Studies on the identification, properties and function of chitin in sponges (Porifera), which are recognized as the first multicellular organisms on Earth, continue to be of fundamental scientific interest. The occurrence of chitin has so far been reported in 21 marine sponge species and only in two inhabiting fresh water. In this study, we present the discovery of α-chitin in the endemic demosponge Ochridaspongia rotunda, found in Lake Ohrid, which dates from the Tertiary. The presence of chitin in this species was confirmed using special staining, a chitinase test, FTIR, Raman and NEXAFS spectroscopy, and electrospray ionization mass spectrometry (ESI-MS). In contrast to the case of marine sponges, chitin in O. rotunda has been found only within its holdfast, suggesting a role of chitin in the attachment of the sponge to the hard substratum. Isolated fibrous matter strongly resemble the shape and size of the sponge holdfast with membrane-like structure.

海绵（Porifera）中几丁质的鉴定，性质和功能的研究一直被认为是基础科学兴趣，海绵是公认的地球上最早的多细胞生物。迄今为止，已经报道了21种海洋海绵物种中仅有几丁质的甲壳素的存在，只有两种居住在淡水中。在这项研究中，我们介绍了在奥赫里德湖（Ohrid Lake）发现的第三种地方性圆形海绵体Ochridaspongia rotunda中发现的α-甲壳质。使用特殊染色，几丁质酶测试，FTIR，拉曼光谱和NEXAFS光谱以及电喷雾电离质谱（ESI-MS）证实了该物种中几丁质的存在。与海洋海绵的情况相反，圆形大厅中的几丁质仅在其坚牢度内发现了甲壳素，表明几丁质在海绵与硬质基质的附着中起作用。分离的纤维物质非常类似于具有膜状结构的海绵固定物的形状和大小。