Peculiar Star Fish Protoreaster linckii (Echinodermata: Astroidea) from Tuticorin Coastal Water, Gulf of Mannar
G Chelladurai1* and A Doss2
1Department of Zoology, Kamaraj College, India
2Department of Microbiology, Kamaraj College, India
Submission: October 01, 2016; Published: December 02, 2016
*Corresponding author: G Chelladurai, Department of Zoology, Kamaraj College, Tuticorin, Tamil Nadu, India, Email:firstname.lastname@example.org
How to cite this article: G Chelladurai, A Doss. Peculiar Star Fish Protoreaster linckii (Echinodermata: Astroidea) from Tuticorin Coastal Water, Gulf of Mannar. Ocean & fish Open Access J. 2016; 1(2): 555559. DOI: 10.19080/OFOAJ.2016.01.555559
Starfish (Protoreaster linckii) was collected from Tuticorin coast. The species generally have 5 arms, but an unusual abnormal sea star, Protoreaster linckii was found with 6 arms. Furthermore, its length, weight, and arm’s length were also measured and tabulated.
Keywords: Gulf of Manner; Sea star; Dorsal view; Irregular shape and arms; Protoreaster linckii
Starfish are a group of marine invertebrates that exist in ecosystems with sea grass, coral, rocky substratum, etc., from shallow areas to the deepest regions in the ocean. They typically have a central disc and five arms, though some species have a larger number of arms. The aboral or upper surface may be smooth, granular or spiny, and is covered with overlapping plates. Starfish have tube feet operated by hydraulic system and a mouth at the center of the oral or lower surface. The class Asteroidea is one among the various groups within the phylum Echinodermata, including nearly 1900 extant species grouped into 36 families, and approximately 370 extant genera. Asteroids occur at all depths from the intertidal to the abyssal and are present throughout all over the world’s oceans, but are most diverse in the tropical Atlantic and Indo-Pacific regions [1-3].
Starfish are an essential part of marine food chains, eaten as larvae, and becoming voracious predators upon reaching adulthood, with their prey including mollusks and other marine organisms. Echinoderms are the notable sources of bioactive compounds from marine kingdom. They are subdivided in five classes, including crinoids (sea lilies and feather stars), asteroids (starfishes), ophiuroids (brittle stars), echinoids (sea urchins and sand dollars) and holothuroideas (sea cucumbers). For example, steroidal glycosides are the principal compound present in starfish and are responsible for its general toxicity. Over 500 polyhydroxylated steroid compounds were designated from different starfish species . These glycosides have many bioactivities like cytotoxic, haemolytic, antimicrobial, expectorant, antitussive, antiasthmatic, analgesic and other activities .
The sea star Protoreaster lincki has a gorgeous appearance is relatively larger in size and can grow up to 30 cm in total length, with five short triangular arms that have bright red or orange reticulate patterns on their dorsal sides. Starfish have an evolutionary history that spans five hundred million years, beginning in the Cambrain period, wherein the dominate species have always exhibited pentamersal symmetry. Starfish with five arms may evolve to have other number of arms. Above or below the normal arm count is considered as an abnormality. The present study concerns the occurrence of abnormality in P. linckii from the catch of Tharuvaikulam, Tuticorin coastal region, Gulf of Mannar, India.
Starfishes were collected from trawl by catch landing at Tharuvaikualm fishing harbour (Latitude 8o89′N Longitude78o16′E), Gulf of Mannar, in December 2015 (Figure 1). Among the 85 specimens of Protoreaster linckii (Figure 2) collected, 84 specimens were found to be normal and only one was abnormal.
Specimens were collected from Tuticorin landing center
by standard method. Collected specimens were brought to the
laboratory where they were washed under running tap water
to remove the adhered mud and other particles. After remove
all the unusual particles, it was measured, weighted and the
reading were noted. Then the specimens were preserved in 10
% formalin for further work.
Specimens (Protoreaster linckii) were collected from Bay of
Bengal, Tuticorin coastal region, Tamil Nadu, South India (Figure
1). Among the various specimens collected, one had the abnormal
arm numbers (6 arms) (Figure 2). The collected abnormal
specimens (starfish) were measured and values were tabulated.
The abnormal starfish was very different in length and size.
Lengths of the arm R (from the mouth center to the tip of arm in
mm), r (from mouth center to the end of inter radius) and arm
breadth b (at the base of arm) of the sea stars were measured
using calipers and weight of the specimen was measured by
electronic machine (Tables 1 & 2). Echinoderms are efficient
scavengers within their respective marine ecosystems and it
plays an important role in maintaining the marine ecological
functions in the sea.
The control of ray number is very precise in five-rayed
species. Four or three arms formed during the metamorphosis
is the result of teratological incomplete development, which
is generally consistent with the observations on Echinaster
spinulosus [6,7]. The present evidence points that ray number
abnormalities in asteroids can be caused by high salinity during
early development. The six and four armed starfish A. indicus, P.mamailatus and L. Multifora were observed from Gulf of Mannar
region . Hence, further studies are needed to understand
the reasons for causing abnormality and genetic diversity
between normal and abnormal sea star. Similar to these cases
is the occurrence of abnormal four-armed red-knobbed starfish
Protoreaster linckii (Echinodermata: Astroidea), Tuticorin coast,
south-east coast of India .
It has been previously reported about the occurrence of
abnormal starfish Astropecten indicus (Echinodermata: Astroidea)
along Southeast coast of India . Recent observations of the
abnormal development of some star fish from Gulf of Mannar
suggest that deviations from pentamerism are not a heritable
character but are a consequence of environmental perturbations
on the metamorphosis of larvae and/or abnormal regeneration
of arms . The possibility of the over exploitation of this
species, along with its habitat destruction by coral mining,
warrants the initiation of conservation and also the necessity to
study its impacts on the ecosystem. The present report describes
abnormality in this species that was observed for the first time
on the Indian coast.
The first Author is thankful to INCOIS- OSF Project (Grant
No: F&A:OSF/A2:XII:014.Dt06/06/2014), Ministry of Earth
Sciences (MoES) (Government of India), for providing financial
support, and Kamaraj College, Manonmaniam Sundaranar
University, Tuticorin for providing facilities and encouragement.