The Spirastrella sponge

Ever since I was studying Biology at the University of Barcelona, I have been particularly interested in marine sponges. I photographed this red sponge, Spirastrella cunctatrix), in the Mediterranean sea (Costa Brava). For the publication in 1986 of the massive opus, Història Natural dels Països Catalans,  (15 volumes), I contributed a large number of photographs with comments, and among them, needless to say, there were many sponges.

They reside in the dark rocky depths close to the shore, but when they are exposed to artificial light they show off their marvellous colours. But there is nothing ostentatious about their display. At first sight they seem immobile, but in their interior they possess tiny cells with a flagellum, known as choanocytes, which stir up the water and thus generate a sufficient stream to enable the bacteria, unicellular algae and organic remains to circulate through their internal canals and to be held their as a food source. Some of them, like this Spirastrella have enormous conduits close to the surface  like bulging veins which converge, on the outside, in large orifices (osculations) through which the food enters. Their reproduction is oviparous and they release into the water their little fertilised eggs, which then turn into autonomous larvae. These larvae swim to distant places where, as they settle on rocks, give rise to the emergence of other fouling sponges.

One curious feature of the Spirastrella cunctatrix is that it contains certain substances, known as lectins, which are bioactive compounds with important pharmacological properties. They are natural proteins with anticarcinogenic qualities.

 Intelligent design in nature is undeniable everywhere you look!