Welcome to my blog

This is where I post various musings about wildlife and ecology, observations of interesting species (often invertebrates)
and bits of research that grab my attention. As well as blogging, I undertake professional ecological & wildlife surveys
covering invertebrates, plants, birds, reptiles, amphibians and some mammals, plus habitat assessment and management
. I don't work on planning applications/for developers. The pages on the right will tell you more about my work,
main interests and key projects, and you can follow my academic work here.

Thursday 13 September 2012

Eyes in the back of my... back...

Mimicry using eyespots is widespread in nature - they are found in fish (such as the four-eyed butterflyfish Chaetodon capistratus which has them on the tail, so predators attack a non-lethal area or miss entirely), mammals (not only the 'obvious' ones such as leopards, but also the serval Leptailurus serval which has them on the backs of its ears for signalling to kittens while hunting), reptiles, birds and insects. Within the insects, butterflies and moths are probably best-known - many adult butterflies and moths have eyespots on the wings (the result of concentric pigment location around morphogenetic focus points), while the larva of the elephant hawkmoth Deilephila elpenor is famous for its conspicuous eye-like spots towards the head which are used to startle predators such as birds.

Elephant hawkmoth larva Deilephila elpenor showing eyespots
However, there are other invertebrates that show evidence of eyespots. I've previously written about bug (Hemiptera) nymphs possibly mimicing harvestmen, and today I noticed another - the common European garden spider Araneus diadematus. This is a very familiar species, often found on its orb-shaped web in gardens, and known for the pale cross-shaped marking (made from guanine which is a by-product of its protein metabolism) on the normally yellowish, orange or brown background of the top of the bulbous abdomen in females. Other common names include 'cross spider' and 'cross orbweaver', and males are smaller and less striking, though the markings are broadly similar.

Female Araneus diadematus showing the typical abdominal colour and cross-shaped marking

Male Araneus diadematus
So far, so good - but what about the eyespots I've mentioned. Well, the spiders are generally found either in the middle of their webs as shown above or tucked away in refuges at the ends of suspension silk lines. On webs they are typically head down and seen side on, either dorsally or ventrally. However, if you look stright down from the rear, a different pattern can be seen.

Female Araneus diadematus showing abdominal eyespots
To me, this is clear eyespot mimicry and makes adaptive sense - usually being head down, the rear of the abdomen is the part most likely to be presented to potential predators, namely birds, and therefore where eyespots that could startle them would be most useful. What I find more surprising is that I've never noticed this before despite having seen many specimens; more so that I can't find any other reports which suggests no-one else has either (or at least they written about it on the 'net). As ever, comments welcome!


  1. YAY Spiders! I get lots of the Araneus diadematus in my garden. I was going to photograph a lot of them in the garden this morning, all frost and sparkly, but my camera decided otherwise. Note, to self:- Charge the battery in your camera.

    Fantastic Photos Dave!

  2. Thanks :) Frost already - where are you?

  3. reading this has given me one of those 'WOW' moments! Excellent observation.