Yellow Tube Sponge

Appearance

Colour: Bright yellow in life, turning characteristically dark greenish blue-black when taken out of the water, discolouring one's fingers. In alcohol, the black colour extends into the alcohol and also blackens labels to the point of becoming illegible.
Shape, size, surface and consistency: Massive base from which issue irregular tubular digitations. These digitations are 3-4 cm high, 1-2.5 cm in diameter, and end in a flattened top in the center of which is an oscule with an iris-type of diaphragm. The surface of the basal mass as well as the tubes frequently bare thin long solid "fistules" of variable length. The surface is slippery to the touch and irregularly covered with small conules. Consistency relatively firm, somewhat rubbery.
Spicules: Absent.
Skeleton: Fibroreticulate, without distinction in main and secondary fibres, forming irregularly rounded three-dimensional meshes of up to 3 mm in diameter. The conules at the surface are formed by short blind-ending fibres. The fibres of 80-150 µm in diameter are cylindrical, with a well-developed striated bark and a wide central pith of 30-70 µm in diameter (Aplysina aerophoba fibre). The pith is visible in transmitted light as a dark brown to black central mass in an amber coloured spongin envelope.

Naming

Species Names
Parent
Aplysina Nardo, 1834
Orig. name
Aplysia aerophoba Nardo, 1833
Synonymised names
Aplysia aerophoba Nardo, 1833
Aplysina carnosa Schmidt, 1862 (junior synonym)
Verongia aerophoba (Nardo, 1833) (genus transfer)

Distribution

When diving in the Canaries it is very common. There is hardly a dive where you do not swim past it.
Its distribution area extends from the Mediterranean Sea over close by areas of the Atlantic. It is found on the Spanish and Portuguese coast, around the Azores, Madeira, the Canary Islands, Cape Verde and in the Gulf of Guinea.

Behavior

The Yellow Tube Sponge forms large colonies.

Habitat

Aplysina aerophoba lives on a solid ground, in depths down to 20m. It is more likely to ne found in areas exposed to direct sunlight.

Reproduction

Fertilization takes place in the interior of the Yellow Tube Sponge. The young larvae are discharged through the outflow opening and settle in the early summer to create a new colony.

Food

Its diet consists of zoo- and phytoplankton.

Defense

It produces homogentisic acid to ward off predators. This does not work with the Yellow Umbrella Slug. This feeds exclusively on Aplysina aerophoba, stores its poison, and by this also protects itself against predators.