Ogulin cave sponge(Eunapius subterraneus)
Ogulin cave sponge (Eunapius subterraneus) is the only known freshwater cave sponge in the world. Two subspecies have been described: Eunapius subterraneus subterraneus and Eunapius subterraneus mollisparspanis (Rudnica cave sponge). These sponges are endemic to the wider area of town Ogulin in Croatia. Like all other sponges they live a sessile life, meaning that they are attached to the cave walls or under the big stones where they live their entire life. They have develop effective system of filtrating water which they use for feeding, breathing and excretion. How does it look? You can imagine a sack full of channels with permanent water flow. Water is sucked through numerous tiny pores on the surface of the animal, and on its way through channels food and oxygen are absorbed while excrements are released in the outgoing water.
Both subspecies are listed in Red Book of Croatian Cave Fauna. Eunapius subterraneus subterraneus is listed in category EN (Endangered) with great risk of extinction, while Eunapius subterraneus mollisparspanis is placed in category VU (Vulnerable) according to the IUCN criterion.
Helena Bilandžija -