Here is a selection of fascinating photos taken while on a routine nursery web survey. Whilst not a formal behavioural study in the sense of the others written up here, it is worth including here as the most appropriate section overall.
I can’t take credit for the interpretation of the pics and videos -I sent them to Dr Helen Smith who kindly interpreted them for me. These are mostly her words:
Though this individual is not behaving in any particular way, we were interested to know more about the brightness of its bands which we found striking. He appears to have lost his second left leg. There is also a recorded conversation about its age in a courtship video below -Helen comments on this too.
“Band colour and brightness varies between individuals and is not particularly age-related. The exceptions to this are (1) that tiny juveniles tend to have lighter ground colours and (2) adult females tend to have more subdued band colours, although you do see some brightly banded ones. I’d be interested in trying to quantify the latter!”
“Re the overheard conversation backing this video, this year’s juveniles will only be a max of 3 weeks old and a very few mm long – you’re unlikely even to notice them and they’ll mainly be in the marginal vegetation rather than on the water. Anything vaguely ‘middle sized at the moment will be from last year’s broods.”
“This couple are indeed a courting pair – the female is already quite gravid. The bobbing in the video is part and parcel of the courtship communication – both sexes do it. In the male it only signals intention but in the female, done (I guess) at a particular frequency or intensity. it can also signal lack of interest! Subtle stuff.”
Here is a nursery web (top right) and below and to the left is a spider. Try and spot it. If you can’t the answer is at the end of this post.
Here he is -and it’s a male. He has a slim abdomen and clubbed palps like boxing gloves -these contain sperm, ready to inseminate the female, facing him. You can see her legs between the two sedge leaves forming a triangle.
About the above videos (of the same pair of spiders as in the stills), Helen says: “This shows another courtship sequence with the male doing the classic leg-tapping to create concentric waves that signal intention to the female. This can be a very protracted business and the fact that she moved away doesn’t necessarily mean that she’s not interested and won’t accept him in the end.” Apologies for the extra noise -no one was aware I was recording!
This shot shows a female guarding her nursery. Her body is quite thin because she’s hardly eaten for weeks while carrying her egg sac but her palps are straight and not clubbed as a male’s would be.
Here the same female is being defensive and guarding her nursery. You can see one of her palps very clearly – and it’s straight, not clubbed at the end. Apologies for the focus -not a lot of control with the apparatus -my camera battery had run out and I used a camera phone held only about 18 inches away, so she had detected my presence. She is holding her right first two legs in a V-sign -very appropriate!
Answer to the spotting question: He’s at the bottom of the photo, to the right of the triangle formed by the two most right hand sedge leaves. In the apex of that triangle you can partly see a female facing him.