Comparing Two Starlet Corals

starlet fossil

Starlet Coral Fossil (Click to enlarge for fine details , then arrow back)

Starlet corals remains, not to be confused with star corals, are commonly found off the Caribbean, Florida and Bahama shores. I have two species from the genus Siderastrea. As I’ve mentioned in previous posts, these corals were discovered off Florida’s beaches in the 70’s and 80’s by my mother in law Winkie during family vacations.

Winky and Joe (83')

1983 Winkie Mirto with Son, Joseph (my late mother-in-law and husband)

 

Massive Starlet Coral (Siderastrea, sidereal ) httpcoral.aims.gov.aufactsheet.jspspeciesCode=0614

Massive Starlet Coral (Siderastrea, sidereal )
Source:
http://coral.aims.gov.au/factsheet.jsp?speciesCode=0614

Siderastrea, sidereal, commonly referred to as  Massive Starlet Coral is a very slow growing species that lives to a great age forming large colonies, sometimes, over a meter across. It’s closely related to the Lesser Starlet Coral, Siderastrea, radians. You must look very closely in order to observe their differences!

One way you can tell them apart is by their growth patterns. I’ve provided a comparison chart below. But another interesting way worth mentioning, first, is by observing the environment where they grow, which most people are only able to do through pictures. Nevertheless, unlike the Massive Starlet Coral, the Lesser Starlet Coral often looks as though the colony is  growing under the materials around it.

starlet coral radians httpcoral.aims.gov.aufactsheet.jspspeciesCode=0613

Lesser Starlet Coral (Siderastrea, radians Source: httpcoral.aims.gov.aufactsheet.jspspeciesCode=0613

starlet fossil -

Lesser Starlet Coral (Siderastrea, radians) Fossil

(Click to enlarge for fine details, then arrow back)

starlet fossil - underside

Lesser Starlet Coral (Siderastrea, radians) Fossil Underside

CLASSIFICATION

  • Kingdom: Animalia
  • Phylum: Cnidaria (Animals with Stinging Cells)
  • Class: Anthozoa (Flower Animal)
  • Subclass: Hexacorallia (Polygon Structures)
  • Order: Scleractinia (Modern Stony Corals)
  •  Family: Sideractinia
  • Genus: Siderastrea
  • Species: sidereal and radians

 

 

 

 

COMPARISON CHART 

Massive Starlet Coral (Siderastrea, sidereal)               Lesser Starlet Coral (Siderastrea, radians)

  • Usually Dome Shaped                                                Mostly Encrusting Flat or Uneven Sphere
  • Large Colonies Up To A Meter                              Usually Small Colonies About 1 ft. Across
  • Roundish Corallites (Holes)                                    Somewhat Angular Asymmetrical Corallites
  • Shallow Corallites                                                        Deeper Pitted Corallites
  • Obscure Septa (Ridges)                                             Pronounced Septa (Ridges)
  • Thin Fine Walls Between Septa                             Wider Walls Between Septa
  • Septa Uniformly Separated                                     Septa Separated Unevenly
  • 50 to 60 Septa In Each Corallite                           30 to 40 Septa In Each Corallite
  • Smooth Surface                                                            Pitted Surface
  • Uniform Color                                                              Contrasting Dark Centers
  • Pink, Cream, Brown, Grey                                      Whitish, Grey, Green, Light Brown
  • Depth from 40 to 10 meters                                   Only Shallow Depths 10 meters
  • Not tolerant of tide pools and silt                         Tolerant of tide pools and silt

Maze Coral or Is It Rose Coral

Judging from the title of this article, you may have gathered their can be confusion identifying coral fossils and you would be right. All corals are not single organisms, but rather are a colony of individuals we know as polyps (the jelly like part). The polyps band together and slowly build a calcium carbonate skeleton. Herein lies the physical diversity of corals as each species builds a slightly different style of skeleton.

I feel fairly confident I have several maze coral fossils in my possession inherited from my mother in law, Winkie’s, collection. They are commonly found in the Bahamas, Caribbean and Florida shores where she discovered them lying on the beaches during family vacations in the 60’s and 70’s.

Can you tell the difference between the maze coral and the rose coral below?

Rose Coral Fossil

Maze Coral Fossil

While searching, I realized that maze corals are sometimes lumped together with brain corals or are even called maze brain corals.  The most distinguishing features from other brain corals is that the maze brain coral have thicker convoluted ridges and well defined plates. Also, there is an indentation running along the crest of the walls where the adjoining plates “corallites” meet. Colonies form both flat heads and or hemispherical plates which fits the description of the one in the photo above.

CLASSIFCATION

  • Kingdom: Animalia
  • Phylum: Cnidaria (Animal with stinging cells)
  • Class: Anthozoa (Flower like animals)
  • Subclass: Hexacorallia (corals having parts in multiples of 6)
  • Order: Scleractinia (Stony Skeleton)
  • Family: Meandrininidae (Meandering Colony Corals)
  • Genus: Meandrina (forms massive hemispherical heads or have large flat plates and can grow to a metre (yard) across)
  • Species: M. meandrites
Rose Coral Fossil (Shows Cone Shape Underside)

Rose Coral Fossil
(Shows Cone Shape Underside)

Rose coral, Manicina, areolata,  often have irregular cone shaped undersides and at times consist of a short stalk which can be unattached to the substrate. The most common rose corals forms elliptical or oval colonies (shone below) with a long continuous central valley and several short side valleys.

Colors: Yellowish-brown, tan or dark brown, often with the valleys and walls being contrasting colors. Like most corals, the polyps are only extended at night and are often green.

Manicina areolata Rose Coral Fossil

Manicina areolata
Rose Coral Fossil

Manicina areolata Rose Coral Fossil (Underside)

Manicina areolata
Rose Coral Fossil (slight cone shaped underside)

Interesting Behavior

Manicina areolata is one of only a few corals that can be actively mobile depending if its the colony form.

If a small colony gets turned over it gorges its stomach with water to become bloated, and then jets water from one side at a time. This causes a back and forth rocking motion until the center of gravity shifts, allowing it to rapidly flip upright. The entire process takes a few hours until the final flip occurs in an instant. Larger colonies are more likely to die by smothering in the sediments placing a limit on the size any given colony can grow.

Second Growth Form (Hemispherical)

Manicina, areolata rose coral occurs in two distinct grow patterns making matters even more confusing. The second form consists of semicircular heads with  flattish undersides, winding wide valleys and ridges forming irregular furrows. 

Manicina aerolata Source: http://reefguide.org/carib/rosecoral.html

Rose Coral Manicina aerolata
Source: http://reefguide.org/carib/rosecoral.html

Rose Coral Fossil

Rose Coral Fossil

Habitat: Rose coral Manicina, aerolata is very abundant off the Floridian shores as well as the Bahamas and Caribbean. It prefers shallow, productive, near shore habitats characterized by abundant sediments such as seagrass meadows, or along the fringes of mangrove forests.

CLASSIFICATION

  • Kingdom: Animalia
  • Phylum: Cnidaria (Animals with stinging cells)
  • Class: Anthozoa (Flower Animal)
  • Order: Scleractinia (Stony Skeleton)
  • Family: Faviidae (generally spherical shape and grooved surface which resembles a brain)
  • Genus: Manicina
  • Species: M. areolata

The genus Manicina sp. includes over 10 species, but Manicina areolata is the only species that survives today. The heyday for Manicina was during the Miocene and Pliocene eras between (24 million to 1.6 million years ago). About one million years ago, approximately half the species of reef corals living in the Caribbean became extinct.