Supernumerary median fin-rays in teleostean fishes

Supernumerary fin-rays in the dorsal and anal fins are those that articulate directly with the head of the first proximal radial; they lie in front of the ray serially associated with the first radial. The argument presented here is that just as the number of fin-rays per dorsal and anal radial has decreased in actinopterygian history, so the number of dorsal and anal supernumeraries has decreased in teleosts. It is proposed that D > 3 and A > 3 (more than three dorsal and anal supernumeraries) is the condition primitive for teleosts, and that D2 and A3 are primitive for acanthomorphs.     

Hypoxia tolerance of two centrarchid sunfishes and an introduced cichlid from karstic Everglades wetlands of southern Florida, U.S.A.

In this study, the hypoxia tolerance of three Everglades fishes, two native centrarchids ( Lepomis gulosus and Lepomis marginatus ) and a recently introduced cichlid ( Hemichromis letourneuxi ), were documented. Aquatic surface respiration (ASR) thresholds were lowest for H. letourneuxi , followed by L. gulosus , then L. marginatus . The ASR thresholds for L. marginatus were within ranges reported for small, freshwater tropical fishes, while those for L. gulosus were similar to swamp-adapted fishes. For H. letourneuxi , ASR thresholds were some of the lowest reported. All three species showed excellent tolerance of low dissolved oxygen levels when allowed access to the surface. When denied surface access, L. marginatus lost equilibrium at a higher oxygen tension than the other species. Overall, although all species easily tolerated hypoxia, H. letourneuxi appeared to be best equipped to deal with hypoxia, followed by L. gulosus , then L. marginatus . Hemichromis letourneuxi also exhibited more aggressive behaviours than the centrarchids. These results suggest that hypoxia is not likely to prevent H. letourneuxi from exploiting the seasonally inundated wetlands of south Florida while expanding its range there.     

白鲟年龄鉴定及其生长的初步研究

以齿骨和胸鳍条为年龄鉴定材料,通过其骨磨片比较研究,结果显示用胸鳍条鉴定白鲟的年龄较为可靠。所收集的６６尾白鲟样品中,根据胸鳍条鉴定年龄,幼鲟８尾,１－３龄。成鱼５８尾中,雄鱼３３尾,最低６龄,最高１１龄,多数个体为８－９龄。雌鱼２５尾,最低７龄,最高１７龄,多数为１０－１２。白鲟生长速度快,特别在第一年其长度生长最为突出。当年１０月份的幼鱼全长达５３－６１ｃｍ,１龄鱼平均全长７５ｃｍ。推算结果表明雌雄鱼在性成熟前生长无明显差异,性成熟后,雌鱼的长度及重量均大于相同年龄雄鱼。采用ＶＢＧＦ描述白鲟全长及体重的增长。     

Effect of Active-Passive Deformation on the Thrust by the Pectoral Fins of Bionic Manta Robot

Bionic manta underwater vehicles will play an essential role in future oceans and can perform tasks,such as long-duration reconnaissance and exploration,due to their efficient propulsion.The manta wings'deformation is evident during the swim-ming process.To improve the propulsion performance of the unmanned submersible,the study of the deformation into the bionic pectoral fin is necessary.In this research,we designed and fabricated a flexible bionic pectoral fin,which is based on the Fin Ray® effect with active and passive deformation(APD)capability.The APD fin was actively controlled by two servo motors and could be passively deformed to variable degrees.The APD fin was moved at 0.5 Hz beat frequency,and the propulsive performance was experimentally verified of the bionic pectoral fins equipped with different extents of defor-mation.These results showed that the pectoral fin with active-passive deformed capabilities could achieve similar natural biological deformation in the wingspan direction.The average thrust(T)under the optimal wingspan deformation is 61.5％higher than the traditional passive deformed pectoral fins.The obtained results shed light on the design and optimization of the bionic pectoral fins to improve the propulsive performance of unmanned underwater vehicles(UUV).     

Function and structure in the paired fins of scorpaeniform fishes

Synopsis The paired fins of the basic, ancestral type of free-swimming acanthopterygian teleost serve primarily in guiding the forward course of movement and in maneuvering within the water column. In various scorpaeniform fishes the paired fins have taken on a number of other functions associated with a bottom-living mode of life. Among these are: defense against predation, probing for food items, propping the forward part of the body away from the bottom, progressing over it, digging into it, and the development of a suction disc for attachment to it. The relationship between these developments and paired-fin structure is the subject of the paper.     

Asymmetric hybridization between two species of sunfishes (Lepomis: Centrarchidae)

Many of the sunfishes (Centrarchidae) hybridize in natural systems, yet little is known about the interactions among hybridizing individuals in nature. We used allozyme electrophoresis to identify interspecific hybrids between bluegill (Lepomis macrochirus) and pumpkinseed (L. gibbosus) in Lake Opinicon, Ontario, and restriction fragment length polymorphism analysis of mitochondrial DNA (mtDNA) to identify the maternal parentage of those individuals. All 44 individuals collected and identified electrophoreti-cally as F₁ hybrids had a pumpkinseed mtDNA haplotype, indicating that hybridization between these species in Lake Opinicon is asymmetrical; F₁ hybrids result only from matings between female pumpkinseed and male bluegill.     

Fin abnormalities of pikeperch in coastal areas off the Finnish south coast

Pikeperch Stizostedion lucioperca from two different water areas off the Finnish south coast were affected by three types of fin abnormalities: fin anomalies, acute fin erosion (fin rot) and healed fin erosion. Fin erosion occurred at high prevalences at both areas, while fin anomalies occurred mainly in the area polluted by sewage.     

关于中国国家自然地图集中的中国植被区划图

 本文将中国植被区划的原则、依据、指标和标志作了明确说明和区分。将中国植被区划系统分为4级：超级单位为植被带,全国分为森林带、草原带和荒漠带。第一级单位为14个植被区域,第二级单位为植被地带,第三级单位为植被区。对这些区划单位的划分,充分吸取了以往历次中国植被区划方案的成果,并对很多区域单位的界线,依照新资料作了改动。