Water canal (aquiferous) system

cliona sp. Exhalant breathing pore (oscule), and the water canal system leading to this pore forced to the surface of this thinly encrusting sponge, Cliona sp.The name ‘Porifera’ means ‘pore-bearing’. Sponges have a differentiated inward flowing and outward flowing water canal system with external pores (ostia and oscula, respectively). These inhalant and exhalant pores are also usually separated in different regions of the body or at different planes on the surface to minimise water contamination.

Some sponges, like the deep sea carnivorous sponges, have lost their water canal system and breathing pores completely (because they have also lost their choanocytes).

Aka sp. excavating a dead coral head Aka sp. completely excavating a dead coral head with the large open breathing tubes (fistules) and terminal exhalant breathing pores (oscules), and microscopic inhalant pores (ostia), scattered on the smaller blind fistules. Monanchora unguiculata Monanchora unguiculata, found in many ports and harbours in the Indo-west Pacific, thought to be dispersed by human activity such as ships fouling and bilgewater.

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