Chthonic Wildlife Ramblings

Many people will be familiar with the nursery-web spider. The female builds a nursery of tough silk around her egg sac, amongst some foliage. It is though a hunter rather than a web-builder and has strong limbs and a trim abdomen.

One thing though is that a lot of people have never seen the actual spider. I remember going on a Waikato University Field Trip (as a tutor) and spotted one in the foliage. I pointed it out to the staff member in charge- Keith Thompson. I mentioned that its scientific name was Dolomedes minor. This provoked the retort of "...if that's minor, I'd hate to see Dolomedes major".

A few years later my sister sent me one from her garden to identify, as she was concerned that this was an invasive species. New Zealand spiders weren't supposed to be that big. Casual identification of spiders is just one of the in-family services I provide

The best way to see these spiders is actually at night-time. Most of NZ's spiders are actually more active at night. Of course, I appreciate not everyone gets thrilled by the idea of going into dark NZ bush at night to see the spiders frolicking.

So here's some pics from one evening's expedition:

Male

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Female guarding nursery web

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Closeup of female

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In an earlier post of mine, I mentioned the problems of taking pictures of nocturnal arthropods. Last night I had another expedition into a small patch of bush.

Many NZ arthropods are nocturnal, so the best time to see them is at night-time. Now getting a great picture could be done simply by catching some of these creatures, bringing them home and then staging a 'shot'. That doesn't exactly appeal to me.

But taking a picture at night- in NZ bush- creates all sorts of problems. First up, the ground is going to be very broken so setting up a tripod is rarely feasible. Holding a camera weighted down with a decent flash and good macro-lens steady isn't all that easy.

Second, even the larger of our arthropods is still small when viewed down an SLR. And at night time, seeing the beast is next to impossible. So you've got to bring enough portable light, that you can at least see what you're focusing on. But the light conditions are still poor, so actually getting a good focus on the creature is also very hit-and-miss.

I think these 2 shots illustrate this- even if you think the animal is in focus it probably isn't. But sometimes you will get it right...even if the animal won't pose for you perfectly (sigh).

Unlike the reflex lens, the macro lens is much sooner mastered. Here's a close-up view of a beetle larva shot- the wee creature was found under a log on the margin of some native bush.



Not entirely sure of his taxonomic grouping- the antenna put me in mind of a cockchafer. There's a bigger picture in the photo-album.

High school students in the Northern Territory discover 33 new spider species

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With all the focus on saving animals like whales, kiwis and tigers, it's easy to forget an important detail. Most endangered species are invertebrates and lower plants. One might even argue, that our extremely poor knowledge of invertebrates, means that many more are endangered or threatened than we actually realise.

This state of affairs, is unfortunately promulgated throughout the policy arena. At the big SCB meetings, the numbers of vertebrate biologists greatly outnumber the invertebrate guys. There are perhaps 20 million different kinds of insect, and a couple of thousand different species of mammals. And yes, the invertebrate guys do feel a bit twisted and bitter about this .

This lack of scientific interest feeds through into recovery work. Basically, if you're an invertebrate (all other things being equal), you are not only less likely to benefit from a recovery plan, the chances that this plan will be 'underfunded' is much greater.

Invertebrates on the other hand, and much more genetically diverse than mammals. There are less genetic similarities between related species of invertebrates. This may simply reflect the taxonomic truth, that we are better at finding small signficant differences in mammals, than we are at recognising big significant morphological differences in invertebrates.

Invertebrates also do not benefit from protected areas in the same way that vertebrates do. Invertebrates can maintain populations in much small areas than mammals. You're much more likely to be living next to a threatened species of insect, than any other kind of animal. This means many populations (potentially) live outside official reserves. On the other hand, invertebrates suffer much more from 'patch separation'. It's their little legs- they find it much harder to move from one patch to another.