When we think of camouflage in nature, we often only consider the colors that animals use to blend in with their environment and hide from predators. What many people don’t realize is that in marine species there are multiple forms of camouflage:
- Chromatophores and Mimicry
- Morphological Changes
Each form of camouflage is crucial to the survival and overall fitness of these animals. Not only does camouflage protect individuals from predators, but it also disguises them from prey enhancing their foraging success.
Chromatophores & Mimicry
The classic form of camouflage we are familiar with is changing colors to mimic an animal’s surroundings. Marine animals use chromatophores in their skin to rapidly change color. Chromatophores are a type of cell found in the skin that contains a pigment to provide color. The amount of time it takes for the animal to change color is determined by the abundance and dispersion of chromatophore cells they possess.
There are two methods by which the cells may change color, a primary response to light or a secondary response via an animal’s visual system.
Flatfish and cephalopods, such as squids, octopi, and cuttlefish, are the common marine animals that use this form of camouflage. They change their pigments to match that of their surroundings through their visual system pathways. The patterns, colors and brightness they develop stem from the contrast, size, and existence of visual edges of the specific objects. Since they use vision to change their pigments, obstructions to their eyesight can affect their ability to properly camouflage.
Countershading is a form of camouflage that does not involve any morphological or physical changes of the animal. Various marine organisms are two-toned, meaning their dorsal (top) side is dark in color and their ventral (bottom) side is light in color. Countershading is an adaptation developed by prey and predators to enhance their overall fitness.
If you go to the aquarium you may notice that top predators, such as sharks, exhibit countershading. Sharks, whales, and dolphins use countershading as a form of camouflage in order to sneak up on prey. Their dark top allows for them to go unnoticed by prey swimming closer to the surface. Their color blends into the dark shadows of the deep ocean. However, their light underside also enables them to be hidden from their prey below them. When looking up to the surface their light bodies blend in with the exposed sunlight.
Fishes, turtles, penguins, seals, and other marine prey species can all exhibit countershading as well. In this case, countershading is an adaptation used to protect themselves from predators. Just like for predators, when looked up upon their light undertone allows them to blend into the surface light. Their dark dorsal side allows them to deep dive for food while still blending into the shadows of the ocean when predators look down.
The last form of camouflage used is the evolution of an animal’s morphology to perfectly blend into their surrounds. The prime example of this evolution is the leafy sea-dragon. The leafy sea-dragon is a relative of the seahorse with special adaptations to their environment. Their appendages are specially designed to appear like leaves of the kelp they live in. Their color and leaf-like appearance allows them to be almost undetectable by prey and predators. The leafy sea-dragon has used this form of camouflage to thrive in its habitat and have a stable population.
Although they are currently labeled as a least concern species according to the IUCN, this is only possible through the abundance of their kelp habitat. With the increasing rate of marine habitat destruction worldwide the leafy sea-dragon may encounter difficulties in the future. If their habitat is destroyed, the fragile sea-dragon population can decline rapidly. Since their only form of protection is this morphological adaptation to appear like leaves, once exposed they may be a target prey species for other marine animals. There are other marine organisms that have also developed morphological changes to camouflage with their environment. Preventing marine habitat destruction world-wide is crucial to maintaining the populations of organisms who have developed this form of camouflage.
Featured Image: Katie Lee Osborne/Wikimedia Commons (CC BY-SA 4.0)
“Countershading.” Surviving in the Harsh Midnight Zone | Science and the Sea, www.scienceandthesea.org/program/201107/countershading. Accessed 4 May 2018.
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