Boleophthalmus pectinirostris, commonly known as the great blue spotted mudskipper and , is a species of mudskipper native to the Northwest Pacific. It can be found on the coastlines of Japan, eastern China, Sumatra, Malaysia, Taiwan and the Korean Peninsula. Description Individuals of B. pectinirostris are predominantly greenish-grey in colour, with prominent sky blue speckles across their body, including their fins and on the skin below their eyes. Taxonomy Etymology B. pectinirostris'''s generic name, Boleophthalmus, is derived from the placement of the fish's eyes, which can be raised above the level of their orbits. It is taken from the Greek bole ('ejected') and ophthalmon ('eye'). The specific epithet is a compound Latin form, taken from pecten ('comb, rake') and rostrum ('beak'), and likely refers to the incised teeth of the fish's mandible, which it uses to scrape its food off the surface of the ground when on land. Phylogeny Phylogenetic analysis of B. pectinirostris conducted in 2014 found that the species may in fact include at least two cryptic species as part of a species complex; one being native to the South and East China Sea, and another being found in the Strait of Malacca northward towards Taiwan. Habitat and distributionBoleophthalmus pectinirostris can be found in Peninsular and eastern Malaysia, Sumatra (Indonesia), China, Taiwan, Korea, and Japan, living in warm tropical and sub-tropical estuaries. As a euryhaline species, it can also survive in a wide range of salinities. It prefers muddy areas near river mouths and mangroves, where it is easier to burrow in. Its presence in Malaysia and Sumatra was confirmed in 2009, where it is sympatric with Boleophthalmus boddarti. Prior to 2009, the populations in this region were misidentified as the species Boleophthalmus dussumieri, another species in the same genus which is related to both B. boddarti and B. pectiniriostris. Behaviour Burrowing Like other mudskippers, B. pectinirostris is able to move on land, using its pectoral and pelvic fins to clamber over the surface of tidal flats in its habitat at low tide. Using its tail, it can also hop across the ground to move faster. During high tide, the night, or when its predators are present, the fish retreats into a burrow, dug to a depth of approximately below the surface, becoming active again during the day or when the threat has passed.Boleophthalmus pectinirostris use their mouths to move soil and maintain their burrows, in the process