2018Iceland’s Seabed Ecosystem III - First Day Cover block of 4

Sponges (Porifera) are multicellular organisms which differ from all other multicellular organisms both with regard to structure and physiology. The sponge depicted on the stamp lives in Icelandic waters but has not received an Icelandic name. The Latin term is Mycale lingua. Sponges take in their food in an unusual way because they do not have mouths like other multicellular organisms. They draw water through innumerable pores in which choanocytes, cells covered with cilia, feed on organic debris particles and microscopic life forms. In the course of one day sponges can draw several litres of seawater through these pores, thus receiving sustenance. Sponges are in all likelihood the oldest multicellular organisms in the story of evolution.