1. Identifying AGRRA Corals: Part 1 Mound and Boulder Corals
© K. Marks
Revision: Judith Lang 1

2. For images used in Part 1, our special thanks to:
Images in this presentation are Copyright © by Ken Marks, New World Publications and by other photographers. Copyright © Ocean Research & Education Foundation
Permission is granted to use this Powerpoint presentation for educational purposes with the AGRRA Program and, with attribution, for other valid educational purposes. All other uses are strictly prohibited.
For images used in Part 1, our special thanks to:
B. Beck, I. Drysdale, B. Grayson, P. Humann, J. Miller,
C. Rogers, C. Sheppard, J. Shulke, E. Shinn, R. Steneck, T. Turner

3. Stony Corals
Stony corals have soft polyps above a stony (calcareous) skeleton. Most reef-building corals form colonies of interconnected polyps.
The shapes, sizes and colour of the polyps and colonies are used to help identify corals.
expanded polyps
partially contracted polyps
© C. Sheppard

4. separated + connected polyp walls
Coral Skeletons
round
© G. Shinn
separated polyp walls
long ridges
and valleys
connected polyp walls
short, reticulated
ridges & valleys
elliptical &
Y-shaped
separated + connected polyp walls
The shapes and sizes of polyps are also visible in their underlying skeletons.
Septa are
conspicuous vertical partitions in the polyp wall.

5. What to Look for Underwater
Adapted from P.R. Kramer
Colony shape – massive (= mound, columnar, heavy plates), crust, plate, branching
Colony size range – small to big
Colony surface – bumpy, smooth, ridged
Polyp size – small to big
Polyp shape – round, elliptical, irregular, Y-shaped
Polyp colour – brown, tan, yellow, olive, green, red
Septal shape – fat, thin; smooth, toothed
What to Look for Underwater

6. The stony corals illustrated here are limited to species found in the wider Caribbean at depths (<20 m) typical of most AGRRA surveys.
The names of some of these corals are changing as a result of modern research. More taxa are added as we gain underwater photographs of species that are rare and/or of geographically limited distributions. Expect periodic updates!
Photographers who can enhance this collection are encouraged to contact Judy Lang at: or
For each species: (# in m and ft) = maximum colony size
AGRRA Coral Species

7. Coding Corals in AGRRA Surveys
Use the CARICOMP-based coral codes.
The coral code for a genus (or occasionally a species complex) is the first 4 letters of its genus name and should be used whenever you are unsure of a coral’s species identity: ORBI = Orbicella
The coral code for a species is the first letter of the genus name followed by the first 3 letters of its species name: OFAV = Orbicella faveolata
Codes are shown before names appear on the introductory slide for species that are commonly recorded in AGRRA surveys.

8. the Orbicella annularis complex on the basis of recent molecular
The Montastraea annularis complex of species (annularis, faveolata, franksi) has been reclassified as
the Orbicella annularis complex
on the basis of recent molecular
and morphological analyses. Montastraea cavernosa retains this genus name. See Budd et al., 2012
(reference given on final slide).

9. Orbicella faveolata OFAV
© K. Marks
OFAV
small, round polyps with exsert walls (= protruding “outies”) in
mounds with “skirted” (platy) edges, or thick plates
greens, browns, grey; may fluoresce
can grow very tall and/or wide
(to ~ 4-5 m/12-15 ft)
© C. Rogers
Close-up

10. Orbicella faveolata OFAV
surfaces smooth, ridged or with bumps aligned in vertical rows
© R. Steneck
shallow/high light
deep/low light
colonies flatten in shade or deeper water
© K. Marks
© B. Grayson

11. Orbicella annularis OANN
© K. Marks
small, round, exsert polyps are alive at the tops of columns
thick plates at colony sides or bases under low light conditions
light brown or yellow-brown
large colonies (to ~ 3-4 m/9-12 ft)
© R. Steneck

12. Orbicella annularis OANN
© C. Sheppard
columns may topple and scatter during storms if their bases are narrowed by bioerosion

13. Orbicella annularis OANN
How differs from O. faveolata:
subdivides to form columns, with basal plates under low light conditions
live polyps on well-illuminated column tops lack a skirt-like edge
lighter tissue colours
© K. Marks

14. Orbicella franksi OFRA
© K. Marks
irregular bumps with large, exsert polyps that are pale or lack zooxanthellae (can see skeleton below)
large polyps along colony margin
irregular mounds, crusts or thick plates
(to ~ 3-4 m/9-12 ft)
aggressive spatial competitor

15. Orbicella franksi OFRA
© T. Turner
deep/low light:
thick, lumpy plates
shallow/high light: irregularly shaped mounds
© K. Marks

16. Orbicella franksi OFRA
How similar to O. faveolata:
have bumps on large mounds, crusts or thick plates
How differs:
larger polyps overall
polyps on bumps are even bigger, irregularly shaped, and often lack zooxanthellae
more aggressive as a spatial competitor
© K. Marks
Orbicella franksi OFRA

17. Orbicella franksi OFRA
© R. Steneck
How similar to O. annularis:
can form large columns or thick plates
How differs:
enlarged polyps in irregular bumps can lack zooxanthellae
polyps along growing margins are enlarged
more aggressive as a spatial competitor
Orbicella franksi OFRA

18. Which is Which? O. annularis O. franksi O. faveolata OANN OFRA OFAV
© K. Marks
© K. Marks
O. annularis O. franksi O. faveolata
OANN OFRA OFAV

19. Complications! Some colonies look like “intermediates” of
O. franksi, O. annularis and O. faveolata.
If unsure of species identity, code as:
Orbicella ORBI
“In general, the genetic and morphological data suggest
a north to south* hybridization gradient, with evidence
for introgression strongest in the north. However,
reproductive data show no such trend, with intrinsic
barriers to gene flow comparable or stronger in the
north.” See Fukami et al., 2004 (reference given on final slide).
*north to south = Bahamas versus Panama

20. Solenastrea bournoni SBOU
© K. Marks
SBOU
polyps separated by a smooth inter-polyp surface
cream to light brown;
polyps are slightly darker than the inter-polyp spaces
smooth or irregularly shaped mounds
(usually to ~ 50 cm/20 in)
1 m !

21. Solenastrea bournoni SBOU
© K. Marks
How differs from O. franksi:
smooth inter-polyp surfaces
bumps on mounds lack enlarged, colourless polyps
lighter colours with distinctly darker polyp centers
smaller colonies
when fully grown

22. Which is Which?
© K. Marks
O. franksi S. bournoni
OFRA SBOU

23. Solenastrea hyades SHYA
How similar to S. bournoni:
light colours
polyps with distinct walls
(to ~ 60 cm/2 ft)
How differs:
larger polyps
irregular lobes above
an encrusting base
© P. Humann
SHYA

24. Montastraea cavernosa MCAV
large, round, exsert polyps
brown, yellow-brown, green or grey;
sometimes fluorescent colours
(to ~ 3 m/9 ft)
© K. Marks
MCAV
Close-up
© J. Miller

25. Montastraea cavernosa MCAV
shallow/high light: mounds or columns
© K. Marks 25

26. Montastraea cavernosa MCAV
© T. Turner
deep/low light: flattened, massive plates or crusts
© K. Marks 26

27. Montastraea cavernosa MCAV
© K. Marks
Fluorescent proteins in the polyps produce the greenish or orange-red fluorescence that is sometimes seen under natural illumination, especially at depths > 3m/10 ft (see Oswald et al., 2007, reference given on final slide).
natural light strobe light
© B. Grayson

28. Dichocoenia stokesi DSTO
very exsert, round, elliptical, elongate, or Y-shaped polyps
cream, yellow, or brown
mounds or irregular shapes
(to 50 cm/18 in)
© K. Marks
DSTO
Close-up 28

29. Dichocoenia stokesi DSTO
© K. Marks
How differs from M. cavernosa:
polyps are much more variable in shape
septa on vertical (not sloping) walls are more distinct
lighter colours
fully grown colonies
are smaller
Close-up 29

30. © K. Marks
Dichocoenia DICH
Colonies with flattened plates, and many smaller round polyps, have been called Dichocoenia stellaris.
Their identity, and that of columnar or irregularly shaped “intermediates” with flattened bases, is unclear. 30

31. What are These? These are all called: D. stokesi DSTO! © K. Marks
© B. Beck
© K. Marks
These are all called:
D. stokesi
DSTO!

32. Favia fragum FFRA
somewhat exsert, round-elongated polyps (some Y-shaped)
septa have small teeth (see next slide)
pale yellow to brown
small mounds
(usually to ~ 10 cm/4 in)
FFRA
© K. Marks

33. Favia fragum FFRA How similar to D. stokesi:
© K. Marks
Favia fragum FFRA
How similar to D. stokesi:
exsert, round-elongated polyps, some are Y-shaped
similar colours
How differs:
polyp walls protrude far less
polyps are less separate
septa with teeth on summits and inner sides
fully grown colonies are smaller

34. Which is Which? D. stokesi M. cavernosa F. fragum DSTO MCAV FRA
© K. Marks
D. stokesi M. cavernosa F. fragum
DSTO MCAV FRA

35. Siderastrea siderea SSID
© K. Marks
SSID
small, sunken polyps (“innies”) with very
thin septa
uniform colours: grey, yellow-brown to brown
rounded mounds
(to ~ 2 m/6 ft)
© J. Shulke

36. Siderastrea siderea SSID
© K. Marks
smaller colonies may be encrusting
some pale or bleached colonies are fluorescent 36

37. Siderastrea radians SRAD
sunken “pinched” polyps (“innies”) with
thick septa
pale polyp walls, centers dark
crusts, low mounds or unattached nodules
small (to ~ 30 cm/12 in)
SRAD
© K. Marks
Close-up 37

38. Siderastrea radians SRAD
© K. Marks
Siderastrea radians SRAD
How differs from S. siderea:
septa are fewer and thicker
“pinched” polyps, some elongate, and with darker centers
fully grown colonies are smaller
and flatter 38

39. Which is Which?
© P. Humann
Close-up
S. siderea S. radians
SSID SRAD

40. Which is Which?
© K Marks
Close-up
S. radians S. siderea
SRAD SSID

41. Stephanocoenia intersepta SINT
© K. Marks
SINT
round, sunken polyps (“innies) with thick septa
brown colour is most intense
in polyp centers; appear
to “blush” when polyps
contract
thick crusts, irregular
mounds
(to ~ 1 m/3 ft) 41

42. Stephanocoenia intersepta SINT
How similar to
Solenastrea bournoni:
small, round polyps with light brownish colours that are most intense in polyp centers
How differs:
sunken (not protruding) polyps
crusts and low mounds have relatively smooth surfaces without large bumps
© K. Marks 42

43. Stephanocoenia intersepta SINT
How similar to
Siderastrea radians:
sunken polyps with dark polyp centers
How differs:
“blushes” when tissues contract
no “pinched” polyps
larger crusts and mounds when fully grown
© K. Marks 43

44. Which is Which? S. intersepta S. radians S. bournoni SINT SRAD SBOU 44
© K. Marks
S. intersepta S. radians S. bournoni
SINT SRAD SBOU 44

45. Porites astreoides PAST
tall, thin polyps look “fuzzy” when expanded
“lumpy” mounds or plates
“unusual” shape or colour combinations can occur even within a single coral!
(to ~ 1 m/3 ft)
Close-up
© C. Sheppard
PAST
© K. Marks
© I. Drysdale
PAST
© K. Marks

46. Porites astreoides PAST
shallow: usually lumpy mounds and yellow, yellow-green or olive
© C. Sheppard
© K. Marks
deep: usually thick crusts, lumpy or flattened plates and grey or brown

47. References
Budd, A.F., H. Fukami, N.D. Smith and N. Knowlton Taxonomic classification of the reef coral family Mussidae (Cnidaria: Anthozoa: Scleractinia). Zoolgoical Journal of the Linnean Society 166:
Fukami, H., A.F. Budd, D.R. Levitan, J. Jara, R. Kersanach, and N. Knowlton Geographic differences in species boundaries among members of the Montastraea annularis complex based on molecular and morphological markers. Evolution 58:
Oswald, F., F. Schmitt, A. Leutenegger, S. Ivanchenko, C. D’Angelo, A. Salih, S. Maslakova, M. Bulina, R. Schirmbeck, G. Nienhaus, M. Matz and J. Wiedenmann Contributions of hosts and symbionts pigments to the coloration of reef corals. FEBS Journal 274: