## 1 Introduction  
Unlike plants, animals can move in a short time, which is a distinctive and defining characteristic of animals. Animal movements are controlled by the brain or nerve cells; however, genes, chemicals, the environment, and aging also affect movement. For example, short- and long-lived _Caenorhabditis elegans_ mutant strains carrying mutant _daf-2_, _daf-16_, _age-1_, _tax-4_, or _lite-1_ genes displayed different locomotor activities during aging [1]. Chemical pollutants affect individuals' anxiety, risk perception, hyperactivity, lower activity, and cognition, resulting in changes in movement and social behavior, such as social networks, response times to group action, group cohesion, polarization, and social competence [2]. Chemicals, such as pictotoxin and nicotine, in response to light, changed the movement of zebrafish (_Danio rerio_) and also altered their shoaling behavior [3]. In a study on the effect of 20 different nanoparticles on the phenotype of _C. elegans_, the average movement speed of animals varied according to the type of nanoparticle [4]. Small animals, such as zebrafish, _C. elegans_, and _Daphnia_ can be tested in a small space, making them suitable for high-throughput studies [5; 6; 7]. Multiwell plates make it easy to track changes in the movement of individual animals per well. Because it is difficult for humans to manually quantify the movements of individual animals over time, it is necessary to use image analysis software to analyze the images captured during the experiment. For example, more than 6500 fish have been recorded using multiwell plates to detect hearing defects in zebrafish [8]. The image analysis software automatically detected animals that did not respond to tone bursts by generating differential binary images from images before and after tone bursts. In another study, videos were taken after exposure of zebrafish in multiwell plates to each of 5648 compounds of psychoactive drugs. The videos were then analyzed to extract behavioral parameters, such as rest latency, rest bouts, and waking activity from locomotor activity over time. Hierarchical clustering of compounds using multiple parameter values revealed previously unknown psychoactive drugs and their action mechanisms [9]. To perform such studies, it is essential to develop an easy and reliable automatic image analysis software. Various software have been proven to be useful in animal tracking [10; 11; 12; 13; 14; 15; 16; 17; 18; 19]. For example, EthoVision [13] (Noldus Information Technology, Wageningen, The Netherlands) can analyze the movement of various animals using a dedicated imaging system. To detect an animal, the raw image is gray-scaled and then binarized, or the area with change is tracked from a subtracted image obtained from two images. Additionally, an animal with a specific color can be tracked from a hue saturation-intensity (HSI) color channel image. idTracker, which was developed using MATLAB (The MathWorks Inc., Natick, MA, USA), was able to obtain the correct trajectories of each animal with a high accuracy of 99.7%, even when animals crossed each other, using fingerprints of individual animals extracted from images [14]. The Lifespan Machine analyzes timelapse images taken regularly on a flatbed scanner [15]. The software calculates a motion score based on the change in posture of an animal, determines the animal's point of death, and then measures its lifespan. Janelia Automatic Animal Behavior Annotator (JAABA) can annotate various behaviors of animals using a classifier trained through machine learning using video and trajectory information of the animal [16]. wrMTrck [17] and AnimalTracker [18] are ImageJ-based animal tracking software that can analyze the travel length, average speed, trajectory, and other parameters. Tracktor is another locomotion analysis software that uses the OpenCV library [19].