Disorder of symmetry in the marine starfishes of the Amursky Bay of Japan Sea

Abstract

The marine starfishes have usually radial five-armed symmetry. But some diversions were described. So, occurrence of specimens with 4-7 arms is described in big Indian star Oreaster reticulates that normally have 5 arms. We explored frequency of disorder in five-armed symmetry of starfishes Asterias amurensis and Patiria pectinifera from Amursky Bay of Japan Sea. Samples of Asterias amurensis taken on the shallow waters stripe near Skrebtsova Island from 0.5-2.5 m depth in 1992 consited of more than 10,000 specimens and samples of Patiria pectinifera included more than 5000 specimens. Frequency of occurrence of anomalous starfishes was determined regarding number of arms. Among 11520 starfishes of normally five-armed Asterias amurensis there were found 2 specimens of 4-armed, 13 specimens of 6-armed, 5 specimens of 7-armed, 1 specimen of 3-armed ones. In case of decrease in number of arms we counted only such animals, which had no signs of secondary loss. Specifically, it was noted that deviation from five-armed specimen often was observed towards increase in number of the feature, The 4-armed specimens as it was found in Asterias amurensis were encountered seldom. High frequency of anomalous starfishes in the Amursky Bay is associated apparently with higher rate of contamination factors by heavy metals and toxicants of production that are specific for this bay.