Aplysina aerophoba

Aplysina aerophoba is a sponge of the class Demospongiae, order Verongiida and family Aplysindae. It is distributed along the coasts of the eastern Atlantic Ocean, from the Bay of Biscay to the coasts of Mauritania, including the entire Mediterranean Sea and the Canary Islands. It inhabits coastal rocky bottoms, in areas where it receives direct illumination, and therefore its depth range is rather limited, being able to be found up to 15 meters deep at the most. The specific epithet aerophoba, refers to the fact that if any individual of this species is taken out of the water, it immediately loses its normal coloration and becomes bluish.

The color of Aplysina aerophoba is yellow-orange, and it adopts a tubular shape that can reach 10 cm in length and 2 cm in width. In the upper part we find an opening. This species usually forms aggregations of different individuals, which form a colony.

The feeding of Aplysina aerophoba is by filtration of the water column that surrounds them. Through a multitude of small pores throughout its body, it inhales the surrounding water, and by means of specialized flagellated cells, creates the necessary current to generate the water current through its body, and thereby trap small organic particles or bacteria from which it obtains the energy and compounds necessary for growth. All the water that has been filtered by the individual will be expelled through the upper osculum.

Aplysina aerophoba can reproduce both sexually and asexually. Asexual reproduction can occur by budding of an individual in the colony, or by fragmentation. Those fragments of the individual that have been produced by the forces of marine storms have the ability to regenerate a complete individual. As for sexual reproduction, male and female gametes are released into the water, where fertilization occurs and the larva is formed. This will go through a planktonic ciliated larva phase, which after some time will settle to the substrate to give rise to an individual.

The nudibranch Tylodina perversa, feeds on the tissue of Aplysina aerophoba, from which it picks up its yellow color.

It is common to confuse specimens of Aplysina aerophobaa, with specimens of the sponge Aplysina cavernicola. The coloration, shape and texture of both species is very similar. In order to distinguish them we will have to look at the habitat where we have observed them. If, as mentioned above, the place where we observe the sponge is a brightly lit place, we will undoubtedly be facing specimens of Aplysina aerophoba, but if on the contrary we are in shady places such as caves, we will be facing specimens of Aplysina cavernicola.