Gecko Catshark

Attaining 40 cm (16 in), possibly 50 cm (20 in) in length, the gecko catshark has a slim, firm body and a fairly short head that comprises less than one-fifth of the total length. The snout is flattened with a blunt tip. The nostrils are large and divided by triangular flaps of skin on their anterior rims. The eyes are large and horizontally oval, with rudimentary nictitating membranes (protective third eyelids) and indistinct ridges underneath. The mouth is sizable and forms a long arch; there are well-developed furrows around the corners. The teeth are small and number around 47 rows in the upper jaw and 50 rows in the lower jaw; each has a narrow central cusp and typically two pairs of smaller cusplets on the sides. The five pairs of gill slits are short, with the fourth pair about level with the pectoral fin origins. The first dorsal fin has a blunt apex and is positioned over the latter half of the pelvic fin bases. The second dorsal fin resembles the first but is slightly smaller, and is positioned over the latter third of the anal fin base. The pectoral fins are rather large and broad, with rounded corners. The pelvic fins are small with angular margins; the claspers of adult males are short and do not reach the anal fin. …

The range of the gecko catshark extends from southern Japan, where it occurs off the Shizuoka and Mie Prefectures of Honshu and the main islands of Shikoku and Kyushu, to the East China Sea including Taiwan. It is extremely abundant in Japanese waters. Further records from off Vietnam may be erroneous. This species is found in water 100–900 m (330–2,950 ft) deep, on or close to the sea floor. It seems to exhibit strong spatial segregation by sex.

Schooling in nature, the gecko catshark feeds opportunistically on a wide variety of bony fishes (including lanternfish), cephalopods (including sepiolid and enoploteuthid squid), and crustaceans (including isopods, amphipods, krill, and decapods). The relative importance of the three prey categories varies between geographical areas and seasons, likely reflecting what is most available in the environment. This species is oviparous; adult females have a single functional ovary, on the right, and two functional oviducts. A single egg matures within each oviduct at a time. Mature eggs are contained within smooth, translucent yellow, vase-shaped capsules measuring roughly 6 cm (2.4 in) long and 1.6 cm (0.63 in) across, with the top squared off and the bottom converging on a short projection. One study in Suruga Bay recorded females with large yolked ova inside the ovary year-round, but females in the western part of the bay were only found to carry egg cases from October to January, suggesting that the interval between egg depositions is shorter at that time. Males and females attain sexual maturity at approximately 31–32 cm (12–13 in) and 36–37 cm (14–15 in) long respectively. However, there is a Taiwanese record of an immature male 38 cm (15 in) long.

Although the honor for this Catshark is not named, it is possibly in honor of fish paleontologist Charles Rochester Eastman (1868-1918).