Definition. A fibroblast is a cell that manufactures and maintains connective tissue, the structural framework that supports the organs of all animals. Fibroblasts secrete fibrous proteins and ground substance, which together form the extracellular matrix that is the basis of connective tissue. fibroblast is a cell that manufactures and maintains connective tissue, the structural framework that supports the organs of all animals.
Therefore, there is very little chlorophyll in these tropical waters, keeping them clear. (As an aside, corals are symbioses where phytoplankton have evolved to survive in nutrient-poor tropical waters by living inside the bodies of the corals and obtaining nutrients directly from the waste products of the corals.
The Weddell Sea has been deemed by scientists to have the clearest water of any sea. Dutch researchers from the German Alfred Wegener Institute, on finding a Secchi disc visible at a depth of 79.86 metres (262 ft) on October 13, 1986, ascertained that the clarity corresponded to that of distilled water.