2. Maze Coral or Is It Rose Coral

Maze Coral Source: http://en.wikipedia.org/wiki/Meandrina_meandrites
Maze Coral (Meandrina, meandrites) Living Sample
Source

Judging from the title of this article, you may have gathered their can be some confusion when 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 was confused by several coral species that I now feel confident about their identities after some head scratching and investigating. Maze Coral and Rose Coral fossil skeletons look very similar at first glance; descriptions explained below which solved the puzzle.

Both species are commonly found in the Bahamas, Caribbean and Florida shores.

Rose Coral Fossil
Maze Coral Fossil (Meandrina, meandrites) Fossil Skeleton

While researching, 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 (half-sphere) plates which fit the description of the one in the photo above; colors tend to be brownish or greyish.

Habitat: A wide range of habitats across the Caribbean, Gulf of Mexico, Bermuda, the Bahamas and Florida occurring at any depth less than 80 meters (260 feet) in reef-environments.

MAZE CORAL CLASSIFCATION

  • Kingdom: Animalia
  • Phylum: Cnidaria (Animal with stinging cells)
  • Class: Anthozoa (Flower like animals)
  • Subclass: Hexacorallia (polygonal 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 one meter (3 feet) across)
  • Species: M. meandrites

3. Rose Coral

Rose Coral (Manicina, areolata) Fossil Skeleton
Rose Coral (Manicina, areolata) Fossil Skeleton
(Shows Cone Shape Underside)

Two Growth Forms of Rose Coral

Rose Coral, Manicina, areolata occurs in two distinct growth patterns making matters of identification even more confusing. The first form consists of semicircular heads with wide, winding valleys and ridges forming irregular furrows; and with irregular cone-shaped undersides. (Shown above in the fossil skeleton photos)

Manicina areolata Source: coral.aim.gov.au
Rose Coral (Manicina, areolata) Living Sample
Source

The other and most common rose corals form elliptical or oval colonies with a long, continuous central valley with several short, side valleys, and lastly, a short stalk underside. (Seen in the living sample and fossil skeleton samples below)

Interesting Behavior

Rose corals are one of only a few corals that can be actively mobile. If a small colony of rose corals gets turned upside down, it proceeds to gorge its stomach with water in order to bloat, and then it jets the water out 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 it finally flips over in an instant. 

Underside: Rose Coral (Manicina, areolata)l Fossil Skeleton
Rose Coral (Manicina, areolata) Fossil Skeleton

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. Larger colonies are more likely to die by smothering in the sediments placing a limit on the size any given colony can grow.

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 aerolata Source: http://reefguide.org/carib/rosecoral.html
Rose Coral (Manicina, aerolata) Living Sample
Source

ROSE CORAL 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

Note: The genusManicina, includes over 10 species, but Manicina, areolata is the only species that survives today. The heyday for Manicina was during the Miocene and Pliocene epochs 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.