The distribution of North American invasive crayfish species Pacifastacus leniusculus has rapidly extended to lakes and rivers in Hokkaido, Japan. In 2006, P. leniusculus was designated as a regulated living organism under the Invasive Alien Species Act by the Ministry of Environment of Japan because it may have negative effects on native animals, including the endangered Japanese native crayfish Cambaroides japonicus. The establishment of P. leniuculus is considered to be the result of introduction by humans, including children. Thus, children also need to be educated about the impacts of P. leniusculus, as well as other invasive species, on native ecosystems. However, our present school education has an inadequate educational curriculum on invasive species. In this study, we made a questionnaire survey of elementary students in the fourth grade (n=141) to clarify knowledge by children of P. leniusculus. We also made a questionnaire survey of a wide range of residents (n=100; 70% adults) living in an area around a river in Obihiro City, Hokkaido, where P. leniuculus is established, to compare the knowledge of P. leniusculus between children and adults. Both children and adults had an inadequate knowledge of P. leniusculus and often confused P. leniusculus with the native C. japonicus and the invasive crayfish Procambarus clarkii. The results showed that many children and adults release P. leniusculus into unspecific rivers, lakes or marshes after they stop rearing P. leniusculus in their homes, suggesting that such releasing of P. leniusculus by children and adults causes the continuing new establishments of P. leniusculus in Hokkaido. Thus, we need to educate children, as well as adults, using accurate knowledge of invasive crayfish in biological and environmental education in schools and communities.
In this paper, we propose a series of comparative anatomical and physiological experiments on the respiration of goldfish and larval bullfrogs to teach the evolution of the respiratory systems in vertebrates. The anatomies of the larval bullfrogs in different stages showed that their lungs develop even more in the earlier stages than the metamorphoses, and that the bloodstreams in the capillaries run on the bulla of the lungs. The experiments under anaerobic conditions showed that larval bullfrogs could respire the air by the lungs in anaerobic water where goldfish could hardly respire, and that the frequency of the lung ventilation of larval bullfrogs temporarily increased under anaerobic atmospheric gases while it decreased under aerobic atmospheres. The experiment showed that the oxygen uptake of larval bullfrogs is distributed equally among the skin, the gills and the lungs in their early stage. According to the development of the metamorphic stage of larval bullfrogs, the oxygen uptake increased in ratio with the lungs while it decreased with the gills. The anatomy of the swim bladder of goldfish confirmed that there are no blood vesicles on the bladder, and a fine pneumatic duct connects the bladder and the pharynx. We recommend this series of anatomies and experiments for overcoming the misconceptions about the respiration of tadpoles and teaching students the origin of the lungs of vertebrates and the evolution into the swim bladders of divergent teleost.
A method for the observation of cell division using acetic dahlia solution was introduced to lower secondary school science classes. Onion seeds with about 10 mm of the germinated portion could be stored in a refrigerator for at least one week in good condition for observing cell division. A staining temperature at 35°C resulted in a ten minute reduction compared to that of room temperature. These findings are useful for preparing specimens and observing dividing cells under a microscope in a limited time of lesson (50 min) in lower secondary schools.