Suberites domuncula

Content sourced from Wikipedia, licensed under CC BY-SA 3.0.

Suberites domuncula is a sea sponge in the family Suberitidae. It contains suberitine, a toxin that can harm animals and kill fish, though hawksbill turtles eat it.

There are two accepted subspecies: Suberites domuncula domuncula and Suberites domuncula latus. The name Suberites latus was once described as a separate species but is now considered a subspecies.

Habitat and relationships: This sponge often lives on shells used by hermit crabs, and at least 13 species of hermit crabs have been found with it. It can also attach to shells of live snails and to the carapaces of crustaceans.

Body structure: The sponge’s skeleton is mainly made of spicules. The main megascleres are monactinal tylosyles and some diactinal oxeas. It has a visible osculum where water exits. Spicules are formed with the enzyme silicatein, which builds silica, and silicase helps break down silica. Spicules can reach up to 450 micrometers long, with an axial canal about 0.3–1.6 μm wide and lamellar layers up to 1 μm thick. Silicatein is found on the spicule surface and inside the spicule’s axial filament. In Demospongiae, a collagen-like cement helps hold the spicules together.

Lifestyle: Sponges are filter feeders, drawing water through a network of canals. They host bacteria. Suberites domuncula produces a bacterial quorum sensing molecule that can influence the sponge’s immune responses and increase genes related to phagocytosis, helping the bacteria live with the sponge. The sponge can distinguish its symbiotic bacteria from other microbes.

Reproduction and development: Suberites domuncula reproduces both sexually and asexually. Asexual reproduction forms gemmules—groups of archeocytes wrapped in a collagen coat—that survive harsh conditions and hatch later. Sexual reproduction releases free-swimming larvae.

Genetics and development: The sponge has development-related genes such as Brachyury and Wnt signaling for cell communication and patterning. It also has membrane-associated guanylate kinase and a tetraspan receptor. When single cells separate, they can form primmorphs—small clusters that can quickly form spicules and show regenerative abilities.

Defense and chemistry: This sponge has antimicrobial activity and produces suberitine, a toxin. It hosts bacteria that produce antibacterial compounds, and it also has its own antibacterial proteins to defend against microbes.