Which animals can live inside the canals and cavities of animal sponges?

Various animals inhabit the canals and cavities of sponges, utilizing them for shelter, nourishment, or as a site for intimate parasitic or predatory associations. These organisms include:

• Crustaceans: Various species, including shrimps of the genus Spongicola, which may become trapped within the rigid skeleton of certain sponges for life.1
• Worms: Both nematode and polychaete worms.1
• Echinoderms: Ophiuroid echinoderms, commonly known as brittle stars.1
• Mollusks: Bivalve mollusks.1
• Parasites: Cyclopoid copepods are notable marine parasites, while freshwater sponges may host rotifers, mites, and the larvae of spongillaflies.1

The number of organisms residing within a single sponge can be remarkably high; for instance, thousands of individuals representing various species have been documented within the Caribbean sponge Spheciospongia vesparia.1