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, considered here, the latter including the possibility of UV protection. 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. CLICK ON a topic to learn about it.
 
 
 

Function of colours: defense: warning of toxicity

 
 

We know from other parts of the VIRTUAL DIVE that camouflaging 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 large topic is divided into a section on snails, considered here, and sections on SEA ANEMONES JELLYFISHES & HYDROIDS, ZOANTHIDS, and FISHES presented elsewhere.

NOTE see DEFENSES: INVERTEBRATES: BEHAVIOUR: HIDE AWAY/CAMOUFLAGE

 
 

Snails

 
 
seahorse dive leader for Biology of Caribbean Coral Reefs website photograph of gorgonian with flamingo shell and basket star

"Well, who's this on the gorgonian? It's a good example of different types of defense...bright warning coloration of a toxic flamingo-tongue shell, and a camouflaged non-toxic basket star, waiting for night to come out to feed." - Cuba 2007

NOTE Cyphoma gibbosum

NOTE unknown ID

 

 
 

photograph of flamingo-tongue shell on a gorgonian
Flamingo-tongue shells
eat the flesh of gorgonians and are themselves thought to have toxic flesh. Their brightly coloured mantle tissues extend up on both sides of the shell and are thought to warn off attacks from predatory fishes.

NOTE more information on flamingo-tongue shells and their toxic flesh can be found at DEFENSES: INVERTEBRATES: TOXIC CHEMICALS: TOXIC/NOXIOUS TISSUES OR SECRETIONS: SNAILS CRABS CEPHALOPODS & SEA CUCUMBERS

 

 

Flamingo-tongue shell Cyphoma gibbosum on
a warty sea-rod gorgonian Eunicia sp. 1.5X

  An example of warning coloration in snails that relates to prey sea anemones and hydroids is the bright demarcation of the tips of the dorsal cerata of certain nudibranch molluscs. These shell-less snails eat hydroids and anemones, pass the stinging cells (nematocysts) through their digestive tracts undischarged, and house them in perfect working order in special sacs at the tips of their cerata. Photograph courtesy Anne Dupont, FL.
 
schematic showing nematocysts housed in sacs in the ceras of a nudibranch Dondice occidentalis, courtesy Anne Dupont, Florida

The nematocysts are positioned in a sac with their discharge ends facing outwards. When irritated, the nudibranch squeezes the nematocysts from the sac and out an opening in the ceras tip, at which time they discharge and may sting whomever is doing the irritating. The mechanism by which nematocysts are eaten, transported, and housed without discharging is not known.

The conspicuous white tips of the cerata are thought to be warning coloration to advertise their toxicity.

 
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