Just Stop and Snorkel

Tilloo Cut–East side of Cooper Jack’s Cay:   North End of Tilloo Cay, Abacos, Bahamas,  N26° 29.851′  W76° 59.069′  Depth- 0-5′

We had just left anchorage at Tilloo Cay and were headed north to our next dive site. Our guest looked over at a group of rocks making up Cooper Jack’s Cay as we were passing Tilloo Cut and said out loud, “I wonder what’s over by those rocks”.  Luckily, an anchorage was nearby just west of Tahiti Beach so we dropped the anchor and got into the dinghy. The west side of the island was disappointing. Sand was piled up against the rocks making it too shallow and sediment covered for any growth. We motored over to the eastern side, in the inlet itself, and found a shallow hardbottom area covered with Elkhorn, Brain, Star, and Fire corals.  It was late in the afternoon, low tide and we were not able to dive long enough (what’s long enough?). We figured that high tide would be a better time when we wouldn’t have to worry about scraping our bellies on the coral. High tide was early the next morning and we had a lovely snorkel and confirmed that high tide was the time to visit. We dove this right before and after the tide switch so there was little current.  Mid-tide and wind could make this site difficult but it is well worth it to wait for good conditions.

I love to see large colonies of Elkhorn Coral (Acropora palmata).  In many places it has been decimated by disease and is considered threatened everywhere it grows.  Elkhorn fronds characteristically splay out horizontally at the surface of the water at low tide.  Schools of fish are always hanging around.  Here we have some grunts and some black and yellow striped Sergeant Majors (Abudefduf saxatilis).
Another shot of a large Elkhorn Colony.  Elkhorn likes to grow in the shallows with heavy current and/or wave action.  There is a small colony of Blade Fire Coral to the right of the Elkhorn.
We saw all the different forms of Elkhorn coral at this site.  This is the scroll form.
Elkhorn coral grows quickly, putting on 2-4″ per year.  It is a major hermatypic (reef-building) coral in shallow water.
We also saw this Elkhorn-Staghorn hybrid.  At one time, this was thought to be a separate species but genetic work found it to be a cross between the two species.  It is highly variable in form.  This one is branched at the ends of the fronds.
On many of the Elkhorn colonies you will see tiny pinwheels of color.  These are Miniature Christmas Tree Worms (Spirobranchus polycera).  The worm’s body lives in a tube that is overgrown by the coral.
The colorful gills breath and filter food particles from the water.  The double spiral gills are about 1/2″ across and can be withdrawn into the tube in case a hungry fish takes interest.   On the two center individuals you can see the white operculum, which is a spiny door that shuts the worm’s tube when it withdraws.  This close-up also shows the tiny corallites and polyps of the coral.

There is very little of the larger green and brown algaes here probably due to current and wave action.  Some of the rocks appear bare but, if you look closely, you will find they are encrusted with pink Reef Cement, a coraline red algae. Look closely among the coral and rocks for fish and invertebrates.

Elkhorn Coral (background), Blade Fire Coral (left front), gorgonians (center) and purple sea fans (right center) create habitat for large schools of assorted grunts.  Most of these are Smallmouth Grunts (Haemulon chrysargyreum), which have horizontal yellow lines (front center).   There is one French Grunt (Haemulon flavolineatum) next to the Smallmouth Grunt to the right of the gorgonians. The grunts with a black stripe on their tails are Bluestriped Grunts (Haemulon sciurus).  Pink Reef Cement, a coraline algae, encrusts rocks where larger algaes have not taken hold.
These Bluestriped Grunts (Haemulon sciurus) are having a dispute.  No harm done, they energetically show each other their bright red mouths, maybe push a little, then go their separate ways.
Bill found several colonies of Pillar Coral (Dendrogyra cylindrus). This is an uncommon relative of the brain corals and it’s always a surprise to find it.
The Pillar Coral Polyps are usually fully expanded during the day giving the colony a furry look.  There are always several other organisms living with it.
I could barely make out the body and legs of this spider crab nestled down among the pillars.
Only the blue eyes hint that this 1″ juvenile will grow up to be a Blue Tang (Acanthurus coeruleus).
A hole, surrounded by green, brown and red algae, in the dead part of the Pillar Coral is home for this pair of Sharknose Gobies (Elacatinus evelynae).
Blade Fire Coral (center, right background, and left front corner) is sometimes mistaken for Elkhorn because it is orange with white tips.  When they are next to each other you can see that they are quite different.  The fire coral grows erect and is thinner.  It also has a smooth surface where the Elkhorn Coral has a rough surface.  The bushy growth up front is coraline red algae.
Branching Fire Coral (Millepora alcicornis) is abundant here.  Much of it overgrows sick or dead gorgonians.
Fire Coral can take many forms.  This one grows like blade but has more branches.  It has not been determined whether the different forms are different species, hybrids, or just variations of one species.
You might spot the electric blue dots of a juvenile Yellowtail Damsefish (Microspathodon chrysurus) between the fire coral blades as they dart around.  It is also known as the Jewel Fish for obvious reasons.  This individual is about 3/4″ long and will not have a yellow tail until it is grown.
These Mat Zoanthids (Zoanthus pulchellus) were found in another fire coral colony. Zoanthids are similar to anemones in that they are polyps without a hard skeleton.  The polyps overgrow the substrate in a connected mat.  The red blotch in the foreground is an out-of-focus Miniature Christmas Tree Worm, also commonly seen on the fire coral.
These Strawberry Tunicates (Eudistoma sp.) were nestled in between the blades of the fire coral. This species is a colonial tunicate where the individual animals are imbedded in a matrix called the tunic. Each individual has an incurrent and excurrent siphon that provides a water flow through the body for gas exchange and food.

The area surrounding the Elkhorn reef is low relief hardbottom dotted with small reefs and coral heads.

Coral heads are patchy and scattered on hardbottom.  Right of #1-Blade Fire Coral; #2-young Elkhorn Coral growing from a broken frond; left of #3-Lobed Star Coral; below #4-Symetrical Brain Coral, below #5-sea fan gorgonian; #6-rock covered with pink Reef Cement algae; below #7-dead coral head; above #8-Mustard Coral, right of #9-sea rod gorgonian.
The more delicate Elkhorn and Blade Fire Coral are often broken up by storms.  These corals have the ability to grow from broken off pieces.  Waves pretty much roll over more substantial forms like these brain corals, and Sea Fans are flexible enough to bend without breaking.  During strong hurricanes, though, even these corals can be uprooted or broken.  Did you notice the light spot on the Sea Fan?  Look at the next picture to see what it is.
The orange dotted mantle of the Flamingo Tongue (Cyphoma  gibbosum) covers the white or tan shell of the snail.  The flattened branches of the sea fan the Flamingo Tongue is feeding on are characteristic of the Venus Sea Fan (Gorgonia flabellum).
Sun Anemones (Stichodactyla helianthus) carpet the bottom in some places.  These four anemones probably came from one that reproduced by division.  Anemones of different clones will often sting each other causing one to creep away.  Anemones can move slowly by gliding on the basal disk that is attached to the substrate.  They also can detach completely and roll around with the waves until they find a better place to attach again.  Also in this picture is some Symmetrical Brain Coral and some Blade Fire Coral.  The Blade Fire Coral to the upper right of the far right anemone is covered with Miniature Christmas Tree Worms.
The cracks, crevices and holes in the hardbottom give shelter to juvenile fish.  Juvenile Bluehead Wrasses (Thalassoma bifaciatum) have a thick horizontal black stripe.  A Blue Chromis (Chromis cyanea) in the center and a juvenile Spanish Hogfish (Bodianus rufus) hang around a small pothole. The largest fish here is less than 1″ long.
A pair of Banded Butterflyfish ( Chaetodon striatus) swim among Symmetrical Brain Corals.  Most brain corals grow in dome shapes or spheres.
Knobby Brain Coral (Pseudodiploria clivosa) often encrusts the bottom with amorphous knobs sticking up here and there.  The polyps are often expanded during the day.
Mustard Hill Coral (Porites astreoides) is seen at just about every shallow water environment.  The polyps are expanded and the gills of several Miniature Christmas Tree Worms dot the surface.
A patch of Lobed Star Coral, gorgonians and dead coral attract several species of fish.  Grey fish on the right are Brown Chromis (Chromis multilineata), fish in the middle with horizontal black and white stripes are Striped Parrotfish (Scarus iseri), long yellow and white fish with dark horizontal stripe are Bluehead Wrasses (Thalassoma bifaciatum) and vertical black striped fish are Sergeant Majors.
A Whitespotted Filefish (Cantherhines macrocerus) swims by a gorgonian.
A hole under the coral heads is a great place to find a Spotted Moray Eel (Gymnothorax moringa)

Again we were rewarded when we just stopped and got in the water.

Information about Elkhorn Coral was obtained at: http://www.fisheries.noaa.gov/pr/species/invertebrates/coral/elkhorn-coral.html

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