple lung sac. The mouth of its shell is closed by a permanent lid (operculum). Feeding the spike-topped apple snail is very easy, as they consume a variety of food as well as feed for aquarium fish. This species is gonochoristic. Females lay eggs above the water in a cluster, up to several centimeters in size. Young snails hatch after 2 to 4 weeks. This paper provides ideas on the methods for breeding and observation, e.g., with regard to the speed of movement, food preference, and the frequency of taking in air on the surface at different water temperatures. [ABSTRACT FROM AUTHOR]

Gammarus is an amphipod crustacean genus in the family Gammaridae. The body is laterally flattened. The head bears two pairs of antennae (the first pair is longer) and three pairs of mouthparts. There are differently shaped limbs on the seven free thoracic joints. The first two pairs of limbs (gnathopods) are pincer-like and serve to grasp food. Most of the thoracic limbs bear gill projections (used for breathing) and, in females, also a projection (oostegite), which is involved in the formation of the fetal chamber (marsupium). The buttock is seven-segmented, ending in two-branched uropods. When moving in shallow water and on the ground, they push off the bottom with the help of their chest limbs and pull their bottom. The whole body lies on its side. Sometimes freshwater shrimps move along the bottom using their limbs for a certain distance and upright. Plant parts and remains of animals (e.g. oligochaetes) appear in the food. In freshwater shrimps G. roeselii and G. fossarum, the male joins the female before actual copulation. The male is larger and clings to her back. Both sexes swim together for several days. After the female undresses, copulation takes place. After copulation, the female lays eggs (8–60) in the marsupium. Our most common species is G. fossarum, found in gently flowing waters and mountain streams. It is most often found in places with a smaller current, where there is sedimentation of plant remains, or under stones, in stands of aquatic vegetation. It is demanding on the oxygen content in the water and therefore cannot be found in the littoral of stagnant waters. The article provides breeding instructions and ideas for observing freshwater shrimps in a school aquarium. The possibility of breeding the foreign freshwater shrimp Hyalella azteca is also mentioned. [ABSTRACT FROM AUTHOR]

The Pond pond slater (Asellus aquaticus) is common throughout the temperate zone, including Europe, Asia, and North America. It is found in rivers, streams, and standing waters, particularly where there are plenty of stones can be found. It hides under these stones and is a under which it hides. It is a detritivore. Pond The pond slater is relatively tolerant of a range of pollutants and has been used as an specific indicator of water quality. Asellus aquaticus can breed throughout the year, if the temperature is high enough: . they They do not breed under in cold temperatures. Maturity can be reached in only a few months under in warm summer temperatures, but maturation may take as much as two years in permanently cold water bodies of water (e.g., high-latitude or mountain waters). Females carry eggs in a brood pouch (i.e., marsupium) underneath their body. Aquarists worldwide are showing increasing interest towards the pond slater as a low-maintenance freshwater aquarium pet and tank cleaner. It is also often sold as live food for other fish. In this contribution, are presented some observations and experiments with pond slaters in school aquaria are presented. [ABSTRACT FROM AUTHOR]

Data on the occurrence, biology, and historical background of the Atlantic salmon, Salmo salar L., (Pisces, Salmoniformes) in the Elbe river basin (Europe, North Sea drainage area) with a focus on Bohemian territory (Central Europe) from the fourteenth to twentieth centuries are summarized in this paper. Historical methods of salmon fishing in Central Europe and historical legal protection of salmon in Bohemia are presented. The salmon is a model example of species which was extirpated as a result of anthropogenic changes in the landscape and rivers in some water systems. The human activities, such as stream bed regulation, dam system construction, other migration barriers, water pollution, fisheries exploitation, that led to the extirpation of Atlantic salmon in the Elbe river basin (are discussed. The last sporadic migrating native salmon were registered in the Bohemian section of the Elbe river basin in the mid twentieth century.

Within the order Neuroptera (net-winged insects), we find aquatic larvae in two families: lance lacewings (Osmylidae) and spongillaflies (Sisyridae). The giant lacewing (Osmylus fulvicephalus) is the only species of the Osmylidae in the Czech Republic. The adults are diurnal or crepuscular weak-flying insects which mostly prey on small invertebrates, supplementing their diet with some pollen. Eggs are deposited in damp places, usually near fresh water. Adults have transparent spotted wings, and short, thin antennae. They have two compound eyes, as well as three ocelli in-between. Giant lacewing larvae have peculiar mouthparts which look like a thin forceps with the ends bending outwards. The body is elongated and slender and terminates in two extensible graspers bearing tiny hooks; these are used to aid in locomotion and to grasp prey. The larvae are associated with damp, mossy habitats and are amphibious. They hunt small invertebrate prey, from which they suck the body fluids with their mouthparts. Giant lacewing larvae are best collected by picking through mosses and stones along the edges of streams. The forewings of adult spongillaflies (Sisyridae) have a span of 4-10 millimeters, and their wings are grayish or brownish, folded like a roof The sessile eggs of Sisyridae are laid singly, or in groups, on objects that overhang water. Their water larvae have spindly legs, long antennae, and flexible, threadlike mouthparts. However, the second and third instars carry seven pairs of jointed, movable tracheal gills beneath their plump abdomens. Sisyridae larvae probe sponges with their long, flexible mouthparts. They are believed to feed exclusively on freshwater sponges, and they are unique among the Neuroptera in having segmented abdominal gills that function for breathing. After feeding and development, the mature larvae swim to the shore, attach to objects close to the water, and spin double-layered cocoons within which they pupate. Rearing Sisyridae larvae in the lab can be complicated due to the difficulty of keeping their sponge host and food source alive. Larval Sisyridae can be collected via a variety of methods, including taking them by hand from sponges, using benthic samplers in lo tic habitats. This paper describes the conditions for rather short-term rearing of the larvae of lance lacewings and spongilla flies and some ideas for experiments and observations in a school aquarium. [ABSTRACT FROM AUTHOR]

Adult alderflies (Sialidae) have a body length of less than 25 mm, long filamentous antennae, and four large dark wings of which the anterior pair is slightly longer than the posterior. The females lay a vast number of eggs on grass stems near water. When the larvae are born they drop into the water or the ground nearby it and make their way into their new aquatic biome. The aquatic larvae are flat bodied and cryptic in color. Sialidae larvae are found in many habitats, ranging from small springs to large rivers and ponds. They usually occur where the substrate is soft and where dead leaves and other detritus have accumulated. Larvae may dig into the substrate to a depth of several centimeters. The larvae are active, armed with strong sharp mandibles, and breathe by means of seven pairs of abdominal branchial filaments (tracheal gills). At the end of the abdomen is located a long tapered median filament that is covered with long hair-like sensilla, which are used to detect external stimuli. Larvae crawl along the bottom; they are non-selective predators that feed on insect larvae, annelid worms, crustaceans and mollusks. Cannibalism can occur if the population density in an area is high. Pupae are found on the land in soil and moss. Alderfly pupae are exarate, meaning that the developing wings, legs, antennae and mouthparts are attached only at the base end and do not develop in a cocoon. This contribution describes the conditions for rearing larvae and some ideas for experiments and observations in a school aquarium. [ABSTRACT FROM AUTHOR]

Crayfish are aquatic freshwater crustaceans that breathe through gills. They are found in flowing and stagnant water. Most crayfish cannot tolerate polluted water. Their body consists of twenty body segments grouped into two main body parts, the cephalothorax and the abdomen. They have five pairs of walking limbs, with prominent claws on the first pair. Many species are susceptible to infections such as crayfish plague (Aphanomyces astaci). In some European countries, native species of crayfish are threatened by imported species from North America (e.g., Procambarus clarkii, Faxonius limosus, Pacifastacus leniusculus, Procambarus fallax f. virginalis), which are carriers of crayfish plague. This contribution provides instructions for keeping them in school aquaria, along with suggestions for observations and experiments. The listed non-native species are suitable for breeding in an aquarium (also the pygmy species of Cambarellus patzcuerensis, in orange or blue varieties, is popular among aquarists), because native species living in the Czech Republic are protected by law. [ABSTRACT FROM AUTHOR]

Bivalvia is a class of marine and freshwater mollusks that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. The majority are filter feeders. The gills have evolved into ctenidia, specialized organs for feeding and breathing. Most bivalves bury themselves in sediment, where they are relatively safe from predation. The shell of a bivalve is composed of calcium carbonate, and consists of two, usually similar, parts called valves. These are joined together along one edge (the hinge line) by a flexible ligament that, usually in conjunction with interlocking «teeth» on each of the valves, forms the hinge. This arrangement allows the shell to be opened and closed without the two halves detaching. The shell is typically bilaterally symmetrical, with the hinge lying in the sagittal plane. Bivalves have long been a part of the diet of coastal and riparian human populations. Oysters were cultured in ponds by the Romans, and mariculture has more recently become an important source of bivalves for food. Pearl oysters (the common name of two very different families in salt water and fresh water) are the most common source of natural pearls. The shells of bivalves are used in craftwork, and the manufacture of jewelry and buttons. Bivalves have also been used in the biocontrol of pollution. In this contribution, information about the rearing of certain species in aquaria are presented, and some observations and experiments in school aquaria are noted. [ABSTRACT FROM AUTHOR]

Leeches are segmented parasitic or predatory invertebrates within the phylum Annelida. The majority of leeches live in freshwater habitats, while some species can be found in terrestrial or marine environments. A majority of leech species are predatory, mostly preying on small invertebrates. The European medicinal leech Hirudo medicinalis is hematophagous. Leeches are protandric hermaphrodites. Their eggs are enclosed in a cocoon; members of one family, Glossiphoniidae, exhibit parental care, the eggs being brooded by the parent. Many leeches avoid light. Leeches live in damp surroundings and in general respire through their body wall. The exception to this is in the family Piscicolidae, where branching or leaf-like lateral outgrowths from the body wall form gills. Leeches move using their longitudinal and circular muscles in a modification of locomotion by peristalsis, which is self-propulsion by alternately contracting and lengthening parts of the body, seen in other annelids such as earthworms. They use their posterior and anterior suckers to enable them to progress by looping or inching along, in the manner of geometer moth caterpillars. Leeches explore their environment with head movements and body waving. Hirudinidae and Erpobdellidae can swim rapidly with up-and-down or sideways undulations of the body; the Glossiphoniidae in contrast are poor swimmers and curl up and fall to the sediment below when disturbed. In this article some observations of leeches in a school aquarium are presented. [ABSTRACT FROM AUTHOR]

Caddisflies (Trichoptera), are a group of insects with aquatic larvae and pupal stages, whereas adults are terrestrial insects. The aquatic larvae are found in a wide variety of habitats such as streams, rivers, lakes, ponds, spring seeps and temporary waters (vernal pools). The larvae of many species use silk to make protective cases, which are often strengthened with gravel, sand, twigs, bitten-off pieces of plants, bark, sticks, seeds, mollusk shells or other debris. The larval case is a tubular structure and is started soon after the egg hatches. The various reinforcements mentioned may be incorporated into its structure, the nature of the materials and design depending on the larva‘s genetic makeup; this means that caddisfly larvae can be recognized by their cases down to the family, and even genus level. As the larva grows, more material is added at the front, and the larva can turn round in the tube and trim the rear end so that it does not drag along the substrate. Caddisfly cases are open at both ends, the larvae drawing oxygenated water through the posterior end, over their gills, and pumping it out of the wider, anterior end. The larvae move around inside the tubes and this helps maintain the water current; the lower the oxygen content of the water, the more active the larvae need to be. The larvae exhibit various feeding strategies, with different species being predators, leaf shredders, algal grazers, or collectors of particles from the water column and benthos. In this contribution, some observations and experiments in school aquaria are presented. [ABSTRACT FROM AUTHOR]

The shield bug Elasmucha grisea (Insecta, Heteroptera, Acanthosomatidae) is common and easily accessible species in our country. Maternal guarding of eggs and immature offspring against enemies with typical defense behaviour can be well presented in inquiry-oriented school education focused on ethology. This behaviour is well observable with the naked eye (or using magnifying glass). There are described four basic female reactions against trespasser with respect of disturbtion intensity (see pen-and-ink drawings). Maternal care is prolonged until the third instar of offspring. More informations are presented in quoted literary sources. Proposals of some simple indoor ethological observations and experiments in school insectaria are presented. [ABSTRACT FROM AUTHOR]

This study describes the extinction reasons of the Atlantic salmon (Salmo salar) in the Elbe River (North Sea Basin, Central Europe). Poor water quality, river regulations and dam building are regarded to be the main causes of salmon extinction in this river. Historical occurrence of salmon is mentioned and last specimens registered in Germany and Bohemia (Czech Republic) are documented. After a half-century of its absence in the Elbe River restoration activities were started. Reintroduction activities are based on the international program "Lachs (Salmon) 2000," consisting of permanent releasing of fry or parr in various tributaries of the Elbe River. Experience with salmon stocking in the last decades in both of the mentioned countries are discussed. Improving the water quality and penetration of salmon migration in the Elbe River enabled salmon to return to its spawning places, but the historic population density and self-sustaining populations are not yet reached. Nevertheless, Atlantic salmon, as a well-known flagship species, plays an important role in a complex approach to the protection of running waters with the other anadromous and catadromous fishes. [ABSTRACT FROM AUTHOR]