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Catalina Island Leadership Program

Phoenix Country Day School

Kelp Forest Information Links

Channel Islands National Marine Sanctuaries

Introduction: For 14 years, the Phoenix Country Day School 8th grade class has traveled on a science trip to Catalina for one week in the fall. Catalina is one of the Channel Islands, 26 miles off the coast of California. Our research topic was: “How do the Shovelnose Guitarfish and the Cabezon disguise themselves; and does depth make any difference in their camouflage technique?” In order to research this, we would need to take depth measurements at Howland’s Landing Cove and observe the fish at depth. We also researched background information on the web and in books.

Research: Camouflage is very important to some creatures. It is important because camouflage protects prey and gives advantages to ambush predators, like the frogfish. Frogfish disguise themselves as sponges when they are young and as coral when they are older. There are several types of camouflage. There is color camouflage, scent camouflage and body shape camouflage.

Color camouflage is where fish change color in order to blend in with their surroundings or disguise themselves as something uninteresting or dangerous to predators. Some skin cells, called chromatophores, contain colors, or pigments, that can change the fish's color quickly. The flounder is an interesting example of this. One scientist put a flounder against a checkerboard to see what would happen. In less than a minute, the flounder's body started to resemble the black and white squares of the board.

There are also counter-shading and deceptive marking techniques. Counter-shading is a technique that fish use where the parts of their body that are normally in shadow become lighter and the area of their body that is usually light is darker. This minimizes shadow and reflection, making the fish nearly invisible to predators or prey from above and below. A good example of deceptive markings is the butterfly fish. They have large eyespots on their tails. This confuses predators and causes them to attack the tail of the fish instead of the head.

Some fish also use scent camouflage to prevent their smell from being detected by predators that rely on smell. For example, the Queen Parrot fish surround themselves with a bubble of mucus when they sleep to protect themselves from moray eels. Body shape camouflage is where the shape of the fish naturally blends in with a certain environment. For instance, octopi are capable of changing their body shape to resemble a pile of rocks, a sandy hill or whatever shape is required to blend into the background.

While conducting our background research, we found many interesting facts about the Shovelnose Guitarfish and the Cabezon. In Spanish, Cabezon means stubborn or big headed. They have a large head, spinal dorsal fins all the way down their back, and their body slowly tapers to a thin point before the large tail. Found from the Baja Peninsula in Mexico to Sitka, Alaska, Cabezon grow up to 30 inches and live in shallow, rocky areas. They mate at the same site every year and defend their eggs aggressively. Cabezon eggs are poisonous, making any egg stealing fish and humans ill. The Cabezon is nocturnal and camouflage themselves by using their ability to change color. Their camouflage color is usually mottled brown in order to blend in with their rocky habitat.
Shovelnose Guitarfish can grow up to 5.5 feet long. They are flat, sandy brown, have two dorsal fins on their backs and actually look like guitars. Crabs, worms, clams and other fish form their diet. Their habitat is the ocean’s sandy bottoms. Shovelnose Guitarfish are diurnal and are also well disguised. In comparison to the Cabezon, the Shovelnose Guitarfish doesn’t really use color camouflage. They dig themselves into the sand to hide. Their natural color and their flat body shape allow them to blend in with ease.

Our base was the Catalina Environmental Leadership Program or CELP. We kayaked in Howland’s Landing Cove to collect our research data. In order to take depth measurements, we used a lead weight tool. This was a lead weight attached to a string. Each red mark on the string equaled one meter, easily allowing us to measure the depth. The depth range was between 7 to over 18 meters. We also used a GPS to track where we took our six depth measurements.
While we were in Catalina we went on four snorkels in the cove, three of which were during the day, and one at night. The first snorkel was mainly to orient us with the snorkel gear and snorkeling techniques. The remaining three snorkels were used to observe the fish that we were researching. We looked for the Shovelnose Guitarfish during the day and the Cabezon during the night.

We found that Shovelnose Guitarfish normally rest on the bottom of the cove. Because they blend in perfectly with the sandy bottom, it is difficult to see them at first. After we knew what to look for, we found that they were usually spread across the bottom at depths of around 18 meters or deeper and in groups of two or three. We saw one or two groups on each snorkel. Most of the Guitarfish were larger full-grown adults, but we saw several smaller juveniles too. When our dive instructor disturbed one, we learned that they propel themselves with their tails and can move very fast.
Unfortunately, we didn’t see any Cabezons on the night snorkel, but our teacher, Mrs. Youngman, did see one. She said that it was swimming along the bottom, well camouflaged with the sand, heading for a pile of rocks. Because Cabezon are very good at camouflage, it is not surprising that we did not see any of these fish.

Conclusion: The second part of our research question was whether or not the depth makes any difference in the camouflage technique of the Cabezon and the Shovelnose Guitarfish. In our observations, we found that the depth only makes a difference in the appearance of the camouflage, not the technique used by the fish. The deeper the depth, the more effective their camouflage or hiding technique becomes. The fish don’t change their camouflage technique with depth.
Earlier this year we learned about turbidity. Weather can affect the clearness of the water. When it rains, sediment is washed into the ocean, making the water cloudy. Luckily, we did not encounter any rain, making the water surprisingly clear throughout the trip. However, we found that camouflage is more effective at depth because of the filtering out of light and increasing turbidity.