目魚類, ヨシキリザメPrionace glaucaとアカシュモクザメSphyrna lewiniの核型を簡易組織培養法を用いて観察し, Carcharhinus plumbeus, ドタブカC. obscurus, ガラパゴスザメC. galapagensisおよびヨシキリザメP. glaucaの核内DNA量を顕微分光濃度計を用いて測定した.ヨシキリザメの核型は染色体数2n=86, 中部・次中部着糸型染色体 (M-SM) =30, 次端部・端部着糸型染色体 (ST-A) =56, 腕数 (FN) =116であり, 核内DNA量は8.6pg/cellであった.アカシュモクザメの核型は2n=86, M-SM=20, ST-A=66, FN=106であった., ドタブカ, ガラパゴスザメの核内DNA量はそれぞれ, 6.0pg/cell, 6.0pg/cell, 8.5pg/cellであった.これらの結果を, 他の目魚類の核型および核内DNA量と比較した結果, シュモクザメ類の核型や核内DNA量の特徴は科魚類と同じであり, 他科魚類とは明確に異なった.また, 科魚類とシュモクザメ類では染色体のサイズとその範囲が比較的小さい.従って, これらの中・小型の中部・次中部着糸型および次端部着糸型染色体は, 動原体を含む逆位によって生じたと推定された.以上の類似性は, シュモクザメ類と科魚類の強い近縁性を示唆しており, シュモクザメ類を科に含める分類体系を支持している.

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A carcharhinid shark was caught in a set-net fishery off Wajima City in Ishikawa Prefecture, Japan. The individual was identified as a copper shark Carcharhinus brachyurus based on morphological characteristics and DNA barcoding using the 12S ribosomal RNA and cytochrome c oxidase subunit l gene (cox1) regions of the mitochondrial DNA. In Japan, the copper shark has been recorded from the Sea of Japan, including the coasts of Hokkaido, Niigata and Yamaguchi prefectures; and from the Pacific coast, including the Kashima-nada Sea, the east coast of the Boso Peninsula, Sagami Bay, the Ariake Sea and the south coast of Kyushu. This report represents the first reliable record of the copper shark from Ishikawa Prefecture.

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Fourteen speirnens of Carcharhinus galapagensis (Snodgrass et Heller) (Carcharhinidae, Elasmobranchii) were collected from the Ogasawara Islands, about 1, 000km south of Tokyo.In addition, ten living sharks taken there have been exhibited in the large tank at Ueno Zoo Aquarium.This species is closely allied to C.ohscurus (Leseuer) but is distinguishable from the latter by vertebral numbers.Up to now, twelve species of Carcharhinus are found to occur in Japan and its adjacent seas from the brief review of the genus in Japan, including C.alibmarginatus, C.hrachyurus, C.breripinna, C.dussumieri, C., Jalcitormis, C.galapagensis, C.linrhatus, C.longimanus, C.melanopterus, C.obscurity, C.plumbeus and C.sorrah.

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The bull shark, Carcharhinus leucas (Müller and Henle, 1839), previously reported from Japanese waters but without voucher specimens, is herein reported and its status as a Japanese species confirmed, from 33 specimens, including three from a riverine habitat, collected from Okinawa and Iriomote Islands, Okinawa Prefecture, Japan.

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Effects of the extraction conditions, the concentration methods and the kinds of shark on the physical properties of shark-skin gelatin gel: such as viscosity, melting and gelling temperatures, and gel strength, were investigated in order to determine suitable processing conditions for the gelatin. The skins of Walbeehm's sharpnose shark, white shark, ground shark, and blue shark were treated by liming for two weeks. Four kinds of limed shark-skin were separately heated in water by varying both heating temperatures (60-90°C) and heating periods (20 min-3h). The amount of extracted gelatin increased as the temperature increased and as the heating period was extended. Gelatin extract obtained at 70°C for 1.5h was divided into three portions. They were separately submitted to three different concentrating or precipitating methods; heating under reduced pressure (method A), lyophilization (method B), or precipitation with the addition of ethanol (method C). From the results of melting and gelling temperatures, and gel strength of the gelatin gels, method C was far superior to the others for obtaining gelatin from the gelatin extract. In method C, physical properties of the gel obtained by fractional precipitation with ethanol were reduced as the concentration of ethanol was increased. Based on the type of shark, the superiority of the physical properties of the gel was in the order of Walbeehm's sharpnose shark, white shark, ground shark, and blue shark. Physical properties of the gel from Walbeehm's sharpnose shark obtained by method C were far superior to those of commercially available cooking gelatin gel.

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Occurrences of tiger shark, Galeocerdo cuvier (Péron et Lesueur, 1822) (Carcharhiniformes: Carcharhinidae) in Sagami Bay are reviewed. It is clear from several records that the species occasionally enters to the bay. However, the record based on a specimen which guarantees the identification and various biological informations is known to only an example in this report. It is necessary to construct a network among citizens, fishermenʼs cooperatives, fisheries experimental stations, aquariums, museums, etc. for collecting of occurrence records of large elasmobranchs.

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Total 124 elasmobranch teeth were co-occurred with “Paleoparadoxiid Mizunami-Kamado specimen”. Ninety-seven specimens were identified with Galeocerdo aduncus, and other teeth were also identified with genera Carcharhinus and Squatina, except for one batoid tooth. Many bite marks were recognized on the left femur, middle phalanx of left hindlimb and left ¹⁴th to ¹⁵th ribs. The present paleoparadoxiid seemed to be preyed upon those sharks.

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