Corals as Colonies – Colony Surface
The individual coral animal is called the polyp. This simple sac-like animal sits in a skeleton cup made of calcium carbonate, called a corallite. Together the tissue and the skeleton are called the corallum or coralla (plural). The following article discusses the space between the corallites and polyps: the surface of the colony. If you want more information on the corallite or polyp key terms check out the Corals as Individuals articles.
Surface of the Colony – Key Terms
Individual corallites may be separated by a section of skeleton with overlying tissue. Structures that develop in this area are extremely useful when trying to separate corals with similar looking corallites.
- links inside these captions for more info.
Hover over the main image to pause slideshow." title="entry5-new" width='170' height='135' />
While the skeleton between corallites within a colony is known as coenosteum." title="Acropora article Coral Finder pages" width='170' height='135' />
- colony margin - the genus Mycedium." title="Lizard March 2009 (c) Russell Kelley IPCF" width='170' height='135' />
- hoods of skeleton over the corallites are characteristic of the genus Stylophora." title="slide5-3" width='170' height='135' />
- Monticules(or hydnophores) are conical bumps found on the surface of corals of the genus Hydnophora." title="slide5-4" width='170' height='135' />
- valleys & ridges - the genus Oulophyllia." title="CFT" width='170' height='135' />
- Ridges of skeleton can be found on the colony surface independent of corallite wall formation - the genus Pavona." title="slide5-6" width='170' height='135' />
- skeletal ornament - e.g. beads on the coenosteum between corallites in the genus Echinopora." title="slide5-7" width='170' height='135' />
- Verrucae are mounds of skeleton on the colony surface that are often covered in corallites - the genus Pocillopora." title="Lizard March 2009 (c) Russell Kelley IPCF" width='170' height='135' />
Using Surface Characteristics to ID Corals
As with any aspect of coral morphology, it is unwise to rely on any one characteristic when identifying a coral. But examination of the structures on the coenosteum is a useful step on the identification pathway. Below is one example of how knowledge of colony surface structures can help with identification:
Echinopora vs. Oxypora
Both of these genera form thin plating colonies in the form of vases or tiers. Superficially they are similar and may initially be difficult to separate. However, the surface of Echinopora is beaded, whereas colonies of Oxypora have a rougher more ragged look to them. These differences may not sound significant but the following close up photos clearly show that examination of the characteristics of the colony surfaces would allow successful identification.
(Photos of echinopora and oxypora close up)
Veron, J. E. N. (2000). Corals of the World. Melbourne: Australian Institute of Marine Science.