Side Of Aquarium Research Articles

New techniques yield new insights on the basic biology of living microgastropods

Light traps, undisturbed sediment cores and emergence traps were used to pursue new knowledge of the biology of poorly-known microgastropods. These tools were used specifi cally to explore novel habitats, behavior and function. The most interesting discoveries include signifi cant interstitial populations of species previously considered rare, including epipsammic browsers and taxa that emerge from the sediment at night. Diel activity patterns include movement between sediment and water column, movement between sediment and marine plants, vertical migrations on marine plants, and movement between plants and plant epiphytes. Unsuspected behavioral correlates include active swimming and mass spawning aggregations and drifting and fl oating using mucus threads to launch into the water column from marine plants or the sides of aquaria. Ciliary locomotion is a convergent theme in microgastropods, with new examples from vetigastropod and neritopsine species that also use mucus threads in drifting. At the sediment-water interface, upside-down ciliary locomotion in the surface tension may be combined with feeding on the rich microbial ecosystem concentrated at the air-water interface.

Chemically mediated effects of injured prey on behavior of both prey and predators

Abstract We examined the behavioral responses of aquatic snails (prey) and two species of crayfish (predators) following exposure to chemical cues from injured snails. Snail survival rates and crayfish capture rates were compared between cued treatments and controls. Snails (Physa gyrina) responded to chemical cues by significantly increasing refuge use (i.e. moving to the waterline, floating or crawl-out behavior). Despite their responses, use of refugia did not influence survival rates. Crayfish species differed in their responses to these same chemicals. Orconectes juvenilis became more active (including increased movements across the substrate and reaching up sides of aquaria). In contrast, the activity levels of Procambarus clarkii did not significantly change. Nevertheless, P. clarkii captured snails in less time than O. juvenilis, regardless of whether injured-snail cue was present, and the presence of these cues did not significantly influence capture times for either crayfish species. This study provides strong evidence that injury-released chemical cues can elicit behavioral responses from both conspecific prey and their predators, but found no benefits of response for either prey or predators. The complex interplay of effects makes it difficult to draw simple, general insights about the benefits of the responses for either participant during a predator-prey interaction.

Modification of Antipredator Behavior of Caecidotea Intermedius by Its Parasite Acanthocephalus Dirus

The isopod Caecidotea intermedius serves as the intermediate host for the acanthocephalan Acanthocephalus dirus. C. intermedius is preyed upon by the northern creek chub, Semotilus atromaculatus, which also serves as the definitive host for A. dirus. The effects of the parasite on the antipredator behavior of C. intermedius were examined. We tested the hypothesis that behavioral changes induced in C. intermedius by the parasite are by—products of increased energy demands induced by the parasite (i.e., increased hunger). Infected and uninfected C. intermedius were placed in a divided aquarium with 0, 1, or 2 creek chubs. Leaf discs provided both a food source and a refuge from the predator. In the presence of the creek chubs, uninfected C. intermedius avoided the predator, and were found more frequently in refugia as the number of creek chubs increased. However, infected C.intermedius were associated with the side of aquarium containing the predator, and spent significantly more time out in the open away from the refuge regardless of the number of creek chubs. These data show that the antipredator behavior exhibited by C. intermedius is altered by A. dirus, and that such alterations are unlikely to be simply products of increased energy demands. Parasite—induced behavioral changes appear to increase C. intermedius' vulnerability to predation, thereby increasing the likelihood of A. dirus completing its life cycle. We find little evidence for greater foraging need as the mechanism indicating changes in antipredator behavior.

魚群は如何に誘引されるか?

Formerly, we set to project a plane net from one side of an aquarium (Fig. 1), and observed the direction in which a fish-group moves away on passing the free end of the net, after having moved along the side and the net Namely, we measured in many fish-groups the angle, φ, between the produced line of the projecting net and that direction for several values of the angle, θ, between the projecting net and the side of aquarium along which the groups had moved on. The obtained results are as follows: The value of θ differs with fish-groups for a constant value of φ, and the frequency distribution curve of θ has a normal form. The mode of φ decreases as θ increases, but the frequency at the mode increases. This relation holds only when another group does not exist near the free end, when a group moves away on passing that end. When another group exists near the free end, it attracts to some extent a group which goes on along the projecting net. In this case, the attracting effect increases as the angle, φ', between the line of sight of attracting group at the free end and the produced line of the net decreases and as the distance, s, of attracting agent from the free end decreases. A group in motion has a stronger effect than at rest. The present study was made to know how a fish-group would be attracted. The method taken in this study was the same as stated above, i.e., the frequency distribution of φ. was obtained in any case whatever an attracting agent was put near the free end of projecting net or not. An example of the distribution is given in Fig. 2. In this figure, curve I represents the distribution of control, i.e., the case where any attracting agent was not placed. Curve II is the distribution in the case where two attracting agents were placed near the end of projecting net. Curve II1 is the distribution selected in such a manner that it is similar to I and it coincides with II in the direction which deviates for from the agents. Curve represents the resulting distribution in consequence of the subtraction II1 from II. Curve thus obtained was of normal form in most cases where a single agent was placed. When two agents were placed at the same time subtending a large angle at the free end of projecting net, curve could be divided into two normal distributions II2' and II2 The two distributions may be supposed to be due to those two attracting agents. Assuming that the distribution II1 belongs to the groups which were not influenced by the agent and that the distribution to the attracted groups, we measured the strength of attracting effect of the agent in terms of the percentage of the area beneath the curve to that beneath the curve II. The strength of att ?? acting effect of various agents thus obtained, and the mode and the quartile deviation of the distributions I, II1 and (II2' and II2 separable if possible) are given in Table 1.

Cleaning sides of aquaria

Cleaning sides of aquaria Get access Notes and Queries, Volume s2-XI, Issue 269, 23 February 1861, Pages 154–155, https://doi.org/10.1093/nq/s2-XI.269.154b Published: 23 February 1861