Several species of gorgonian octocorals occur on deep reefs. Nicella schmitti, shown here, lacks zooxanthellae, but feeds on particulates and small zooplankton that are abundant along walls.

Plating Agaricids are common down to about 200 ft on the Little Cayman walls, in shallower water they tend to form smaller plates with upright ridges. These differences in morphology may be a mechanism to efficiently gather light for their zooxanthellae.

One of the more common deep reef corals on the Little Cayman walls are Mycetophyllia sp. since they prefer low light conditions. In fact, on shallow reefs, Mycetophyllia polyps are often retracted during the day.

Team TZ members conducting a site survey at a depth of 40 feet. The team members are taking notes of what they see along the tape in 10 cm increments and 50 cm on either side of the tape. They recorded all sponges and corals they see which is correlated with position information.

A Hawksbill turtle feeding on a sponge.

Although many of the species found at depth will likely be different than those seen on shallow reefs, some mobile organisms can actually move between shallow and deep reefs. This hawksbill sea turtle feeds on sponges which are common in both deep and shallow reefs.

The precious black corals are also common on the wall faces, rarely above 150 ft depth due to prior harvesting for the jewelry trade.

As light becomes limiting in the deep reef fewer hard corals are able to survive, but many species of soft corals and black corals serve the same functional role as habitat and/or food.

The biodiversity of vertical walls can be impressive, as this photo from the Indo-Pacific region demonstrates.

This lettuce coral (Agaricia sp.) is one of the most common corals on the reefs of Little Cayman. The natural color is light tan, but this colony has dark pigmented areas commonly known as Dark Spot Syndrome. The coral is nestled among bright orange sponges (Ectyoplasia ferox).

Black Band Disease was one of the first coral diseases identified back in the 1970s, and is still one of the most prevalent diseases on reefs worldwide. The disease forms a black band of microorganisms that progresses across the coral surface leaving dead white skeleton behind, like that on this brain coral (Diploria strigosa).

In general, most microorganisms are too small to be seen with the naked eye. However, these tufts of filamentous cyanobacteria form large accumulations of individual microscopic cells that are visible. Cyanobacteria often form large aggregations that produce toxins and are detrimental to marine organisms and humans, collectively called harmful algal blooms.

This blushing star coral (Stephanocoenia mechelinii) is severely affected by Dark Spot Syndrome. Although this syndrome rarely kills corals, it can cause localized mortality of coral tissues, as seen in the center of this colony.

Cyanobacteria are increasingly common on Caribbean coral reefs and are frequently found overgrowing benthic organisms such as this soft coral (Eunicea sp.). Although some cyanobacteria form symbiotic relationships with a host organism, others are detrimental and can cause tissue necrosis and mortality.

Looking up to the shallows from below through a window on the reef provides a glimpse of the reef. Built by thousands of years of coral deposition, these outcroppings serve as homes for many species, including corals, fishes and sponges.

Montastrea cavernosa exhibiting green fluorescence only. These are found everywhere from shallow water to deep.

Monsatrea cavernosa exhibiting orange fluorescence and green fluorescence in the mouth of the polyps.

Mussa angulosa, a single polyp, is showing green fluorescence. This sample was found at 60 to 70 foot depth.

Two examples of the solitary coral, scolymia cubensis, found at a depth of 150 feet. The one on the left is showing red and green fluorescence pattern that differs from the one on the right.

A hermit crab found at the steps of the Little Cayman Research Center.

One of the earliest rebreather designs. In 1680, Giovanni Borelli envisioned a diver carrying a large bag of air from which the diver breathed as necessary.

A diver explores the vertical distribution of corals on a Pacific wall.

Snorkler off the Harbor Branch ship SEWARD JOHNSON enjoying the western Bahamas reef environment.

Brain coral and algae. White carbonate sands, shallow waters, and coral rock must tend to attenuate colors as corals and overall environment much less colorful than many other coral reef environments.

Yellow sea fan, algae, and fire coral. Sea fans are a type of gorgonian coral.

Yellow sea fan with flamingo tongue cowry.

Sea rod gorgonian coral with polyps extended, fire coral in right background, trumpetfish (Aulostomus maculatus) camouflaging self by blending in with sea rods.

Sea rod gorgonian coral with polyps extended and trumpetfish (Aulostomus maculatus) camouflaging self by blending in with sea rods.

Snorkelers over massive brain coral.

Massive brain coral showing distinctive patterning. See reef3894 for scale.

Christmas tree worm on massive brain coral see reef3894 and reef 3895 for scale.

Flamingo tongue cowrie on greenish-yellow sea fan. Sea fans are gorgonian corals.

Green sponge

Black coral branches on white carbonate sediment background.

Fire coral.

Fire coral

A long empty queen conch shell with small tube worms colonizing its insides.

Yellow gorgonian coral sea fan

Cowrie shell

One Tree Reef. Crab.

One Tree Reef. Crab.

One Tree Reef. Crab.

Heron Island. Intertidal crab.

One Tree Reef. Crab.

One Tree Reef. Shrimp.

One Tree Reef. Shrimp.

Heron Island. Snails congregating at low tide to prevent drying out

Heron Island. Intertidal chiton.

Heron Island. Intertidal worm with numerous feeding tentacles

Heron Island. Intertidal snail.