Atlantic. Of the latter, five are primarily cold temperate, one 

 (/4 . astreiformis) is found both in temperate and tropical waters, 

 and one (Deltocyathus italicus) is primarily a tropical species 

 with northern limits in the cold temperate region. Only one 

 species, Enaltopsammia profunda, is endemic to the western 

 Atlantic and is most common in the warm temperate region. 



MORPHOLOGY 



The calcareous skeleton of a scleractinian coral, the coraUum, 

 may be composed of numerous individual units producing a 

 colonial corallum or it may be a solitar}' coral with only one unit 

 produced by one polyp. The shape of the corallum of solitary 

 corals is important at the generic and specific levels and is 

 commonly described in geometric terms (e.g., conical, trochoid, 

 cylindrical); shapes of colonial corals are described by branching 

 pattern. 



Corals may be either attached to the substrate or unattached 

 (free), this difference usually being consistent at the species 

 level. If attached, the base of the coral is fu-mly cemented to a 

 hard surface. A solitary attached coral usually has a stemlike 

 pedicel directly above the base (Fig. 1), which supports the 

 calice, the round to elliptical oral surface of the coraUum. The 

 solitary attached coral often reinforces its attachment by 



^PALUS 



COLUMELLA 



PEDICEL 



BASE 



thickening its pedicel, expanding its base, and, in some species, 

 producing anchoring rootlets or adding successive rings of 

 compartmentalized, concentric chambers around the base and 

 pedicel. A solitary unattached coral usually has a flat or bowl- 

 shaped base and lacks the pedicel. The sides or walls of solitary 

 corals and corallites of colonies are termed the theca. This theca 

 may be granular or porcelaneous in texture and often bears 

 longitudinal ridges called costae corresponding to the larger 

 septa. Skeletal deposits formed between individual coralhtes of 

 a colony are called coenosteum. 



The calice of most species is regularly and hexamerally 

 subdivided by radial partitions, called septa. The six largest 

 septa, divide the calice into six equal areas or systems (Fig. 2), 

 and comprise the first cycle of septa. The second cycle also con- 

 sists of six septa which are generally smaller and occur halfway 

 between the first cycle septa. The 12 third cycle septa are formed 

 in each space created by the previous 12 septa. Calices with 6-7 

 cycles of septa (192-384 septa) are known. Septa with the upper 

 edges extending above the theca are termed exsert septa. 

 Sometimes one or several adjacent septa of a calice are extreme- 

 ly exsert and bent over the calice, forming a hoodlike structure 

 called a rostrum (e.g., see figure of Enaltopsammia rosiraia). 

 Small accessory lobes are sometimes present on the inner edges 

 of the septa of certain cycles. These are called pali (singular: 

 palus), or paliform lobes, and are often used as a generic level 

 character. Directly in the center of the calice there is often a 

 structure called a columella, which may appear as a lamella 

 (lamellar), a spongy mass (trabecular), a single rod (styliform), a 

 field of simple or twisted rods (papillose, fascicular), or simply a 

 fusion of the inner edges of the larger septa (rudimentary). The 

 type of columella is often used to distinguish genera and 

 subgenera. 



' SYSTEM 



-Cutaway drawing of hypothetical : 

 raorphological features. 



slitary coral illustrating 



Figure 2. — Diagram of relative sizes and position of septa in a calice 

 containing three cycles (24 septa). Numben refer to the cycle to which 

 the septum belongs; only the upper right system is completely 

 numbered. 



