Got the Invert Blues…

Blue is a surprisingly common colour in many invertebrate groups, especially as a tint or reflective colour on key body parts. Here we have a range of distantly related organisms that use blue pigments - or, most of them - structural characteristics of the cuticle or setae/scales (modified hairs) to give blue-tinted reflections.

You’ll may already know the Acanthanura springtail (second from top), one of my favourite Collembola: surely everyone’s favourite! This beast has a beautifully bluish pigmented body that becomes paler on preservation. Pigments often do this - they are unstable and decay, sometimes rapidly often leaving dull specimens of once vivid creatures. The others species all exhibit structural colours where the arrangement of their cuticle ‘think invert skin’, or scales, reflect light to show colour rather than containing pigment. Structural colours can last, potentially, millions of years.

These other five are, from top down:

1-  a huntsman spider (Sparassidae: Neosparassus) with blue reflections on its chelicarae;

3 - a Rhytidoponera ant, perhaps R. metallica or at least that group;

4 - a red and black spider (Nicodamidae) with blue reflections on its abdomen;

5 - a native, litter-dwelling, silverfish (Thysanura) with structurally reflective scales coating its lithe body; and…

6 - a brilliant little Marataus jumping spider (Salticidae), likewise, with stunning reflective scale patterns on the abdomen.

For organisms with structural colours, like most of these, the nature and direction of the light will have some influence on the colour of the reflection.

All from a within a couple of hours drive of Melbourne, Victoria, Australia.

Even invertebrates get the blues…sometimes.

Anatis rathvoni “Rathvon’s Giant Lady Beetle” Coccinellidae

Great Burn, Lolo National Forest, MT
July 10, 2015
Robert Niese

These massive (10mm) ladybugs are endemic to the PNW and are normally found in pines and other conifers where they voraciously consume aphids, caterpillars, and other small, fleshy-bodied herbivores. Their elytra vary in color from yellow, pale brown, to brown-red, darkening with age. Rathvon’s Giant Ladybird Beetles are named for a relatively obscure 19th century entomologist, S. S. Rathvon from Pennsylvania, who was one of North America’s first entomologists dedicated to educating the public about their local beneficial and pest-insects. Learn more about his life here.