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The new labrid species, Cirrhilabrus isosceles, is described from six specimens, 31.0–56.7 mm SL, collected from the Ryukyu Archipelago of Japan and the northern reaches of the Philippines in the western Pacific Ocean. The holotype and a paratype were collected at 35 m depth from Funauki Bay, Iriomote-jima, Ryukyu Islands, while the four other paratypes were collected at 24–36 m from Fuga Island, Cagayan Province, northern Philippines. The new species is distinguished by features of the terminal-phase male: i.e. color pattern, a prominent long mid-dorsal-fin basal dark spot, and a broadly lanceolate caudal fin. Despite its atypical caudal-fin shape, the new species has similar color patterns to the Cirrhilabrus lunatus species complex, which differ in having a somewhat lunate caudal fin. Indeed, the mtDNA barcode COI sequences for the new species matches those of some other members of the C. lunatus complex, specifically C. cf. lunatus, C. brunneus, and C. squirei (shared mtDNA haplotypes among species has been documented in other Cirrhilabrus species complexes). Cirrhilabrus isosceles is sympatric with three other members of the C. lunatus complex, and apparently hybridizes with at least one of them. The new species is most often confused with Cirrhilabrus lanceolatus, based on the shared caudal-fin shape, however, the two species are not closely related: C. lanceolatus is in a different set of mtDNA lineages most closely related to C. jordani from Hawai’i, indicating that caudal-fin shape in this genus is not phylogenetically informative. A neighbor-joining tree and genetic distance matrix based on the COI marker is presented for a number of Cirrhilabrus species.

The gobiid fish Valenciennea yanoi n. sp. is described from two specimens collected in 13–20 m at Iriomote Island, Ryukyu Islands, Japan. Diagnostic features include the combination of a low first dorsal fin with a rounded margin, no black spot on the dorsal fin, 12 second-dorsal and anal-fin soft rays, no black spot and no yellow stripe on the snout, no black spot on the upper part of the eye, three narrow vivid sky-blue stripes on the lateral side of the head, and two broad orange and yellow stripes on the body reaching to the rear margin of the caudal fin. The new species is most similar to Valenciennea parva Hoese & Larson, 1994, but differs by lacking black spots on the snout and eye and by having broader orange and yellow stripes which reach the rear margin of the caudal fin.

The mangrove sediment was observed by a core（8 sampling points）and trench（3 sampling points）investigation at the Funaura Bay, Iriomote Island, Okinawa Prefecture. The age of a mangrove roots or shells including the core samples were measured by the ^14C method. Fine sand with abundant mangrove roots underlies the soil in the Backshore. The sediment of the mangrove swamp is mainly composed of weakly laminated mud. Tidal flat deposits consist of massive fine to medium sand. The section of the Funaura Bay is drawn based on these observations.

In a mangrove tidal flat of Iriomote Island, Okinawa, an experiment on utilization of empty gastropod shells by hermit crabs was carried out. One hundred twenty-seven gastropod shells of Terebralia palustris were left at the mangrove tidal flat in the Funaura Bay of the Iriomote Island. After 48 hours, these shells were re-collected and shell size and distance from an experimental point were measured. Thirty-five shells were utilized by hermit crabs. Sixty shells were not used and left as before. Most of the shells used by the hermit crabs were collected at the distance of less than 10m from the experimental point. The most moved shells by the hermit crab were too far distance of 120m from the experimental point. The small-sized shells used by hermit crabs were collected near the experimental point. But, the shells collected at a distant from the experimental point were only large ones. In the mangrove swamp, dead gastropod shells were used by the hermit crabs immediately after death and they moved the shells to a long distance on a short time.