Porifera – Sponges
The sponges are a phylum of the animals with more than 7500 species. Porifera is Latin and consists of the words porus ‘pore’ and ferre ‘bear’, which then means about the same as pore bearer. Sponges can reach from a few millimetres to a height of more than 4m.
Porifera have no real tissue. Therefore, one can see them as a loose cell collection. Sponges neither have organs nor muscle, nerve, or sense cells.
Its skeleton consists of sclerites, which consist either of calcite, a form of lime, or silicic acid. Spongin plays an important role in the skeleton composition of Demospongiae.
Despite their simple structure, they are more complex than previously assumed. Porifera can, for example, perceive and react actively to light, mechanical stimuli, water currents and sediment deposits.
Habitat and Distribution
Sponges are found in all the oceans of our earth, as well as in rivers and lakes. They are found both in the polar regions and in tropical waters.
Mostly, Porifera sat on firm ground. When diving around the Canary Islands, we can observe them at almost every dive. They make up a large part of the colourful underwater world of the Atlantic. Apart from coastal regions Porifera also colonize the deep sea to a depth of 7000 m. Sponges are predominantly sessile animals. This means they live in one place.
The sponge Anoxycalyx joubini was discovered in the early 20th century during an Antarctic expedition by Jean-Baptiste Charcot. At the beginning of the 21st century the scientists Susanne Gatti and Thomas Brey then found out that the sponge is about 10,000 years old, which makes it the oldest living being after the Rocky Mountain Bristlecone Pine.