海蛍 Umi Hotaru: The Ninja’s Nighttime Guide

海蛍（Umi Hotaru）：忍者的暗夜向导

在潜行与谋略的世界里，忍者曾巧妙利用「海蛍」（Umi Hotaru，学名：Vargula hilgendorfii）这一神奇的自然现象作为夜间行动的向导。本文将深入解析他们如何匠心独运地运用这些生物发光生物执行暗夜任务。

一、黑暗中的光明之术

忍者会寻觅海底为沙质的清澈海域 —— 这是海蛍的理想栖息地。他们用诱饵精准吸引并收集这些发光生物，甚至能将其养活至需要之时，展现出对自然的深刻理解与资源利用智慧。

这些生物成为隐秘的光源，使忍者能在不被敌人察觉的情况下阅读地图、向盟友发送信号。这种方法不仅体现了他们的生存技能，更彰显了其解决问题的创新思维。

利用海蛍的实践，揭示了忍者智慧的深度 —— 他们能与自然世界融合，将简单的生物转化为间谍活动与通讯的工具。

二、《秘蔵の伝書》（Hizō no Densho）选段译解

以下是来自矢寿駄流（Yasuda-ryū）的《秘蔵の伝書》片段翻译：

关于海蛍（Umi Hotaru）

• 采集时机与环境：最佳时机是没有月光的漆黑夜晚。海蛍仅栖息于海底为沙质的洁净海域，水深约 3 至 5 尋（注：非标准单位，或指绳索牵引 3-5 次的长度）。若有突出的码头或类似结构，环境则更为理想。

• 诱捕方法：将鲣鱼、黄尾鱼或鲭鱼的头部切成两半，穿在绳上投入海中。默数 500 下后将其提起，在海水桶中冲洗，每次约收集 20 只海蛍。

• 存活保存技巧：若需将海蛍养活至次日清晨，需使用透水性能良好但缝隙不超过 1 分（3.03 毫米）的木箱 —— 以防它们逃入沙中。切记此点！

• 干燥处理步骤：清晨用筛子将海蛍与鱼肉分离（若夜间采集时即分离并放入另一木箱则更佳），置于细网中在晨光下晾晒。约 15 至 30 分钟后，其外壳会变得透明；若仍呈不透明白色，则无法发光，视为次品。

• 应用场景与注意事项：

• 可用于驱赶老鼠、大型鸟类及昆虫（此点记载存疑，为口头传承）。雨天需注意，海蛍可能被冲走损坏。
• 若无水，可用尿液暂存。
• 需与盟友约定固定的附着方法。

夜间路径的海蛍应用

• 位置选择：

• 涂抹于树根基部：即使下雨，沿树干流下的水也不易将其冲掉，但暴雨时树根基部仍不适宜。
• 暴雨时：折断树枝并朝路径方向固定，在海蛍附着处上方绑扎树枝，任务返回时移除，效果甚佳。

• 高度与时长：

• 海蛍加水后，每英寸可发光约 1.5 分钟。春、秋、冬季效果最佳，夏季可持续约 15 分钟。
• 高处（攀爬固定耗时）与低处（易被发现）均非理想，矢寿駄流认为离地 1 英尺处为最佳高度。

• 通讯密码体系：用站立 1/2/3、水平 1/2/3、L 形 1/2/3、圆圈（粗画）1/2/3、“目” 形 1/2/3 等组合传递信息。有风时使用 “风车” 装置 —— 旋转的火光（高处使用）效果极佳，需根据风力决定绳索长度，且装置背面不附着海蛍。

• 战术伪装：将海蛍固定在树枝上，借风力使其旋转，仅单面涂有海蛍，形成忽明忽暗的效果，且不可置于伸手可及之处，可用于迷惑敌人或向盟友示警。

三、文化与科学的交织

• 词源与象征

  ：“海蛍”（Umi-hotaru）中，“海”（Umi）点明栖息地，“蛍”（Hotaru）呼应其发光特性，体现忍者文化对自然现象的诗意命名。

• 生态智慧

  ：忍者对海蛍栖息地（沙质海底）、发光时长（受季节影响）的精确掌握，暗合现代生物学对发光生物（如荧光素酶反应）的认知。

• 战术哲学

  ：利用生物发光进行非语言通讯，展现了 “以自然制自然” 的忍者思维 —— 正如《孙子兵法》“因粮于敌” 的智慧，他们将海洋生物转化为 “活体信号灯”，在黑暗中构建隐秘的信息网络。

结语：自然与谋略的共生

对忍者使用海蛍的探索，揭示了自然、战略与生存的奇妙交汇。在没有现代光学设备的时代，他们以对生物习性的洞察打破黑暗的桎梏，将海洋中的微光转化为战术优势 —— 这种 “与自然协作” 的智慧，恰是忍者文化中最令人称奇的生存哲学。

（注：本文翻译参考服部正树《忍法大全》收录的矢寿駄流古传文献，部分术语因流派特殊性保留日文原词以确保准确。）

英文原文：

海蛍 Umi Hotaru: The Ninja’s Nighttime Guide

In the realm of stealth and strategy the Ninja once harnessed 海蛍 Umi Hotaru, sea-fireflies (Vargula hilgendorfii) a remarkable natural phenomenon as a nighttime guide. This essay delves into their ingenious use of these bioluminescent creatures for night operations.

The Art of Light in Darkness

The Ninja sought clear seas with sandy bottoms, ideal habitats for sea-fireflies. Using bait, they attracted and collected these luminous beings with precision. Ninjas kept them alive until needed, showcasing an exceptional understanding of nature and resourcefulness.

These creatures served as a subtle light source. They enabled ninjas to read maps and signal allies undetected by enemies. The method not only reflects their survival skills but also their innovative approach to problem-solving.

The practice of using sea-fireflies illuminates the depth of ninja ingenuity. It exemplifies their ability to blend with the natural world, turning simple organisms into tools of espionage and communication.

Below is a small segment from the Hizō no Densho from the Yasuda-ryū translated.

Regarding 海蛍 Umi Hotaru

Dark, moonless nights are best. Sea fireflies are found only in beautiful seas with sandy bottoms, up to three to five Hiro (a unit of measurement) deep. If there’s a protruding dock or similar structure, it’s especially good. Cut the heads of bonito, yellowtail, or mackerel in half, thread them, and throw them into the sea. Lift them after counting to 500 to wash off in a bucket of seawater. Put about twenty in seawater, lift and collect them one after another.

To keep them alive until the next morning, use a box that allows seawater to flow through well but doesn’t have gaps larger than 一分 one Bu (3.03 mm); otherwise, they might escape into the sand. Don’t forget this.

In the morning, separate them from fish flesh using a sieve (if separated when collected at night and placed in another box, it’s even better), lay them on a fine net, and dry them in the morning sunlight. They dry in about a quarter or half an hour; the shell becomes transparent, and only the white, opaque ones won’t glow. Bad.

– Good for use against rats, large birds, and insects (this is unclear). Oral tradition. Be careful when it rains; they can wash away and be ruined.

– If there’s no water, urine is also fine.

– Discuss the method of attachment with allies.

– To inform those coming later.

– For use on the way back. In places invisible to the enemy but visible to the infiltrator, bad places, good places (when facing the enemy outward), west, near the entrance of lavatories, from that place visible, rarely visited by people but clearly visible, inside a pond (moats are bad because they’re too wide), under eaves, under the floor, at the folding point of a ladder ascending from below, at a stone dropping point.

About 海蛍 Umi Hotaru on night paths.

– Apply at the base of trees. Even if it rains, the water sliding down the tree won’t wash it away. Heavy rainfall is bad for the base of the tree.

– If it’s raining heavily, break a branch and attach it in the direction of the path. Tie the branch above where the firefly is attached. When returning from a ninja mission, remove it. Fireflies are good.

– When water is added, they can glow for about one and a half minutes per inch and minute. Good in spring, autumn, and winter; in summer, they last for about a quarter of an hour. Good.

– High places (climbing up to attach takes time), low places are easily discovered. However, since Yasuda-ryū’s fireflies are used at night, one foot above the ground is best.

– To inform and communicate with those coming later. Use standing 1, 2, 3, horizontal 1, 2, 3, L-shaped 1, 2, 3, circle (draw thickly) 1, 2, 3, “me” 1, 2, 3, all types of combinations. Windmills are good in windy conditions – spinning fire (used in high places) is very good.

– Decide the length of the string based on the wind’s strength. No fireflies on the back.

– Attach to a tree branch. With the wind, it spins, having fireflies painted on one side only, so it appears and disappears. Do not attach within reach.

– To distract the enemy or as a sign for allies. Decide the length of the string based on the wind’s strength.

– For transport, just roll it up.

– Dark nights are preferable, but if there’s a moon, the lower, darker spots are best.

– High trees within a forest are very good. However, decide by throwing a string over them. But it should be visible from below.

This translation was done by ChatGPT and may not be 100% accurate. I suggest you go to Sean Askew’s web site and find a better translation. The whole 秘蔵の伝書 Hizō no Densho from 矢寿駄流 Yasuda-ryū is published in the end of Masaaki Hatsumi’s book 忍法大全 Ninpō Taizen.

Footnotes:

海蛍 (Umi-hotaru): Sea-firefly. “海” (umi) means sea, reflecting their habitat. “蛍” (hotaru) means firefly, indicating their bioluminescent nature.

奇麗 (Kirei): Beautiful. “奇” signifies strangeness, “麗” beauty, together highlighting the aesthetic appreciation in the ninja culture.

暗夜 (An’ya): Moonless night. “暗” means dark, “夜” night, emphasizing their preference for operations under cover of darkness.

砂地 (Sajichi): Sandy bottom. “砂” refers to sand, “地” to earth or ground, indicating the sea-firefly’s preferred habitat.

尋 (Hiro) or 広 (Hiro): It is not a standard measuring unit, it probably means pull this rope three to five times.

矢寿駄流 (Yasuda-ryū): This old Ninjutsu school did not survive to modern times, but their Densho is still held by a few researchers such as Hatsumi Sōke.

This exploration into the ninja’s use of sea-fireflies reveals a fascinating intersection of nature, strategy, and survival.