Thursday, 24 September 2015

Colours in Nature: orange - invertebrates

Back from another wonderful trip to South America - you'll be seeing more on that very soon - so this offering is 'live' again. Last time, in looking at some orange reptiles and frogs, I mentioned the class of chemicals known as pterins, which were first discovered as pigments in the wings of Pierid butterflies; the best-known of these are the ubiquitious Cabbage Whites, but there are many yellow, and of course orange ones too. Since then pterins have been found in the wings of many other butterflies, as well as wasps and crustaceans, but it is highly likely that they are the basis of other orange invertebrates too. But we might as well start with some orange butterflies from various places, including right here in Canberra.
Australian Painted Lady (though this one is a male Lady!) Vanessa kershawi,
on Isotoma sp., Australian National Botanic Gardens, Canberra.
And I can't really omit a butterfly with Orange in its name, though I reckon it's stretching the definition a tad - not for the first time, as observed in my previous Orange postings.
Orange Bush-brown Mycalesis terminus, Ingham, Queensland.
Both these species are in the huge and colourful family Nymphalidae; despite the history of pterins
I can't actually find a photo of mine depicting an orange Pieridae.
I can offer orange butterflies from Africa and South America too, both of which (if my identification is correct, by no means something to be assumed) are also Nymphalids.
Cymothoe sp., Bwindi Impenetrable National Park, Uganda.
This is a genus of some 70 species restricted to the great forests of West and Central Africa.
Heliconius sp., Manu National Park, Peru.
This widespread and diverse neotropical genus advertises its unpalatability - it takes up nasty cyanides
from its food plants - with bright colours. A lot of work has been done on Mullerian Mimicry in this genus,
where many species resemble each other to reinforce the message to predators. Additionally other, perfectly palatable, butterflies also mimic Heliconius for their own protection (known as Batesian Mimicry).
Two Red Flashers Panacea prola, (with a blue friend, hitherto unidentified by me), Manu National Park.
Despite the common name, these look pretty orange to me!
Orange wasps, you may recall, have also been identified as deriving their colour from pterins. Here are a couple of examples.
Spider Wasp, Family Pompilidae, Machu Picchu, Peru.
Like the butterflies, the wings are the orange aspect here; this is not always the case however.
I assume, but do not know, that the orange legs and bodies of many other wasps are also down to pterins.
'Fire Wasp' (local name, for its ferocious sting) Urabamba, Peruvian Andes.
Potter Wasp, Family Vespidae, Kata Tjuta NP, central Australia.
She needs a lot of water to construct the characteristic mud nests.
Another spider-hunter, this time near Winton, western Queensland.
As for other orange insects, I'm not aware of work that has been done to identify the relevant pigments, but it seems likely that pterins are also involved.
Patagonian Bumblebee Bombus dahlbomii Torres Del Paine National Park, Chilean Patagonia.
This magnificent insect - the world's largest bumblebee - is at risk of extinction following the deliberate
introduction of European bumblebees, carrying parasitic protozoans which are fatal to their Patagonian
relatives, though they themselves are immune.
Chrysomelid beetle munching its way through an acacia phyllode,
Whyalla Conservation Park, South Australia.
Ladybird Coccinella transversalis, Namadgi NP near Canberra.
Harlequin Bug, Family Scutelleridae, Undara National Park, Queensland.
And lastly, moving away from the bush to the sea, pterins have been identified in orange crustaceans, presumably including this lovely crab.
Male Orange-clawed Fiddler Crab Uca coarctata, Mission Beach, Queensland.
The ludicrously enlarged claw is useless for foraging - the other, small claw does all the food gathering - and is solely
used for signalling superiority, and fighting when bluff fails.
So, that will about do us for our excursion into the orange world. Except that I should come back one day to celebrate some orange flowers - but perhaps not just yet.


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