The Research About Morphometric Characteristics on Leptograpsus Crabs

doi:10.21203/rs.3.rs-3082209/v1

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The Research About Morphometric Characteristics on Leptograpsus Crabs

https://doi.org/10.21203/rs.3.rs-3082209/v1

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The process of this research includes the morphometric characteristics of 200 Leptograpsus crabs emphasized in the data set handled by Campbell and Mahon. To determine the meat composition, differences such as gender, color, and other variables were investigated by considering the frontal lobe, posterior width, shell width, body depth, and shell lengths. As a consequence of the study, it was finalized that the meat ratios of Leptograpsus crabs, which were previously separated into two different colors, differ according to their colors. Simultaneously, when the nutritional ratios of crabs with high protein are concerned, it is seen that the ratio of midline length to the maximum width of orange crabs is higher. Moreover, it was supposed that the ratio of posterior region width to anterior region width of blue crabs was higher than that of orange crabs.

Leptograpsus Crabs

Meat Composition

Morphometric Characteristics

Leptotgrapsus [3], has been called as the rock crab, is known to live in the western parts of South America, on the Pacific islands, and on the coast of Australia [2].

The consumption of leptotgrapsus crabs is evolving increasingly pervasive when it is compared to other crabs in the world. This crab species, which Campbell and Mahon [1] discussed in their studies, consists of two different species, blue and orange. In the scientific literature, until the analysis of Campbell and Mahon in 1974, crabs of this color is known as morphs of Leptotgrapsus [4].

Researchs are assumed on the edible meat quality of crabs and it is known that they are being consumed as an essential food source in developed countries. Besides the high quality of the meat of crabs, crab waste and shells are also used.

It is used for feeding many animals, especially poultry and fish thanks to the amount of minerals and nutrients that waste meat has. Crab shells are used in industries such as textiles and cosmetics [7].

Obviously, there has not been extensive analysis of Leptotgrapsus crabs in the scientific literature since the study of Campbell and Mahon. The main purpose of this study was specified to examine the morphometric characteristics of Leptotgrapsus crabs.

The taxonomy of Leptotgrapsus crabs was assembled by Milne-Edwards [6] as follows;

Filum

Arthropoda

Classis

Crustacea

Subclassis

Malacostraca

Ordo

Decapoda

Supersection

Pleocyemata

Section

Brachyura

Familya

Grapsidae

Genus

Leptograpsus

Species

L. variegatus

A total of 200 data from Leptograpsus L. variegatus crabs, 100 orange, 100 blue, and 50 from each sex, were examined in this research. The data set was acquired by Mahon [5]. The data in the data set was consisting of the maximum width of the shell, the midline length of the shell, the posterior region of the shell, the anterior width of the shell, the maximum width of the shell, and the body depth. These measurements were obtained with precision scales up to 0.1 mm.

According to Fig. 1, FL determines for anterior region width, RW stands for posterior region width, CL stands for midline length, and CW shows for maximum width.

The examination was performed on data obtained from 200 crabs gathered from the Fremantle region. Fundamental statistical analyzes were estimated founded on the collected data. In addition, the relations between them were defined according to color and gender.

A number of calculations were made on the data set to determine the meat composition. Evaluations will be done on the values obtained as a result of this calculation.

The data acquired in this study includes a total of 200 crabs. This data set consists of 50 orange males, 50 orange females, 50 blue males, and 50 blue females.

Table 1

Statistics by Color
		Average	Std. Deviation	Variance
Frontal Lobe	Blue	14.056	3.019	9.114
Frontal Lobe	Orange	17.11	3.275	10.726
Back Width	Blue	11.928	2.279	5.194
Back Width	Orange	13.549	2.605	6.786
Shell Lenght	Blue	30.058	6.903	47.651
Shell Lenght	Orange	34.153	6.764	45.752
Shell Width	Blue	34.717	7.866	61.874
Shell Width	Orange	38.112	7.541	56.867
Body Depth	Blue	12.583	3.068	9.413
Body Depth	Orange	15.478	3.151	9.929

Table 2

Statistics by Gender
		Average	Std. Deviation	Variance
Frontal Lobe	Male	15.734	3.463	11.992
Frontal Lobe	Female	15.432	3.538	12.517
Back Width	Male	11.99	2.16	4.666
Back Width	Female	13.487	2.741	7.513
Shell Lenght	Male	32.851	7.471	55.816
Shell Lenght	Female	31.36	6.703	44.930
Shell Width	Male	36.999	8.33	69.389
Shell Width	Female	35.83	7.381	54.479
Body Depth	Male	14.337	3.494	12.208
Body Depth	Female	13.724	3.343	11.176

As a consequence of the values in Table 1 and Table 2 according to the data set; It was concluded that orange crabs (respectively: 17.11; 13.549; 34.153; 38.112; 15.478) had larger averages (respectively: 14.056; 11.928; 30.058; 34.717; 12.583) than blue when the basic statistical values of the maximum width of the shell, the midline length of the shell, the posterior region of the shell, the anterior width of the shell, the maximum width of the shell and the body depth are examined. Moreover, it is seen that females have larger back width (13.487–11.99), while males have larger averages in other variables when males and females are compared.

Table 3

Essential Statistics of Variables
	Min	Max	Average	Std. Deviation
Frontial lobe	7,20	23,10	15,583	3,495
Back Width	6,50	20,20	12,738	2,573
Shell Lenght	14,70	47,60	32,105	7,119
Shell Width	17,10	54,60	36,414	7,872
Body Depth	6,10	21,60	14,030	3,425

According to evaluations of Table 3, it is noticed that the lengths of the frontal lobes vary between 7.20 and 23.10, and the mean is 15.583 ± 3.495. It is seen that the back widths vary between 6.50 and 20.20, with the average being 12,738 ± 2,573.

Table 4

Essential Statistics of Proportional Data
	Min	Max	Average	Std. Deviation
Midline Lenght / Max. Width	,83	,93	,8808	,01994
Back Zone Width / Anterior Zone Width	,68	,98	,8251	,07464

When the shell and body dimensions calculated in Table 4 are concerned, it is comprehended that the values approach 1, which overlaps with the period when it is the most full in terms of meat. It is seen that the ratio of the body criteria was estimated as 0.8808, and the ratio of the shell criteria was calculated as 0.8251.

Table 5

Comparison of Proportional Statistics by Gender
	Gender	Average	Std. Deviation
Midline Lenght / max.Width	Male	,8876	,02060	p value: 0,000
Midline Lenght / max.Width	Female	,8740	,01676	t statistic: 5,122
Back zone width/ anterior zone width	Male	,7700	,05061	p value: 0,000
Back zone width/ anterior zone width	Female	,8802	,05005	t statistic: -15,482

The study shows it concluded that there was a statistical difference between the groups (p values < 0.05) when the averages of the sexes and crabs in Table 5 were compared. Besides, when males and females are compared, it is seen that the ratio of midline length to the maximum width of males is higher. At the same time, it is seen that the ratio of the width of the posterior region to the width of the anterior region is higher for females.

Table 6

Comparison of Proportional Statistics by Color
	Color	Average	Std. Deviation
Midline length / maximum width	Blue	,8652	,01086	p value: 0,000
Midline length / maximum width	Orange	,8963	,01386	t statistic: -17,669
Back zone width / anterior zone width	Blue	,8558	,07248	p value: 0,000
Back zone width / anterior zone width	Orange	,7944	,06361	t statistic: 6,360

According to the mean of the crabs and the color in Table 6 were compared, it was concluded that there was a statistical difference between the groups (p values < 0.05). It is seen that the ratio of midline length to the maximum width of orange crabs is higher when comparing orange and blue crabs. Therewithal, it is seen that the ratio of posterior region width to anterior region width of blue crabs is higher than that of orange crabs.

In the study completed on 200 Leptograpsus L. variegatus crabs, there were 50 blue females, 50 blue males, 50 orange females, and 50 orange male crabs.

In the Campbell and Mahon study, canonical analyzes were used on the data set. According to the results of the analysis, it was concluded that there was no dissimilarity in the dimensions in terms of colors.

This study concluded that there is statistical significance between the groups according to values in terms of the colors. When analyzed by gender, results similar to Campbell and Mahon's study were obtained. Additionally, different results were obtained in the analyzes where the shell width and front width were taken together in the same study.

Campbell ve Mahon’un çalışmasından elde edilen sonuçlar iki farklı tür olduğunu ifade etmektedir. Bu çalışmada bu iki tür arasındaki farklar araştırılmıştır. In conclusion, the results acquired from the study of Campbell and Mahon state that there are two different types. In this study, the differences between these two species were investigated.

According to the results of the analysis, when the differences between orange and blue crabs are analyzed, it is seen that the ratio of midline length to maximum width of orange crabs is higher. At the same time, it is seen that the ratio of posterior region width to anterior region width of blue crabs is higher than that of orange crabs.

Consequently, it is understood that crab meat is quality meat due to its high protein content and low-fat content. Crabs which can be counted among the high-protein food sources, come to the fore.

a. Ethics approval and consent to participate: No ethical issues related to the use of animals in the performed analyses were involved. Ethical review and approval were waived for this study, due to the crabs do not require authorization for experimental procedures.

b. Consent for publication : Not Applicable

c. Availability of data and materials : The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

d. Competing interests : We declare that we have no conflict of interest.

e. Funding : Not Applicable

f. Author Contributions: Methodology, Ö.G.; software, Ö.G.; formal analysis, Ö.G.; writing—original draft preparation, Ö.G.; writing—review and editing Ö.G; funding acquisition Ö.G. All authors have read and agreed to the published version of the manuscript.

g. Acknowledgements : The authors gratefully acknowledge the entire staff of the Aquaculture Research Center-ARC, located in the Institute of Marine and Environmental Technology-IMET, Baltimore, MD, USA, for the help with the tank system. In addition, the authors thank J. Sook Chung for the laboratory and technical support.

h. Author Information : Ege University Faculty of Fisheries, Aquaculture Department, [email protected]

Campbell N.A. and Mahon R.J. (1974). "A multivariate study of variation in two species of rock crab of the genus Leptograpsus." Australian Journal of Zoology 22, 417-425.
Balss, H. (1935). Brachyura of the Hamburg Museum expedition to south-western Australia, 1905. J. Proc. R. Soc. West. Aust. 21, 113-51.
Fabricius J.C. 1793. Entomologia systematica emendate et aucta, secundum classes, ordines, genera, species ajectis synonymis, locis, observationibus, descrptionibus
Griffin, D. J. G. (1973). A revision of the two southern temperate shore crabs Leptograpsus variegatus (Fabricius) and Plagusia chabrus (Linnaeus) (Crustacea, Decapoda, Grapsidae). J. R. Soc. N.Z. 3, 415-40.
Mahon, R. J. (1974). A study of rock crabs of the genus Leptograpsus. Ph.D. Thesis, University of Western Australia.
Milne Edwards H. 1853. Mémoire sur la famille des Ocypodiens. Annales du Science Naturelles, Zoologie, 3(20): 163–226
Paul, A. ve Haefner, JR. (1985). Biology and Exploitation of Crabs the Biology of Crustacea. Vol.10, 111-163.

No competing interests reported.

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The Research About Morphometric Characteristics on Leptograpsus Crabs

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1. Introduction

2. Materials and Methods

3. Results

4. Discussion

5. Conclusion

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