as bryozoans or sea squirts from growing on or near them, making sponges very effective competitors for living space. One of many examples includes ageliferin. A few species, the Caribbean fire sponge Tedania ignis, cause a severe rash in humans who handle them. Turtles and some fish feed mainly on sponges. It is often said that sponges produce chemical defenses against such predators. However, experiments have been unable to establish a relationship between the toxicity of chemicals produced by sponges and how they taste to fish, which would diminish the usefulness of chemical defenses as deterrents. Predation by fish may even help to spread sponges by detaching fragments. However, some studies have shown fish showing a preference for non chemically defended sponges, and another study found that high levels of coral predation did predict the presence of chemically defended species. Glass sponges produce no toxic chemicals, and live in very deep water where predators are rare. Predation Sponge flies, also known as spongilla-flies (Neuroptera, Sisyridae), are specialist predators of freshwater sponges. The female lays her eggs on vegetation overhanging water. The larvae hatch and drop into the water where they seek out sponges to feed on. They use their elongated mouthparts to pierce the sponge and suck the fluids within. The larvae of some species cling to the surface of the sponge while others take refuge in the sponge's internal cavities. The fully grown larvae leave the water and spin a cocoon in which to pupate. Bioerosion The Caribbean chicken-liver sponge Chondrilla nucula secretes toxins that kill coral polyps, allowing the sponges to grow over the coral skeletons. Others, especially in the family Clionaidae, use corrosive substances secreted by their archeocytes to tunnel into rocks, corals and the shells of dead mollusks. Sponges may remove up to per year from reefs, creating visible notches just below low-tide level. Diseases Caribbean sponges of the genus Aplysina suffer from Aplysina red band syndrome. This causes Aplysina to develop one or more rust-colored bands, sometimes with adjacent bands of necrotic tissue. These lesions may completely encircle branches of the sponge. The disease appears to be contagious and impacts approximately 10 percent of A. cauliformis on Bahamian reefs. The rust-colored bands are caused by a cyanobacterium, but it is unknown whether this organism actually causes the disease. Collaboration with other organisms In addition to hosting photosynthesizing endosymbionts, sponges are noted for their wide range