scholarly journals Short range hunters: Exploring the function and constraints of water shooting in dwarf gouramis

2021 ◽  
Author(s):  
Nick Jones ◽  
Barbara C. Klump ◽  
Teresa M. Abaurrea ◽  
Sophie Harrower ◽  
Clare Marr ◽  
...  
Keyword(s):  
Sex Differences ◽  
Convergent Evolution ◽  
Water Surface ◽  
Short Range ◽  
Target Height ◽  
Live Prey ◽  
Foraging Ability ◽  
Single Genus ◽  
Series Of Experiments ◽  
Novel Target

Ballistic predation is a rare foraging adaptation: in fishes, most attention has focused on a single genus, the archerfish, known to manipulate water to shoot down prey above the water surface. However, several gourami species also exhibit apparently similar ‘shooting’ behaviour, spitting water up to 5cm above the surface. In a series of experiments, we explored the shooting behaviour and aspects of its significance as a foraging ability in the dwarf gourami (Trichogaster lalius). We investigated sex differences in shooting abilities as gourami shooting may be related to the sex-specific bubble nest manufacture - where males mix air and water at the surface to form bubbles - finding that actually both sexes are equally able to shoot and learn to shoot a novel target. In a second experiment, we presented untrained gouramis with opportunities to shoot at live prey and found they successfully shot down both fruit flies and crickets. Finally, we explored the effect of target height on shooting performance to establish potential constraints of shooting as a foraging ability. The frequency of attempted shots and success of hitting targets decreased with height while latency to shoot increased. We also observed that repeatable individual differences account for variation in these measures of shooting performance. Together our results provide evidence that gourami shooting has a foraging function analogous to that of archerfish. Gourami shooting may serve as an example of convergent evolution and provide opportunities for comparative studies into the, yet unexplored, ecology and evolution of shooting in fishes.

scholarly journals A Novel Target-Height Estimation Approach Using Radar-Wave Multipath Propagation for Automotive Applications

2017 ◽  
Vol 15 ◽  
pp. 61-67
Author(s):  
Amir Laribi ◽  
Markus Hahn ◽  
Jürgen Dickmann ◽  
Christian Waldschmidt
Keyword(s):  
Continuous Wave ◽  
Multipath Propagation ◽  
Estimation Error ◽  
Propagation Model ◽  
Target Range ◽  
Target Height ◽  
Height Estimation ◽  
Range Resolution ◽  
Novel Target ◽  
Radar Wave

Abstract. This paper introduces a novel target height estimation approach using a Frequency Modulation Continuous Wave (FMCW) automotive radar. The presented algorithm takes advantage of radar wave multipath propagation to measure the height of objects in the vehicle surroundings. A multipath propagation model is presented first, then a target height is formulated using geometry, based on the presented propagation model. It is then shown from Sensor-Target geometry that height estimation of targets is highly dependent on the radar range resolution, target range and target height. The high resolution algorithm RELAX is discussed and applied to collected raw data to enhance the radar range resolution capability. This enables a more accurate height estimation especially for low targets. Finally, the results of a measurement campaign using corner reflectors at different heights are discussed to show that target heights can be very accurately resolved by the proposed algorithm and that for low targets an average mean height estimation error of 0.03 m has been achieved by the proposed height finding algorithm.

Biologically inspired collective comparisons by robotic swarms

2011 ◽  
Vol 30 (5) ◽  
pp. 524-535 ◽  
Author(s):  
Chris A C Parker ◽  
Hong Zhang
Keyword(s):  
Theoretical Analysis ◽  
Short Range ◽  
Social Insect ◽  
Peer To Peer ◽  
Biologically Inspired ◽  
Peer Communication ◽  
Robotic Swarms ◽  
Robotic Swarm ◽  
Series Of Experiments ◽  
Comparison Strategy

Intelligent entities must often make decisions by comparing several candidate alternatives and selecting the best one. This is just as true for autonomous swarms as it is for solitary robots, but to date there has been little work to propose efficient comparison behaviors for autonomous robotic swarms that are not tied to specific environments. In this work, we examine an elegant collective comparison strategy that is used by at least three different species of social insect and adapt it for artificial systems. The behavior is particularly attractive for robotic implementations because it relies only on short range explicit peer-to-peer communication, eliminating the need for chemical trails or other forms of stigmergy. The proposed comparison strategy is proven to converge, and a series of experiments using real robots with noisy sensors is presented that validates our theoretical analysis. Using the proposed behavior, a robotic swarm is able to compare alternatives collectively more accurately than its member robots would be able to individually.

On Water-finding and Oviposition by captive Mosquitoes

1942 ◽  
Vol 32 (4) ◽  
pp. 279-301 ◽  
Author(s):  
John S. Kennedy
Keyword(s):  
Aedes Aegypti ◽  
Water Vapour ◽  
Culex Pipiens ◽  
Water Surface ◽  
Short Range ◽  
Diurnal Changes ◽  
Hovering Flight ◽  
Surface Contact ◽  
Culex Pipiens Molestus ◽  
Geotactic Response

1. The behaviour of Anopheles labranchiae atroparvus, Culex pipiens molestus and Aëdes aegypti has been studied before and during oviposition.2. Anopheles and Culex when ready to lay make repeated descents to the ground and fly about with a skimming-hopping movement, while Aëdes flies about generally, at all heights.3. On encountering water Anopheles breaks into a hovering flight, laying its eggs during this “oviposition dance” or while settled on the water. Culex stops “dead” on the water and lays its eggs settled there, as does Aëdes but with some fidgeting about. After encountering water mosquitoes may leave it again, but fly about the floor more steadily and persistently than before.4. Among the factors which stimulate mosquitoes after they have arrived directly over a water surface, contact with the surface is essential for actual oviposition by Culex and Aëdes, and almost so for Anopheles. Good pre-ovipository responses may be induced by water vapour alone and by the reflection from the surface, although how this latter stimulus acts is not clear. A dark appearance, especially if the surroundings are relatively light, facilitates these responses.5. Direct attraction of the mosquitoes over the short range available in a cage was only induced by a contrastingly dark appearance, but Anopheles and Culex are aided in water finding by diurnal changes, correlated with light and activity changes, in the sense of their geotactic response.

The evaporation of water from soil. II.: Influence of soil type and manurial treatment

1921 ◽  
Vol 11 (4) ◽  
pp. 432-440 ◽  
Author(s):  
Bernard A. Keen
Keyword(s):  
Organic Material ◽  
Water Surface ◽  
Farmyard Manure ◽  
Free Water ◽  
Clay Content ◽  
Soil Samples ◽  
The Other ◽  
Moisture Equivalent ◽  
Series Of Experiments ◽  
Manurial Treatment

Further experiments have been done on the evaporation of water from soil, using the same apparatus and technique as described in an earlier paper. The present series of experiments was designed to investigate the effect of clay content and manurial treatment on the evaporation. Two soils have been used, one containing only 6% clay and the other 15%, and from each soil samples were taken from plots which had received (a) no manure, (b) artificial manure, (c) farmyard manure. The rate at which the soils lost water over concentrated sulphuric acid and at a constant temperature, was found to depend firstly on the amount of clay present, and secondly on the amount of organic material in the soil. The differences due to content of organic material were more obvious in the soil containing the larger amount of clay; the farmyard manure plot lost water at the slowest rate, and the unmanured plot occupied an intermediate position. In the sandy soil the differences in evaporation due to manuring were small.There is evidence that the moisture equivalent of these soils measures the percentage of water at which the evaporation is first directly affected by the soil particles, and that at percentages of water in excess of the moisture equivalent evaporation is taking place substantially from a free water surface.

Experimental Study on the Fluid Mud Transportation Under Currents with Fluctuating Water Surface

2016 ◽  
Vol 11 (5) ◽  
pp. 982-988
Author(s):  
Chunrong Liu ◽  
◽  
Wenyu Yang ◽  
Bo Wu ◽  
Huhe Aode ◽  
...  
Keyword(s):  
Experimental Study ◽  
Shear Stress ◽  
Cross Section ◽  
Water Surface ◽  
Bed Shear Stress ◽  
Fluid Mud ◽  
Water Currents ◽  
Series Of Experiments ◽  
Surface Fluctuation ◽  
Over Time

A series of experiments conducted to study fluid mud movement in currents with a fluctuating water surface involved measuring fluid mud yield stress, bed shear stress, and water surface fluctuation. To observe fluid mud movement, we dyed a sheet of fluid mud in the water flume cross-section red. We then calculated the fluid mud transportation velocity based on mud sheet displacement over time. Experiments showed that water surface fluctuation plays an important role in fluid mud movement. Under conditions of water surface fluctuation, we were able to observe fluid mud oscillation in the case that the interface of the water and fluid mud is clear. After several oscillation cycles, fluid mud is transported downstream by water currents.

scholarly journals Role of Kisspeptin and NKB in Puberty in Nonhuman Primates: Sex Differences

2019 ◽  
Vol 37 (02) ◽  
pp. 047-055 ◽  
Author(s):  
James P. Garcia ◽  
Kim L. Keen ◽  
Stephanie B. Seminara ◽  
Ei Terasawa
Keyword(s):  
Sex Differences ◽  
Nonhuman Primates ◽  
Reproductive Function ◽  
Contributing Factors ◽  
Gnrh Release ◽  
Pubertal Stages ◽  
Series Of Experiments ◽  
Males And Females ◽  
Flexible Mechanisms

AbstractTo understand the roles of kisspeptin and neurokinin B (NKB) in puberty and sex differences in their involvement, we conducted a series of experiments measuring the release of gonadotropin-releasing hormone (GnRH) and kisspeptin in the median eminence of the hypothalamus in male and female monkeys throughout sexual development. Results indicate that kisspeptin-10 and the NKB agonist, senktide, stimulated GnRH release in males and females at the prepubertal and pubertal stages, but females are much more sensitive to kisspeptin signaling than males. Moreover, throughout the progress of puberty, major remodeling of kisspeptin and NKB signaling pathways for the regulation of GnRH release takes place. In females during puberty, reciprocal pathways (i.e., kisspeptin signaling mediated through NKB neurons and NKB signaling mediated through kisspeptin neurons) are established, to provide powerful and flexible mechanisms for GnRH neurosecretory activity necessary for complex female reproductive function in adulthood. By contrast, during puberty in males, reciprocal pathways are consolidated to a simpler kisspeptin-dominant signaling pathway. Nevertheless, in primates, both kisspeptin and NKB signaling are contributing factors for the pubertal increase in GnRH release, rather than initiating puberty.

Birds Underwater: A Paucity of Information

2017 ◽  
Author(s):  
Graham R. Martin
Keyword(s):  
Visual Information ◽  
Escape Response ◽  
Spectral Properties ◽  
Water Surface ◽  
Short Range ◽  
Radical Change ◽  
Ambient Light ◽  
Visual Resolution ◽  
Light Levels ◽  
Touch Sensitivity

Entering beneath the water surface produces a radical change in perceptual challenges. The eye is no longer able to focus adequately and, with increasing depth, light levels decrease and the spectral properties of ambient light narrows with the result that visual resolution decreases rapidly and colour cues are lost. Diving to depth is rapid which means that perceptual challenges change constantly. This results in a paucity of visual information and olfaction and hearing cannot be used to complement this loss. Amphibious foragers must rely upon minimal cues and very specialized foraging behaviours; some ducks may forage for sessile prey using touch sensitivity in the bill, cormorants use a technique in which they trigger an escape response from a fish which they catch at very short range, while penguins and auks may rely upon minimal cues from photophores on fish and random encounters with prey.

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