Friday, April 11, 2014

Camouflage in the Underwater World – By Emily

Gaze at a reef and you’ll see a vivid habitat- tan fire coral, purple gorgonians, red lacy-looking lionfish, and millions of other colors and corals. But what is more interesting is what you can’t see… and what’s in clear view telling you “don’t touch me”. In reefs all animals drape themselves in color or camouflage to entice mates, catch prey, or even hide in plain sight. 

Butterfly Fish (Ref 5)
There are many types of camouflage, many of which we have seen in our travels. The most common is coloring that resembles surroundings. Many wrasses and parrotfish are blue or brown to mimic the color of the water or coral. Most young parrotfish look a lot like coral, so that when they move it seems like the coral has come to life. The most amazing example is the frogfish, a creature even I have not seen, but still hope to. One that we have seen is the devil scorpion fish. 

Scorpianfish (Ref 10)
Most of the angelfish and butterfly fish use disruptive coloring to break up their distinct shape and become more like the reef. Non-repetitive designs like spots or stripes may stand out in open water, but they become part of the menagerie of shapes in a reef. Queen and Emperor Angelfish are blue and yellow striped to blend in, and Threespot Flounder have eyes on their body to confuse predators.

Yet other creatures find different ways to hide. Toad fish, stargazers, and rays lie close to the bottom to eliminate their shadow, making them almost invisible to predators; they’re just a lump in the sand. Fish like lizardfishes and garden eels even bury themselves or dig holes. One rare fish that we have seen is the shortnose batfish that looks basically like a pancake with two legs, a tail, and a snoot. Many shells bury themselves in sand; the only giveaway is their track that weaves through the ripples of sand. Wobbegongs are flat and colored to the bottom, and they’re so confident in their camouflage they won’t move unless touched.  

Long Nose Batfish (Ref 4)
The most breathtaking form of camouflage is self-decoration. Hermit crabs carry a heavy shell, Decorator Crabs load themselves with massive amounts of debris, and Carrier Shells glue on shell fragments in a spiral pattern. Many shells are smooth to repel such growths, but others, like the Atlantic Thorny Oyster give lots of protrusions to attract algae and coral. 

Carrier Shell (Ref 6)
Trumpet fish and seahorses display cryptic behavior, mimicking the reef, whether that may be swaying soft corals or waving grasses. Razorfish and trumpetfish are long and skinny to look like a floating branch. Groupers and many other fish stay very still, relying on their coloring to stay inconspicuous. Trumpet fish are the funniest, for when they are approached, they stay very still, only moving to sway back and forth. Suddenly they start to change color and dart away to safety.

Trumpetfish (Ref 8)
What I think of as the best camouflage is changing color; the octopus, flounder, and squid do it well. Octopi not only use it to camouflage, they also use it to hunt. They drift over a patch of coral when they’re dark brown, and then stop and make their webbing white. Fish in the rocks think it’s an opening and dart into the octopus’s hungry mouth. When they’re still they change color rapidly to suit the coral, which is impressive considering they’re colorblind. Once we saw an octopus eating a conch, a few tentacles in and around it, but when he saw us he stopped and hastily changed color, not moving even when we were a few inches away, as if to say, “it’s mine, go away!”

Octopus Eating Conch, can you spot him? (Ref 9)
Open-ocean fish are often silvery or transparent to color themselves like the sea. Moon jellyfish are almost entirely clear; the only giveaway is their faint outline and slight shimmer. Fish like tuna are silvery to reflect light and appear blue from a distance. Some squid illuminate their underside with sparkles so as not to appear as a dark shape when viewed from below.  

Squid (Ref 7)
Some animals have light-colored underbellies because they are "counter-shaded." They are darkest on their backs, which are most often in direct sunlight, and lightest on their undersides, where a predator would see against the sun. An effectively camouflaged prey may appear flat and insubstantial.

Some sea creatures use motion dazzle. Motion dazzle may degrade predators' ability to estimate the prey's speed and direction accurately, giving the prey an improved chance of escape. Motion dazzle distorts speed perception, and is most effective at high speeds; stripes can also distort perception of size (and so, perceived range to the target). One example is a school of moving striped fish, such as razor fish and striped catfish.

Striped Catfish (Ref 13)
Underwater, the most complicated disguise is the art of using depth and color. As you may know, colors disappear with the reds and oranges fading first. Longer wavelengths of reds and oranges are quickly absorbed by the water. Damselfish, angelfish, and wrasses decorate themselves with these colors so that their color fades and blends, with depth, into the colors of the background, blue, green, and yellow dominating. Clouds of angelfish, and damselfish would blend their colors into a collage of multi shaded masses, stripes and spots helping to weave the pattern of the busy reef habitat.  The more fish, the merrier, with such an excess of pattern and color, no one creature stands out. You can easily imagine how a predator would have trouble picking a single fish from a school of similar color, constantly moving.

Anthias Normal (Ref 11)
But, the color so useful in fading away can also be used to stand out. Fish use vivid displays of color to communicate their love to mates… or to warn away unwanted guests. Masters of beauty, Athias, appear drab normally, but erect their dorsal fins and blare their colors to attract a mate. The show doesn’t last for long though, the colorful performance exposing them to great risk from predators. The ability to change color is a class of skin cells
called chromatophores that show color through light manipulation or pigmentation. Chromatophores can instantly mark their bearer as terrifying, invisible, or irresistible.

Anthias Courting (Ref 12)

Some other colorful examples are Stonefish, who use their brown exterior to be invisible, but when frightened, open their colorful pectoral fins to warn off predators, “Stay away, I’m poisonous!”, and cleaner shrimp, who are not only colorful, but at a depth seem black and white, where red turns black.

In the underwater world, those who stand out and stay still clearly have a meaning. Bold colors can advertise danger. Clown fish sit in stinging anemones, lionfish are poisonous, and scorpion fish are too. 

Fire urchins are red, yellow, purple and blue, able to stand out at any depth, and blast the message: toxic. One day I saw a ray that was unfamiliar to me. It was sitting on the bottom innocently covered with sand, and stupid me wanted to see what color it was. I dove down to the bottom and touched it to make it move, since it clearly wasn’t afraid- bad mistake. Zzzzzzt!  I received an electric shock; I later learned it was a lesser electric ray. I never did see its color, but lesson learned, and I didn’t try to touch it again. Just yesterday, we saw an Atlantic Torpedo, able to produce enough electricity to stop a man’s heart. 

Torpedo Ray (Ref 14)
But, if a fish wanted to attract a mate without being seen, how would he do it? To solve this problem Damselfish use reflectors to flash UV signals to communicate with others, and predators can’t see it. A male Squarespot Anthias is red and orange in normal light, at eighty feet is blue and purple, but in UV light is dark with a brilliant white spot, an easily seen signal to others of his kind, but not predators.  



Every creature is exceptional in its own way, a majority amazing in camouflage. Others have found a way to stand out, extraordinary and bathed in color.

Emily

References:
1. en.wikipedia.org/wiki/Camouflage
2. National Geographic  Vol. 209     NO. 5    May 2005
3. Reef Fish Identification, Tropical Pacific
6. http://www.zymoglyphic.org/exhibits/xenophora/images/4.jpg 
7. a-z animals.com  
9. emilygwestonphotography.com 
10. http://www.divevietnam.com/ 
12. www.flickr.com 
14.www.elasmodiver.com 

Wednesday, April 2, 2014

The Exumas

We spent about 5 days in Georgetown.  We never found a lot of Kid boats but it had not changed much since 2009.  They still had an active VHF radio net each morning and plenty of organized activities.  Tom took advantage of the VHF net to advertise to the 300 cruising boats anchored here and unload some used items.  We sold our old back-up dingy, 2 HP outboard motor and all of our paper Caribbean charts to 3 different cruisers.  Here is a pic of our old dingy being towed away…it had no patches but it was almost 10 years old.


We also found the Chat ‘n Chill conch bar was still there and we ordered up 3 salads for a beach snack.  We watched them bring 3 conchs up from the beach, open and clean them and then chop them up (raw) finely with fresh onions, peppers, tomatoes and they drowned it all in lime and orange juice.  I even had them add a little diced habanero hot pepper to mine for some extra zip!  


Man, was that good.  Emily enjoyed petting the tame sting rays that were also enjoying the conch discards.


From Georgetown we moved northwest to Rudder Cut Cay where we took shelter from the wind that would clock from southeast to west to north within 24 to 36 hours before returning to the normal easterly direction.  This happened each time a cold front went through which was happening about every 5 days.  We had to plan our moves to enjoy the south wind while moving north but find good shelter from the clocking winds after arrival.  Because of the limited anchorages giving shelter from the west winds and the sheer number of cruising boats, it was a challenge to find room. 


We saw 3 good sized boats driven hard aground on reefs.  This fellow tried to anchor near me but was convinced (by me) that there was not enough room and anchored elsewhere.  The next morning, he was hard on a reef and was pulled off by the blue salvage vessel.


The water was clear at Rudder Cut Cay.  Kim and Emily Snorkeled each day collecting shells.  We saw an underwater statue here too before moving north to Big Majors & Staniel Cay. Check out the eyes on the milk conch in the photo below.

 

We enjoyed feeding the swimming pigs again and snorkeling Thunderball Cave.  The nurse sharks are still hanging around the dingy dock at the yacht club waiting for handouts.

 


Warderick Wells was our next stop but was a disappointment because we were looking forward to feeding the sugar birds (bannaquits).  During our 2009 stop, the rangers handed out sugar and Emily had swarms of the birds on her tiny hands.  Environmental Nazis have now stopped handing out sugar and they discourage feeding them.  We ignored their idiocy, took out our own sugar and found at least one bird that remembered the good old days with us. 

 

Tom and Emily hiked up towards Boo Boo Hill and Tom slipped on some loose rocks and found a different type of Boo Boo.  Despite a bloody knee we enjoyed the views.


After Wardrick Wells, we stopped at Shroud Cay.  This island was new to us and we enjoyed taking the dingy through the winding mangrove streams all the way to the eastern side and a powder white beach.

 

 

Our last stop in the Exumas was Allen’s Cay.  Although crowded in the main anchorage, we found just enough room to set our hook in southwest Allan’s Cay.  We were all alone with our private white sandy beach. We were a bit anxious as the winds rose to 25 knots and started clocking around.  At two points in this process the stern of Emily Grace was only about 30 feet off the jagged coral coast.  The anchor was dug in hard however and held well.  This was not the first time we were thankful for our oversized 120 lb Spade anchor!

 

The big attraction here is the iguanas.  That same private beach in our cove would swarm with hungry iguanas every time we would come to shore with our table scraps.  Judging from their numbers, they seem to be doing just fine.


From here we will make a short hop northeast to Spanish Wells at the north of Eleuthera before heading up to the Abacos.  These are all new islands to us and we are anxious to see what they have to offer.  Come along.


Tom

Wednesday, March 5, 2014

Bahamas - Thompson Bay, Long Island


Wow what a great place.  There is a really large anchorage here and although shallow, we managed to get pretty far into the north to the edge of the 2 meter deep water to drop the hook.  There is a nice floating dingy dock at Long Island Breeze restaurant and they are very welcoming. The owner, Mike, even runs a VHF net with weather and info for the cruisers.  The restaurant food was not too expensive and we managed to eat several lunches ashore.   


There is a Saturday morning market for some fresh vegetables and baked goods like pumpkin bread and guava rolls.  There are two grocery stores and auto supplies and a few mechanics.  Every one beeps and waves on the road and offers rides.  I found the owner of a SCUBA shop had a garage workshop that rivals mine back home.  He sorted out a broken shower hose by pulling out a good assortment of special fittings and doing a silver solder repair for me.

We did home school, maintenance on the lugger and some varnish work while we were here for about a week.  We had one day of westerly winds that made the anchorage uncomfortable, but mostly it was nice and calm with cool breezes.  One night, the temps dropped to about 75 F and Emily was wearing socks to keep warm!

We heard about some caves near the SCUBA shop, so one day after lunch at Long Island Breeze restaurant, we walked over with two flashlights and a headlamp.  We spoke to owner to access the caves through his property and they were surprisingly large.  We quickly found the entrance and walked in…and in….and in.   



 

The tunnels were winding and must have gone in at least 1000 ft with several side tunnels.  We were enjoying the stalactites and stalagmites until about half way in we saw this fellow coiled up in the dark.   


That was when Kim decided to turn back with Emily in tow. On the way out, they spied this fellow lying on the floor and never stopped to check if it was real or plastic.  


The fearless (clueless) Captain soldered on alone and found the large domed cathedral at the end.  It had to be 50 feet wide and 40 feet tall.


There were bats on the ceiling and several were disturbed by our lights and were dive bombing us (within inches) as we moved through the blackness.  There were hundreds of deep holes in the ceiling and most were filled with bats like little apartments.     


I managed to go back and lure Emily through the entire cave system, but mom decided to stay outside and guard the entrance. 

 

We saw several beautiful formations and saw the tool marks made by others harvesting crystal.  Emily and I looked hard, but never saw any crystals. 


As we neared the exit, we switched off our lights to get the full experience.  

Tomorrow we will head to Georgetown and hopefully find some more kids for Emily.

Tom