Hollow newt - Hollow newt (English spelling) olm

A newt of the family Sauridae in the class Amphibians. It is also called Olm. It is found in the limestone areas of the western part of the former Yugoslavia, southern Austria, and northeastern Italy, facing the Adriatic Sea. Its body is long and cylindrical, with a flattened tail. Most individuals are grayish-white, but some are reddish or yellowish. Its limbs are small, with three fingers on the front limbs and two on the back limbs. It has three pairs of pink gills at the back of its head. Its eyes are small and degenerate, and have no function. Its mouth is also small. It is 20-25 cm long, occasionally reaching 30 cm. It lives in running water and puddles in limestone caves, and is completely aquatic. It lurks in the depths, but also appears near the surface. The water temperature in its habitat is 5-10°C. It eats small crustaceans in the groundwater. If kept in a bright place, it will turn black in a few months. Fertilization occurs internally, with females laying one or two larvae that are about 10 centimeters long. In indoor water temperatures above 13°C, they lay about 50 eggs, but most of them do not develop. The eyes of the larvae are more developed than those of the adults.

[Mitsuru Kuramoto]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

両生綱有尾目ホライモリ科のイモリ。オルムともいう。アドリア海に面した旧ユーゴスラビア西部、オーストリア南部、イタリア北東部の石灰岩地帯に分布する。体は細長い円筒状で尾は扁平(へんぺい)。灰白色の個体が多いが、赤み、黄みがかったものもいる。四肢は小さく、指は前肢に3本、後肢に2本。頭の後方に3対のピンク色のえらをもつ。目は小さく退化し、機能はない。口も小さい。全長20～25センチメートルで、まれに30センチメートルに達する。鍾乳洞(しょうにゅうどう)内の流水や水たまりに生息し、完全に水中性である。深みに潜んでいるが、水面近くにも現れる。生息場所の水温は5～10℃。地下水中の小形甲殻類を食べる。明るい場所で飼育していると、数か月で黒化する。体内受精で、雌は全長約10センチメートルの1、2匹の幼生を産む。室内で13℃以上の水温では約50個の卵を産むが、ほとんど発育しない。幼生の目は成体よりも発達している。

［倉本　満］

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