Story and Photos by Darelle Snyman
The Caribbean Sea hosts a vibrant tapestry of marine life, but the reef fishes, adorned with the most intricate body patterns and colors, attract our attention. These body adornments are not merely for aesthetic appeal and a way for us to identify these beautiful creatures, highly useful traits as those traits are for us. Color and pattern adaptations form essential tools in their arsenal to interact and survive within their watery home. The stunning array of hues and designs reef fish exhibit play a multitude of roles in their daily lives, from camouflage to courtship and social signaling.
One of the most common reasons for color and pattern adaptations among reef fish is for camouflage. Not all fish want to stand out; many prefer to remain incognito and use color to blend in with their surroundings, either to avoid predators or to ambush unsuspecting prey. Masters at this strategy within the Caribbean Sea include flounders, trumpetfishes, scorpionfishes, and one of my bucket list fish to photograph, the frogfishes. I personally think frogfishes win the award for being the best at camouflage, but a close second would be the spotted scorpionfish (Scorpaena plumieri). They rely on their incredible camouflage ability even more than their venomous nature to pounce on unsuspecting prey. I have been lucky to encounter these sulky looking fish a number of times, and each time I felt extremely lucky that I was actually able to spot them. Their diverse mottled coloring, combined with the fleshy plumes over the eyes and characteristic skin flaps, allows them to blend exceptionally well into their surroundings.
When it comes to possessing chameleon-like capabilities to blend in, we cannot ignore another Caribbean resident, the peacock flounder (Bothus lunatus), named for their iridescent blue spots. These flat fish are able to adjust the color pigments housed in specialized cells, called chromatophores, in their skin to blend in with a remarkable variety of surroundings, from sandy bottoms, coral reefs, to even patterned surfaces. These color changes can happen within a matter of seconds and this blending ability is greatly affected if the flounder becomes blind or has a damaged eye.
A truly fun find in the seagrass beds in Bocas del Toro, Panama, was the bridled burrfish (Chilomycterus antennatus), a spiny little creature that uses its mottled yellowish-brown body dotted with numerous black spots to blend in rather than advertise its toxic, unpalatable nature. I enjoyed following this little critter as it would swim a short distance and then go lie motionless among the seagrass, acting as if it was invisible. It has the ability to become lighter or darker, depending on the situation. I do consider it a lucky find as its coloring is perfect for blending into a visually cluttered environment such as a seagrass bed; I would not have spotted it if it had not swum away when I startled it.
Where some fish hide and blend in, others actively forage, and these have to exhibit another form of camouflage to reduce their chances of becoming a predator’s next meal. A host of reef fish rely on disruptive coloration to break up their shape and form, making it difficult for a predator to spot them. Stripes and bands are the tools most commonly used to disrupt a fish’s silhouette.
This strategy is particularly effective in environments with dappled light such as coral reefs. Schooling fish like the Atlantic spadefish (Chaetodipterus faber), with distinctive disk-shaped bodies draped in bands of black, use this strategy effectively. As the fish move, the bands can appear to shift and blur. making it difficult for the predator to target a specific individual. Another important element in disruptive coloration is the addition of a facial stripe that de-emphasizes the face and hides the eyes. It is thought that masking the eye makes it difficult for a potential predator to distinguish the head from the tail. If you add a false eyespot near the tail, as in the case of the four-eye butterflyfish (Chaetodon capistratus), it becomes nearly impossible for a predator to tell which way the fish is going. By flashing its eyespot, the butterflyfish can startle a would-be predator, a distraction that can afford it precious seconds to escape. If an attack cannot be avoided it may create misdirection, resulting in an attack to the less vulnerable tail region. Eyespots are a remarkable example of mimicry and deception in the marine world.
Many open ocean fishes such as sharks and tunas tend to be two-toned in color, with a dark upper surface and a lighter underside that closely matches the tone of their surroundings. Countershading is a simple but effective form of camouflage in this watery environment. During its predatory excursions, a shark, finding itself below a sea turtle, a favorite prey item, will have a greater chance of going undetected by the turtle because the shark’s darker upper surface allows it to blend in with the dark water or dark reef below. The same situation will result in reverse: When the shark swims above the turtle, its light underbelly blends in with light colored surface water. Countershading is an important weapon for many predators to go undetected by their prey, when even a slight delay can make the difference between a successful attack or a wasted effort. Two can play this game, however, and the countershaded turtle also uses this strategy to avoid becoming shark food.
Where some camouflage, others use striking color patterns to warn others off; this is known as aposematic coloration. In most instances it serves as a warning signal to potential predators to indicate that the target fish is poisonous, venomous or just dangerous and unpleasant to eat. This usually takes the form of patches or spots of red, yellow, orange, or white. A reef resident that uses its color pattern to signal its potential for aggressiveness and to be left alone is the chain moray eel (Echidna catenata). This beautiful eel can be recognized by its yellow, interconnected chainlike markings and yellow eyes. Others use flashes of bright colors to signal their irritation as a warning, such as the flying gurnard (Dactylopterus volitans). When threatened, this unique creature spreads its wing-like pectoral fins, revealing bright markings, probably to startle predators and send a visual warning that makes it appear toxic and larger than it really is. The most iconic example of aposematism in the Caribbean is the boldly patterned invasive lionfish (Pterois volitans) with its distinctive venomous spines. There is just no mistaking that this is not a creature to be messed with.
The amount of examples we can cite is vast. What is clear is that color pattern cues serve as indispensable tools in the survival strategies of reef fish. The role of color and pattern in the lives of reef fish is truly fascinating and cannot be addressed in one article; in Part Two we will look at the role color patterns play in mate selection and social interactions.
