Random Article Summary #131

The sharptail mola (Masturus lanceolatus) is a type of mola found around the world in both tropical and temperate waters. It looks similar to the ocean sunfish, but it can be identified by a projection on its clavus, which acts like a pseudo-tail. It is also known by names such as sharpfin sunfish, point-tailed sunfish, and trunkfish. Because it is rarely seen, scientists know very little about its biology or how it lives through its life cycle. Recently, it has become important to commercial fisheries off eastern Taiwan. The sharptail mola is the only species in its genus. The sharptail mola lives worldwide in tropical and temperate oceans. It mostly stays in the upper ocean during the day at depths around 5 m, typically in water warmer than 20 °C, though it makes repeated deeper dives into cooler water. At night it stays deeper, usually between 100 and 250 m, and it has been recorded as deep as 670 m (possibly deeper than 1,000 m); a tagged fish in the Gulf of Mexico traveled about 10 km per day on average. The sharptail mola is one of the largest bony fishes, reaching about 3.4 m in length and up to 2,000 kg. It has an oval body, forward-placed eyes, beak-like fused teeth, and dorsal and anal fins that join into a clavus instead of a separate tail fin. Its silvery coloring with darker upper sides and gray fins helps it stand out, and it differs from a similar species by features like its chin and the different lengths of its dorsal and anal fin bases. Early studies suggested sharptail molas might be unusual sunfishes keeping larval traits, but it is now understood that their tail-like projection develops after the main tail is lost. They swim using long dorsal and anal fins, with the anal fin doing most of the work, and feed differently as they grow: juveniles eat bottom-dwelling worms and sponges, while adults likely eat jellyfish and related animals, plus some fish and small invertebrates. Sharptail molas are very productive egg-layers; juveniles pass through a spiny “Molacanthus” stage before the spines fade, and the species may live about 85 years (males) and 105 years (females). A festival in Hualien County, Taiwan, increased demand for sunfish meat, shifting sales from only intestines and reproductive organs to the whole fish. As a result, sunfish catches off eastern Taiwan have risen sharply, with sharptail mola making up about 90% of the catch. In 2005, 208 tonnes were landed, but researchers are now investigating how this higher fishing pressure may be affecting sunfish stocks.