Coloration of reef organisms
 
column spacer Coloration of reef organisms
  hot buttons for colours section of Biology of Caribbean Coral Reefs website
This section deals with the function of colours. Topics of HOW COLOURS ARE CREATED and HOW COLOURS ARE PERCEIVED can be accessed via the icons.
 
 

Function of colours

  Functions of colours and colour patterns in reef animals fall into 2 broad categories of SOCIAL and DEFENSE, one topic of the latter, camouflage, being considered here. Most or all of these topics have been mentioned elsewhere in the BCCR but, by its nature, this section on FUNCTION OF COLOURS pulls them together as a broad summary. A third category of UV PROTECTION is also included in its own, short section. CLICK ON a topic to learn about it.
 
 
 

Function of colours: defense: camouflage: invertebrates

 
 

We know from other parts of the VIRTUAL DIVE that camouflaginig in reef organisms can involve combinations of colour, form, and behaviour. What follows in this section are some examples where colour and colour-patterns predominate. This section is divided into invertebrates, considered here, and VERTEBRATES, dealt with in another section.

NOTE see DEFENSES OF INVERTEBRATES: BEHAVIORAL: CAMOUFLAGE and DEFENSES OF FISHES: AVOID DETECTION: CAMOUFLAGE

 

drawing of normal red shrimpsdrawing of red shrimps at depth
Shallow-water shrimps tend to be pinkish in colour, while deep-water shrimps tend to be red. The functional advantage of this is not really known but, because of differential attenuation of light as it penetrates the ocean, colours at the red end of the spectrum, including orange, will appear black at even fairly shallow depths. The red coloration of deep-water shrimps will cause them to appear black; hence, aid in camouflaging. Drawings adapted from Hardy 1958 The Open Sea Collins, London.

 

Deep-water Mediterranean shrimps Aristeus antennatus
as they would be seen in a bucket at the surface at
daytime after being collected in a plankton-net tow

 

The same shrimps seen at the depths
they normally live during daytime

  Well, this sounds plausible, but why has there been no selection for naturally black deep-water shrimps? It's not that they lack the ability to manufacture black (melanin) pigments, as many species are known to have black chromatophores (melanophores). In fact, the red carotenoid pigments involved are not required to be manufactured, as they are derived from the shrimps' algal foods, so the process of being red presumably requires less energy than a process of being black.
 
 

photograph of red-banded lobster Justitia longimanus
Red-banded lobsters generally hide away in crevices during the day and forage for crustaceans, snails, and other shellfishes at night. Once again, we presume that the red coloration is for camouflaging. But, what is the function of the color pattern? Well, at even reasonable depths in daytime, in the absence of red wavelengths, the pattern would be black and white stripes, potentially a good pattern-disrupting camouflage. Alternatively, or as well, a black and white pattern could be for intraspecific recognition, such as sexual.

 

 

 

Red-banded lobster Justitia longimanus
photographed at night 0.25X

 
 
Let's review this with the lobster for clarification:  
cartoon 1 of a series of 6 of a diver interviewing a lobster about its coloration cartoon 2 of a series of 6 of a diver interviewing a lobster about its coloration
cartoon 3 of a series of 6 of a diver interviewing a lobster about its coloration cartoon 4 of a series of 6 of a diver interviewing a lobster about its coloration
cartoon 5 of a series of 6 of a diver interviewing a lobster about its coloration cartoon 6 of a series of 6 of a diver interviewing a lobster about its coloration
 
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