A range of leg anomalies was detected in embryos of the Tegenaria atrica spiders exposed to alternating temperatures of 14 and 32 °C. Multiple anomalies were observed in 13 individuals. This study is based on five individuals: two individuals affected by oligomely combined, respectively, with heterosymely and polymely, one affected by polymely with heterosymely, one by complicated polymely (accompanied by the reduction in length and malformations of the distal parts of the legs), and one individual with pure polymely. Changes in the central nervous system of these five individuals were described in detail on the basis of histological sections. The changes were mainly related to the number of neuromeres. Individuals affected by polymely had additional ganglia corresponding to the number of additional appendages, whereas the absence of a leg (oligomely) was associated with the absence of a ganglion. Histological analysis showed the fusion of ganglia in the three polymelic specimens, even though additional appendages were not fused.

The diversity and longitudinal variation of zooplankton in the lower Vistula River were analyzed. Samples were taken from 40 stations located along a 272-km long section of the lower river course. During the study the unique technique of taking samples from "the same water" was used. The zooplankton community was dominated by rotifers and naupliilarval stages of copepods. The most abundant species were: Brachionus angularis, Brachionus calyciflorus and Brachionus budapestiensis. The zooplankton species diversity in the main channel of the lower Vistula River was similar to other large European rivers; however, its abundance was lower. The diversity, abundance and biomass of potamoplankton steadily decreased downstream. This could be related both to scarcity of storage zones for potamoplankton development in the river due to the extensive regulation processes, and changes in hydrological conditions of the main channel (by the straightening of riverbed) where the samples were collected.

Spider embryogenesis is affected by a range of environmental factors. Any sudden, drastic change in the environment may impair spider development, leading to various body deformities. In the present study, we analyze changes in the morphology and structure of the central nervous system of an Eratigena atrica larva, obtained in a teratological experiment in which embryos were exposed to alternating temperatures of 14 and 32°C for the first 10 days. The studied larva had three pedipalps on the right side of the prosoma (polymely), two of which were fused along their entire length (total heterosymely). In addition, there was a short, club-shaped stump between the pedipalps. Histological analysis confirmed major changes in the structure of the subesophageal ganglion, i.e., the fusion of all three ganglia of pedipalps.

This paper presents the results of research on the nervous system in individuals of Tegenaria atrica with heterosymely of walking legs, a pedipalp and the first walking leg. Temperatures alternating between 14 degrees and 32 degrees C every 12 hours were applied as a teratogenic factor in the early stage of embryogenesis. From the thus obtained specimens, histological sections were taken using the paraffin method and then stained. Analysis of the nervous system in individuals with partial heterosymely of walking legs showed no significant changes in the structure of subesophageal nervous mass. In most of the studied individuals with partial and total heterosymely of a pedipalp and walking leg no changes were observed in the relevant parts of the nervous system either, although in two cases a fusion of nerve ganglia was noted, from which the nerves branched off towards the conjoined legs.

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