Live Sand Examination

[ATJ]

I just want to clarify that I am doing the observations and calculations correctly.

At 20X magnification on my stereo microscope, the field of view is 11mm in diameter and so covers an area of 0.95cm<SUP>2</SUP>. Now, if I see more than one animal in the field of view (on average), I'm doing better than 10,000 animals.m<SUP>-2</SUP>, aren't I? That's good right?

So far I have seen quite a few nematodes and ciliated protozoans, with a few crustaceans, mainly copepods.

Now, I did find this interesting crustacean. It is about 5mm long and living in a cylindrical tube. Normally, all that produces is its triangular shaped head with noticible eyes and a two pairs of segmented antennae. Hairs are noticible on the both antennae and they are at 1, 3, 9 and 11 O'clock. When it comes further out of the tube, I can see multiple segments behind the head each with a pair of appendages. It looks a bit like the cephalocaridan pictured in R&B (Figure 14-10 A) other than the shape of the head.

 

[ATJ]

Here are some pictures of the crustacean:

I also spotted a really nice polychaete. It was amlost clear, but had a black shape just behind the head.

 

[rshimek]

Hi Andrew,

It sounds like your sand examination was done correctly.

You might want to save the crustacean in some rubbing alcohol until we get to them, and then return to it for closer examination. The pictures didn't come through at my end. You might want to email them to me.

Cephalocarids are planktonic and so won't be in tubes.

In some of the polychaetes, the gut in the region just behind the head, is muscularly thickened and functions like a gizzard. It appears dark or black with transmitted light illumination because it is so dense.

[ December 27, 2001: Message edited by: rshimek ]</p>