Biofluorescence, the ability to exploit light with short wavelengths, such as ultraviolet (UV) and blue, and re-emit it with lower energy and longer wavelengths, is considered a widespread phenomenon among marine animals and has many ecological roles in intra- and interspecific communication. Heterobranch sea slugs are believed to rely almost exclusively on their colour patterns for survival, with coloration serving as camouflage or as a warning to predators of heterobranch toxicity (aposematic coloration). Since solar light is progressively absorbed by seawater with a constant loss of longer wavelengths, it is unclear how heterobranch coloration can maintain its ecological role below the water surface. The present study investigates, for the first time, in situ biofluorescence in 53 species of Mediterranean Heterobranchia to determine whether these animals rely on light emission to enhance the visibility of their colour patterns. The ability to fluoresce when illuminated by UV and blue light (wavelengths <470 nm) appeared to be quite widespread among nudibranchs (i.e. found in c. one-third of the encountered species), while no evidence of light emission was found in non-nudibranch heterobranchs. The majority of fluorescent species were Cladobranchia belonging to the superfamilies Fionoidea and Aeolidioidea. Nudibranchs fluoresced in four different colours, with green being the most common. Light emission was often restricted to particular body regions, such as the cerata of Cladobranchia. These preliminary data might indicate that fluorescence plays an essential role in the enhancement of nudibranch aposematic coloration.

中文翻译：

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地中海异枝中荧光的初步证据

生物荧光是一种能够利用短波长的光（例如紫外线（UV）和蓝光，然后以较低的能量和更长的波长重新发射）的能力，被认为是海洋动物中的普遍现象，并且在种内和种间具有许多生态作用沟通。据信，杂支海几乎完全依靠它们的颜色模式来生存，其颜色可作为伪装或作为对异性分支毒性掠食性动物的警告（异位着色）。由于太阳光逐渐被海水吸收，并不断损失更长的波长，因此尚不清楚异枝色素如何在水面以下维持其生态作用。本研究首次进行了实地调查通过对53种地中海杂种支气管动物进行生物荧光检测，确定这些动物是否依靠发光来增强其颜色模式的可见性。当被紫外线和蓝光（波长<470 nm）照射时，发荧光的能力似乎在裸枝中非常普遍（例如，在c中发现）。所遇到的物种的三分之一），而在非裸枝杂种分支中没有发现发光的证据。大部分荧光物质是属于超科Fionoidea和Aeolidioidea的枝形分支。裸枝分支发出四种不同颜色的荧光，最常见的是绿色。发光通常限于特定的身体区域，例如枝状角膜的蜡状。这些初步数据可能表明，荧光在增强裸udi分生色的过程中起着至关重要的作用。