EPOW - Ecology Picture of the Week

The Surprising Array of "Cleaner Species"

"Cleaner Species" Functional Group
Galapagos Islands, Ecuador

Explanation:  This week we are exploring a little-studied "functional group" of species of the Galapagos Islands of Ecuador.  

This is a very disparate group of species that share a common ecological function of acting as "cleaners" of larger-bodied species, by picking off ectoparasites and other small organisms.  

A "cleaner" function is well known in marine coral reef waters, with fish such as with the bluestreak cleaner wrasse (Labroides dimidiatus), and with many species of cleaner shrimp.  

But it was most surprising to find this set of terrestrial species on the Galapagos Islands also serving this cleaner function. 

The group is represented in the main photo block, above, and itself consists of some very surprising species:  Yellow Warblers, which are usually insectivorous birds of riparian areas elsewhere; Lava Lizards, which themselves constitute a set of 7 species evolved on various islands of the Galapagos Archipelago; Galapagos Mockingbird, an omnivorous descendent of an aboriginal mockingbird species that initially colonized the islands and evolved independently; Sally Lightfoot Crabs that usually just pick algae off intertidal rocks along the shoreline; and even at least one of the famous Galapagos finches, the Small Ground Finch, which is usually a seed-eater!  

So who do these "cleaner species" clean?  

Here is the set of larger-bodied host species I observed being "serviced" by this cleaner functional group:

And this too is a surprisingly diverse array of cleaner host species, including marine and land iguanas, sea lions and fur seals, and even the iconic giant tortoises!  

And, finally, here are a few examples of the cleaner species in action, scrambling over the bodies of some of these host species in search of mites, parasites, and other prey:

The advantages to both cleaners and "cleanees" are obvious -- the former get a snack, and the latter get relieved of their parasitic burden.  And the host species likely do not "cheat" and try to consume their tiny cleaner friends, just as sharks have evolved to tolerate cleaner fish that provide a similar function and do not consume their cleaner friends.  

So I found it fascinating to have found the development of this clearer functional group on the Galapagos Islands to essentially match the same functional roles that have evolved in marine environments.  

These islands that inspired Charles Darwin still seem to provide endless surprises!