Fig 1 - uploaded by Chee Kong Chim
Content may be subject to copyright.
![Parts of a knobby sea star. Sea stars were oriented such that the madreporite is pointing downwards in the photograph. The fi ve sectors of a sea star are demarcated by the interambulacral grooves (shown in black dotted lines). The sectors were labelled alphabetically, from A to E, in a clockwise direction starting from the left of the madreporite. (a) Primary tubercles are arranged in an imaginary circle (shown in a small white dotted circle) at the centre of the central disc. Arm tubercles are the next to develop. (b) Disc tubercles appear last and are con fi ned to the central disc (shown in large white dotted circle). (c) In fully-grown individuals, arm and disc tubercles are of similar size and are combined as secondary tubercles. [Colour on web only.]](profile/Chee-Kong-Chim/publication/235338110/figure/fig1/AS:299818174959624@1448493631806/Parts-of-a-knobby-sea-star-Sea-stars-were-oriented-such-that-the-madreporite-is-pointing.png)
Parts of a knobby sea star. Sea stars were oriented such that the madreporite is pointing downwards in the photograph. The fi ve sectors of a sea star are demarcated by the interambulacral grooves (shown in black dotted lines). The sectors were labelled alphabetically, from A to E, in a clockwise direction starting from the left of the madreporite. (a) Primary tubercles are arranged in an imaginary circle (shown in a small white dotted circle) at the centre of the central disc. Arm tubercles are the next to develop. (b) Disc tubercles appear last and are con fi ned to the central disc (shown in large white dotted circle). (c) In fully-grown individuals, arm and disc tubercles are of similar size and are combined as secondary tubercles. [Colour on web only.]
Source publication
A photo-identification method was developed to recognise individual Protoreaster nodosus, a large sea star wide- ly distributed in the Indo-Pacific region. Digital photographs of the aboral surface of P. nodosus individuals were obtained from intertidal populations in Singapore between 2002 and 2010. Each photograph was given a numer- ical code bas...
Context in source publication
Context 1
... Van Tienhoven et al., 2007), sea turtles (Reisser et al., 2008; Scho fi eld et al., 2008), birds (Burghardt et al., 2004), cetaceans (Auger-Méthé and Whitehead, 2007; Auger-Méthé et al., 2010; Beekmans et al., 2005; Mazzoil et al., 2004) and seals (Hiby et al., 2007; Mackey et al., 2007). The painted cray fi sh Panulirus versicolor (Frisch and Hobbs, 2007) and the octopus Wunderpus photogenicus (Huffard et al., 2008) are probably the only invertebrates that have been tracked using a photo-identi fi cation method. The number and arrangement of tubercles on the aboral surface of P . nodosus appear to be unique for each individual, and this could conceivably be used for photo-identi fi cation. These conspicuous attributes allow a small number of individuals to be photographed and then identi fi ed by eye. To identify a large number of individuals, however, will require a system that is able to match a large catalogue of photographs. High variability in the natural attributes between individuals of this species (Fisher, 1919; Liao and Clark, 1995) suggests that it is feasible to use photo-identi fi cation for individual recognition in a large population. While the system developed by Glynn (1982) proved useful for the recognition of A. planci individuals, most of the characters, mainly the multiple numbers of madreporites and anuses, are not applicable for P. nodosus . This study aims to develop a photo-identi fi cation method to recognise individual knobby sea stars and to examine if the natural marks selected ful fi ll the following requirements necessary for long-term studies: (1) are non-ambiguous and easily quanti fi ed, (2) have permutations suf fi ciently large to identify the maximum population size expected of this species, (3) have suf fi cient number of independent characters such that the animal can still be identi fi ed even if some natural markings have changed, (4) change at a slow rate with respect to monitoring frequency, and (5) are durable relative to the animal's lifespan. The reliability of the photo-identi fi cation method will be veri fi ed by a separate blind study. The aboral surface of each individual was “ divided ” into fi ve sectors (Fig. 1a). Each sector was demarcated by adjacent interambulacral grooves extending from the centre of the disc to the intersection of two adjacent arms. The sector at the immediate left of the madreporite when viewed from above was labelled as A, and subsequent sectors were labelled alphabetically from B to E in a clockwise direction. An arm extends from the central disc in each sector, and its condition (ARM) can be highly variable. The colouration of knobby sea stars is also highly variable — crimson, pink, light brown, beige, green, blue, grey and white (Clark, 1921; Chew, 1993; Lane and Vandenspiegel, 2003; pers. obs.). We found these shades of colour to be highly subjec- tive and thus dif fi cult to categorize. Furthermore, the same individual may appear differently in photographs under different lighting conditions. However, we found that the colouration (COL) of this species can be readily determined from its arm tips, which are either distinctly darker (Fig. 1a and c) than or of the same tone (Fig. 1b) as the rest of the arm. Knobby sea stars have numerous types of tubercles on their aboral surface. Primary tubercles (TP) are the fi rst to develop, are the largest and are located around the centre of the central disc (Fig. 1a). Arm tubercles (TA) are the next to appear, and usually along the median line of each arm (Fig. 1a and b). Disc tubercles (TD) are located on the central disc, and are smaller than the arm tubercles in growing individuals because they are the last to develop (Fig. 1b). In fully-grown sea stars, arm and disc tubercles are of similar size, and as a result, tubercles that lie close to the border of the central disc cannot be easily distinguished (Fig. 1c). To prevent such ambiguity, arm and disc tubercles are termed collectively as secondary tubercles (TS). Central tubercles (TC) are located at the centre of the central disc (Fig. 1c). Tubercles are large and well-de fi ned when fully developed. However, newly emerged tubercles may resemble pigmentation. Therefore, high-quality photographs were used to minimise mistaking pigmentations as tubercles and vice versa. For each sea star, a digital photograph of its aboral surface was obtained at a high resolution (3648 pixels × 2736 pixels) using a handheld digital camera. The body of a sea star can sometimes be contracted in such a way that another tubercle and/ or an arm may inadvertently block a tubercle from view. To have a clear pro fi le of each sea star, the tubercles were made to point upwards and arms made to rest closely on a fl at surface. Care was taken to minimise excessive contrast in the photographs by shading the animal from direct sunlight. The single madreporite of the sea star was used as a reference point to photograph the animal in a standardized orientation (Fig. 1). Each individual was then coded according to the characteristics on its aboral surface (i.e. COL, ARM, TC, TP, TD, TA and TS). The variations of these characteristics and their respective scores are listed in Table 1. Although Protoreaster nodosus normally has fi ve sectors, some individuals possess four or six sectors. Missing sectors were given an “ ARM ” score of “ 0 ” in reverse alphabetical order. For example, individuals with one missing sector (Fig. 2a) were given an “ ARM ” score of “ 0 ” for sector E. Additional sectors were designated as F, G, H, and so on. For example, individuals with six sectors (Fig. 2b) have sectors A – F. A normal arm (Fig. 2c) refers to a single arm arising from a sector with no signs of damage or deformity and is given an “ ARM ” score of “ 1 ” . A shortened arm without (Fig. 2d and e) or with (Fig. 2f) a regenerated arm tip, was given an “ ARM ” score of “ 2 ” or “ 3 ” , respectively. An arm of normal length but showing signs of regeneration (i.e. crooked arm; Fig. 2g) was given an “ ARM ” score of “ 4 ” . An arm with additional arm tip/s was given additional “ A ” score/s. For example, an arm with an additional arm tip had an “ ARM ” score of “ 11 ” . An arm with two additional arm tips had an “ ARM ” score of “ 111 ” . The order of “ ARM ” scores depends on the location of the additional arm tips, which may be found either along the arm (Fig. 2h) or at the distal end of the arm (Fig. 2i). The arm was scored fi rst, followed by the additional arm tip that was closest to the disc, and then from left to right for additional arm tips at the distal end. A sector with split arms has only one primary tubercle whereas an additional sector possesses an additional primary tubercle. Bifurcated (Fig. 2j and k) and trifurcated (Fig. 2l) arms had respective “ ARM ” scores of “ 1 + 1 ” and “ 1 + 1 + 1 ” . For each type of tubercle, the number ranged between 0 – ∞ . Central tubercles (TC) may be absent (Fig. 3a), single-pointed (Fig. 3b) or multi-pointed (Fig. 3c and d). The primary tubercles of an individual may be all single-pointed (Fig. 3b and d) or consist of a combination of single- and multi-pointed types (Fig. 3a and c). Multi-pointed tubercles were counted as separate tubercles. The interambulacral groove was usually devoid of tubercles, but in cases where a tubercle was present, it was considered to be “ shared ” between the two adjacent sectors (Fig. 3a). As a result, the adjacent sectors each had a score of 0.5 added to its number of tubercles. After all the characters were scored, the code was recorded in the following ...
Citations
... These results represent an improvement in the accuracy of previously published animal re-identification work, particularly for sea stars (Glynn, 1982). A photo recognition program and code has been developed to identify individual knobby stars (Protoreaster nodosus) by coloration and tubercles (Chim & Tan, 2012). However, this method was only applicable to a single species and required manual processing of each image into a coding system that was still not very reliable with a 23% error rate in the first test. ...
Animal re‐identification remains a challenging problem due to the cost of tagging systems and the difficulty of permanently attaching a physical marker to some animals, such as sea stars. Due to these challenges, photo identification is a good fit to solve this problem whether evaluated by humans or through machine learning. Accurate machine learning methods are an improvement over manual identification as they are capable of evaluating a large number of images automatically and recent advances have reduced the need for large training datasets.
This study aimed to create an accurate, robust, general purpose machine learning framework for individual animal re‐identification using images both from publicly available data as well as two groups of sea stars of different species under human care. Open‐source code was provided to accelerate work in this space. Images of two species of sea star ( Asterias rubens and Anthenea australiae ) were taken using a consumer‐grade smartphone camera and used as original datasets to train a machine learning model to re‐identify an individual animal using few examples. The model's performance was evaluated on these original sea star datasets which contained between 39–54 individuals and 983–1204 images, as well as using six publicly available re‐identification datasets for tigers, beef cattle noses, chimpanzee faces, zebras, giraffes and ringed seals ranging between 45–2056 individuals and 829–6770 images.
Using time aware‐splits, which are a data splitting technique ensuring that the model only sees an individual's images from a previous collection event during training to avoid information leaking, the model achieved high (>99%) individual re‐identification mean average precision for the top prediction (mAP@1) for the two species of sea stars. The re‐identification mAP@1 for the mammalian datasets was more variable, ranging from 83% to >99%. However, this model outperformed published state‐of‐the‐art re‐identification results for the publicly available datasets.
The reported approach for animal re‐identification is generalizable, with the same machine learning framework achieving good performance in two distinct species of sea stars with different physical attributes, as well as seven different mammalian species. This demonstrates that this methodology can be applied to nearly any species where individual re‐identification is required. This study presents a precise, practical, non‐invasive approach to animal re‐identification using only basic image collection methods.
... Six-legged starfish-inspired structure (6LSIS).42 . ...
Bio-inspired design is an impressive design method that improves a structure's crashworthiness performance and mechanical features. A cellular structure bio-inspired by a 6-legged starfish shape has been developed. Accordingly, this study examines the in-plane crushing behavior and crashworthiness of the 6-legged starfish-inspired structure (6LSIS). Analytical solutions were built based on the principle of energy balance to estimate the plateau stress in low-impact velocity conditions. Plateau stresses are related to high-impact velocities using a curve fitting method for a given wall's thickness. The predictions matched the numerical results. The crashworthiness performance of the 6LSISs mainly depends on wall thickness, impact velocity, and loading direction. It has been observed that an increase in wall thickness and impact velocity results in an enhancement in plateau stress ( σ pl ), specific energy absorption (SEA), and peak load (PL) in both directions. However, if the wall thickness is >0.3 mm, SEA decreases due to an increase in the structure's mass. The in-plane crushing direction ( X or Y) determines the crushing strength and deformation mode of the structure. This study illustrates that the crashworthiness of the structure in the X-direction is superior to that in the Y-direction.
... Previously, photo-identification techniques have been used for different groups of vertebrates, such as fishes (Gronell 1984;Connolly et al. 2002;Langtimm et al. 2004;Arzoumanian et al. 2005), birds (Qien et al. 1996;Sherley et al. 2010), mammals (Mizroch et al. 1990;Osterrieder et al. 2015;Zheng et al. 2016), amphibians (Forester 1977;Plȃiaşu et al. 2005;Gamble et al. 2008;Ribeiro and Rebelo 2011), and reptiles (Sheldon and Bradley 1989;Hallmen 1999;Dunbar et al. 2014), and for some invertebrates, such as octopuses (Huffard et al. 2008), starfishes (Chim and Tan 2012), crustaceans (Frisch and Hobbs 2007), and insects (Díaz-Calafat et al. 2018;Ruíz de la Hermosa et al. 2022). ...
Natural marks have increasingly been used as a tool for individual identification in capture–mark–recapture techniques. Photo-identification is a noninvasive alternative to traditional marking techniques, allowing individual recognition of species through time and space. We tested the APHIS (Automatic Photo Identification Suite) software as a software capable of identifying individuals of Hermann’s Tortoise (Testudo hermanni Gmelin, 1789) and European Pond Turtle (Emys orbicularis (Linneaus, 1758)) in different populations during capture–release sessions in the field based on plastron color patterns, since they can be used as natural marks for identification. For this individual identification, spot pattern matching (SPM) and image template matching (ITM) procedures were tested, achieving 100% success of individuals recognized in both procedures and visually verified by comparing the images. However, the ITM procedure was more efficient at recognizing recaptures than SPM because ITM allowed faster recapture verification, since most of the matches were directly placed in the first position on the candidate list. Previous studies used photo-identification on freshwater or sea turtles but never with terrestrial tortoise species. Consequently, it was corroborated that APHIS is a competent and efficient software considering photo-identification of T. hermanni and E. orbicularis, and that it can be applied to close species with similar and unique individual color patterns in their plastron.
... As a common species with ecological importance, Protoreaster nodosus has been subject to many scientific studies, especially in the Philippines, Indonesia (Nakajima et al. 2013), Japan (Pan et al. 2012), and Singapore (Chim and Tan 2012). An alien population observed in the Mediterranean Sea was described by Alvarado et al. (1986), but it did not seem to thrive. ...
... In most of the recent scientific publications (e.g., Alvarado et al. 1986, Bos et al. 2008, Chim and Tan 2012, Nakajima et al. 2013, Marsh and Fromont 2020 as well as marine life books and the World Asteroidea Database (Mah 2022), this species is uniformly described as common in the Indo-Pacific region from East Africa to New Caledonia and Japan. This description appears to be based generally on the classical Monograph of shallow-water Indo-West Pacific echinoderms (Clark and Rowe 1971), which summarizes statements from other papers to describe the distribution as including "Islands of western Indian Ocean" and "East Africa & Madagascar". ...
Demonstrating the absence of a species has always been a challenge for natural sciences, more used to documenting their presence; however, both data are of equal scientific significance. The horned sea star Protoreaster nodosus is said in the scientific literature to be present throughout the whole Indo-Pacific region, from eastern Africa to Pacific Ocean islands. However, a review of the scientific literature, along with a critical bibliographical study, citizen science surveys, web-based pictures analyses and field studies suggests that the presence of this species could instead be actually restricted to the western Pacific Ocean, from Thailand to Samoa and from Japan to New Caledonia, with no reliable record in the Indian Ocean. Such a huge and long-running mistake on a very common and conspicuous species exemplifies the importance of a critical approach of species distribution data, which appears too often based on layers of reproduction of never-reassessed data, turning hypotheses into commonly shared truth.
... The basic descriptive statistics were calculated (min, max, sum, variance, mean and standard deviation) and the normality of the distribution for each of these attributes was independently tested by the Shapiro and Wilkinson's test [55]. The variation of each To analyze the morphological variation of the cuticular pores, the nomenclature used to describe the anatomy of sea stars was incorporated [53]. In the pores of Minibiotus, it was possible to recognize a central region called a disk, from which there are extensions that vary in number, from three to six, called arms (Figure 1b-d). ...
The use and characterization of cuticular attributes for separation and description of species has been traditionally used in heterotardigrades; however, despite that eutardigrades show structures in the cuticle with this potential use, the intra and interspecific variation of these characters using multivariate analysis (e.g., PCA, CVA) had not been analyzed. In this present study, the shape and size of the star-shaped pores of four Minibiotus species were analyzed under univariate and multivariate morphometric analysis of six morphological characters. Our approach to evaluate the variation of pores indicate the presence of species-specific cuticular phenotypes among M. citlalium, M. constellatus, M. sidereus and M. pentannulatus. The morphological differences in these elements of sculpture allowed us to acknowledge their range of variation, as well as the identification of new potential characters o recognize these taxa, which are included in a taxonomic key to identify themtogether with M. eichhorni, M. pseudostellarus and M. vinciguerrae.
... Many computerassisted systems (pattern recognition or photographic matching software) have been developed that enable researchers to process large numbers of photographic images in relatively short timeframes. Thus, due to its bio o ica o istic financia and et ica advantages, PIM has been increasingly used in research studies of an array of taxa, such as insects and sea stars (Chim andTan 2012, Caci et al. 2013), sharks and rays (Tienhoven et al. 2007, Marshall andPierce 2012), marine and fres ater te eost fis es orreia et al. 2014, Dala-Corte et al. 2016, aquatic and terrestrial mammals (Kniest et al. 2010, Bolger et al. 2012, and turtles and lizards (Knox et al. 2013, Long andAzmi 2017), as well as toads and salamanders (Gamble et al. 2008, Caorsi et al. 2012. ...
Animal monitoring research involving mark-recapture techniques increasingly requires non-invasive methods of individual identification. The photographic identification method (PIM) is an excellent tool for this purpose and has been applied successfully to many taxa. However, the utility of PIM is a function of species-specific features that are judged suitable for a given target-species. Herein, the suitability of inguinal color patterns for photo identification of individuals of Pithecopus gonzagai are evaluated by comparing two widely used computer-assisted photographic matching programs (I³S and Wild.ID). Both programs accurately identified more than 70% of individuals in the top 20 potential matching photographs. Wild.ID was slightly better than I³S in matching efficiency and has a faster processing time. Thus, PIM is useful to identify individual P. gonzagai; however, before implementing the technique in animal-monitoring studies of other taxa, one must evaluate the suitability PIM for the target species and calibrate the relative efficiency of the software programs in identifying individuals.
... Worldwide the largest record of occurrences of abnormal starfishes have been reported in India, where at least 13 species have been listed: Anthenea pentagonula (Lamarck, 1816) (Maheswaran, Narendran, Yosuva & Gunalan, 2015), Asterina lorioli Koehler, 1910(James, 1999, Astropecten indicus Döderlein, 1888 (James, 1999;Prabhu & Bragadeeswaran, 2012;Chamundeeswari, Saranya, Shanker, Varadharajan, & Rajagopal, 2013), A. karankawai Lawrence, Cobb, Herrera, Durán-González & Solís-Marín, 2018 (ICMYL Unpublished data), Echinaster purpureus (Gray, 1840) (James, 1999), Goniodiscaster vallei (Koehler, 1910) (Maheswaran et al., 2015), Linckia laevigata (Linnaeus, 1758) (James, 1999), L. multifora (Lamarck, 1816) (James, 1999;Maheswaran et al., 2015), L. columbiae Gray, 1840 (Fisher, 1945), Nardoa galatheae (Lütken, 1864) (James, 1999), Pentaceraster regulus (Müller & Troschel, 1842) (James, 1999;Shanker & Vijayanand, 2014), Pisaster ochraceus (Brandt, 1835) (Fisher, 1945), and Protoreaster linckii (Blainville, 1830) (James, 1999;Chelladurai, Balakrishnan, Jayanthi, Ajeesh-Kumar, & Mohanraj, 2015;Chelladurai & Doss, 2016). Other species where abnormal ray numbers have been recorded include Protoreaster nodosus (Linnaeus, 1758), a starfish widely distributed in the Indo-Pacific region (Chim & Tan, 2012) and Archaster angulatus Müller & Troschel, 1842 from the Indian Ocean and western Pacific (Keesing, 2017). ...
... Arm number abnormalities are relatively common in the family Oreasteridae. Other studies have reported similar conditions for the congener P. regulus, a common starfish from the Western Central Pacific (James, 1999;Shanker & Vijayanand, 2014), P. linckii, widely distributed in the Indian Ocean (James, 1999;Chelladurai et al., 2015;Chelladurai & Doss, 2016), and P. nodosus, from the Indo-Pacific region (Chim & Tan, 2012). Abnormal arm number have been attributed to several causes like injury, regeneration errors, malnutrition, congenital issues, or damages in the metamorphosis process (Moore, 1974;Hotchkiss, 1979;Watts, Scheibling, Marsh, & McClintock, 1983). ...
Introduction:
The Panamic Cushion Star Pentaceraster cumingi is widely distributed along the Tropical Eastern Pacific. This species strictly produces only five arms, but sometimes, this number varies or show another kind of abnormality.
Objective:
We aimed to evaluate the population size structure and abnormalities occurrence in the radial pattern of P. cumingi in Bahía Chamela, Jalisco, Mexico.
Methods:
The population was monitored along four years (2016-2019), in two seasonal periods (warm and cold). During fieldwork, a random sample of individuals was collected. Every starfish was measured, weighted, and evaluated to identify any abnormality on its radial pattern.
Results:
The highest density of P. cumingi was found in October 2019 (2.03 ± 0.05 ind/m⁻²), the lower in March 2017 (0.66 ± 0.13 ind/m⁻²). A total of 849 individuals were collected. For 5-armed starfishes, the average length was 123.8 ± 15.2 mm and the average weight of 326.0 ± 62.4 g. The most frequent length classes ranged from 110 to 120 mm. Of the total of individuals sampled 0.82 % had four arms, 1.06 % six, and 1.41 % had one bifurcated arm.
Conclusions:
There were differences in the population density and size structure of P. cumingi between seasons. The main causes of abnormalities in the starfish could be due to the changes that occur during larval metamorphosis or by an abnormal regeneration of the arms after a predation attempt.
... However, only a few studies have applied PIM to invertebrates. So far, some of these unusual studies have been performed on octopuses (Huffard et al., 2008), starfish (Chim and Tan, 2012), sea cucumbers (Raj, 1998) or crustaceans (Frisch and Hobbs, 2007). Furthermore, among invertebrates, even fewer studies have been carried out using insects. ...
Photographic identification methods are of highly importance when it comes to reduce the animal's stress, pain and possible injuries during or after marking techniques and thus to increase the reliability of demographic parameter estimates. There is plenty of software available for photo-identification, allowing individual identification in capture-mark-recapture (CMR) methods using body patterns, spots and marks unique to each individual. However, these non-invasive methods have hardly ever been used with arthropods. In this study, APHIS (Automated PHoto Identification Suite) has been assessed as a software capable of identifying individuals in different samplings during catch-and-release sessions with dead specimens under laboratory conditions. For this individual identification, SPM (Spot Pattern Matching) and ITM (Image Template Matching) procedures were tested; achieving a success of 100% and 95.35%, respectively. In SPM, the software itself matched the specimens almost automatically in half of the cases. However, it resulted more time-consuming than ITM during the pre-processing of images. On the other hand, ITM saves time during this step and still is able to detect recaptures accurately, yet more time may be needed when selecting the recaptures from the candidate list. Thus, it can be attested that APHIS is a competent and efficient software regarding photo-identification of Rhynchophorus ferrugineus and species with similar and unique individual colour patterns in their pronotum.
... Five to ten tube feet were collected from 80 individuals of Protoreaster nodosus from five locations in Singapore ('north': Pulau Sekudu, Chek Jawa and Beting Bronok; 'south': Cyrene reefs and Pulau Semakau; figure 1) from January to July 2013, preserved in molecular grade ethanol and stored at −20°C. Photo-identification vouchers of the aboral surface of individuals [23] were taken prior to release of the animals, to prevent repeat genetic sampling of the same individual. [10] analysed in this study (numbered black circles). ...
The Coral Triangle is widely considered the most important centre of marine biodiversity in Asia while areas on its periphery such as the South China Sea, have received much less interest. Here, we demonstrate that a small population of the knobbly sea star Protoreaster nodosus in Singapore has similarly high levels of genetic diversity as comparable Indonesian populations from the Coral Triangle. The high genetic diversity of this population is remarkable because it is maintained despite decades of continued anthropogenic disturbance. We postulate that it is probably due to broadcast spawning which is likely to maintain high levels of population connectivity. To test this, we analysed 6140 genome-wide single nucleotide polymorphism (SNP) loci for Singapore's populations and demonstrate a pattern of near panmixia. We here document a second case of high genetic diversity and low genetic structure for a broadcast spawner in Singapore, which suggests that such species have high resilience against ant
... Knox et al., 2013;Sreekar et al., 2013) and even invertebrates (e.g. Chim & Tan, 2012;Caci et al., 2013). Photo-identification has been extensively applied for studying marine mammals (e.g. ...
... For example, Caorsi et al. (2012) found 99.4% of correct matches in naked-eye photo-identification of an anuran species based on ventral color pattern, 90.9% using computer-assisted photo-identification and 95.3% using toe-clipping method. Furthermore, our results are comparable with Chim & Tan (2012) study, which found respectively 87% and 100% of correct matches for computer-assisted and naked-eye photo evaluations of a sea star species based on tubercle patterns. Our results therefore indicate that photo-identification is a suitable method for individual identification in R. aequalicuspis. ...
Photo-identification allows individual recognition of animal species based on natural marks, being an alternative to other more stressful artificial tagging/marking techniques. An increasing number of studies with different animal groups has shown that photo-identification can successfully be used in several situations, but its feasibility to study freshwater fishes is yet to be explored. We demonstrate the potential use of photo-identification for intraspecific recognition of individuals in the stream-dwelling loricariid Rineloricaria aequalicuspis . We tested photo-identification in laboratory and field conditions based on the interindividual variability in abdominal bony plates. Our test yielded high correct matches in both laboratory (100%) and field conditions (> 97%), comparable to other reliable techniques and to studies that successfully used photo-identification in other animals. In field conditions, the number of correct matches did not differ statistically between computer-assisted and naked-eye identification. However, the average time expended to conclude computer-assisted photo evaluations was about half of the time expended to conclude naked-eye evaluations. This result may be exacerbated when using database with large number of images. Our results indicate that photo-identification can be a feasible alternative technique to study freshwater fish species, allowing for a wider use of mark-recapture in ecological and behavioral studies.
