Bigfin reef squid

Sepioteuthis lessoniana, commonly known as the bigfin reef squid or oval squid, is a commercially important species of loliginid squid. It is one of the three currently recognized species belonging to the genus Sepioteuthis. Studies in 1993, however, have indicated that bigfin reef squids may comprise a cryptic species complex. The species is likely to include several very similar and closely related species. Bigfin reef squids are characterised by a large oval fin that extends throughout the margins of its mantle, giving them a superficial similarity to cuttlefish. They are small to medium-sized squids, averaging 3.8 to 33 centimetres (1.5 to 13.0 in) in length. They exhibit elaborate mating displays and usually spawn in May, but it can vary by location. The paralarvae resemble miniature adults and are remarkable for already having the capability to change body colouration upon hatching. Bigfin reef squids have the fastest recorded growth rates of any large marine invertebrate, reaching 600 g (1.3 lb) in only four months. They are a short-lived species, with a maximum recorded lifespan of 315 days. The diet of bigfin reef squids comprises mainly crustaceans and small fish. They are found in the temperate and tropical waters of the Pacific and Indian Oceans, and have recently been introduced into the Mediterranean as a Lessepsian migrant. They are commonly found near the shoreline, near rocks, and coral reefs. They are fished in vast quantities for human food in Asia. Because of their rapid growth rate, short life span, and tolerance to handling and captivity, bigfin reef squids are regarded as one of the most promising species for mariculture. They are also a valuable source of giant axons for medical research. Bigfin reef squids are also known as northern calamary in Australia and New Zealand, to distinguish them from the southern reef squid (or southern calamary), Sepioteuthis australis. Other common names include green-eyed squid in English; koonthal in Malayalam; oosi kanava in Tamil; calmar tonnelet in French; calamar manopla in Spanish; Großflossen-Riffkalmar in German; mu he`e in Hawaiian; 莱氏拟乌贼 in Chinese; torak in Malaysian; アオリイカ (aori-ika) in Japanese; kinn mon in Burmese; and 무늬오징어 (munuiojing-eo), 흰꼴뚜기 (huinkkolttugi), or 미즈이카 (mizuika) in Korean. Sepioteuthis lessoniana is one of the three currently recognised species classified under the genus Sepioteuthis of the pencil squid family, Loliginidae. It belongs to the suborder Myopsina of the squid order Teuthida. Sepioteuthis literally means 'cuttlefish squid', from Greek: σηπία (sēpía, 'cuttlefish') and τευθίς (teuthis, 'squid'). It was first described by the French naturalist André Étienne d'Audebert de Férussac and named after René Primevère Lesson. The type specimen was collected by Lesson off the coast of New Guinea during the circumnavigational voyage of the French corvette La Coquille (1822–1825) under the command of Louis Isidore Duperrey. Numerous other species of Sepioteuthis were described from the Pacific and Indian Oceans in the late 19th century and in the early 20th century. In 1939 the Belgian malacologist William Adam examined the specimens of Sepioteuthis recovered from the tropical western Pacific. He synonymised the twelve species then considered valid under Sepioteuthis lessoniana. A study in 1993 by Segawa et al. revealed that the population of S. lessoniana in Okinawa may actually be composed of three distinct species. This was confirmed in genetic studies by Izuka et al. in 1994. Triantafillos and Adams in 2005 also showed that S. lessoniana in Shark Bay, Australia is composed of two species. These findings indicate that S. lessoniana may actually comprise several very similar and closely related species. It is now believed that S. lessoniana is a cryptic species complex. Like other members of the genus Sepioteuthis, bigfin reef squids are easy to distinguish from other squids in that they possess thick and muscular oval fins that extend around almost the entire mantle. The fins extend about 83 to 97% of the mantle length and are 67 to 70% of the mantle length in width. Because of these fins, bigfin reef squids are sometimes mistaken for cuttlefish, a fact reflected by their scientific names. A narrow blue or white line is visible at the point of attachment of the fins to the mantle. A fleshy ridge is also present where the fins meet at the back of the squid.