The greatest feeling in biology is undoubtedly that which comes with seeing a particular organism for the first time. You can read on it, study specimens of it, think you know it inside out - and then you actually see one, and suddenly you realise that it's so much more than you ever imagined. This is the feeling that drives bird enthusiasts to spend their life's savings on trips to some malaria-infested corner of the third world to try and catch a brief glimpse of the Lesser Spotted Turntwick or some such. This is the feeling that inspires deep-sea biologists spending whole days lying on the bottom of the ocean in miniature submarines in which they can't move more than a few centimetres in any direction, just so that they can watch a tube-worm wave its tentacles at them. It can only be described as a mystical experience, this moment in time that really brings it home to you that this is why you study biology.
I had a brief such moment yesterday, when I encountered representatives of an animal phylum that I'd never seen before. I was tutoring a lab for which some live specimens of encrusting bryozoans had been brought in. Unfortunately, the bryozoans were being very unco-operative and refusing to emerge from their protective skeleton. While scanning the colony under a microscope to try and find some emerging zooids, I saw some soft white structures overgrowing the colony. A quick change of focus brought them into view, and I was presented with my first ever view of an entoproct.
It seems to be quite impossible to find an image available online that does these animals justice. The one at the top of the page comes from here, while the picture above from here shows part of an entoproct colony on the left (the other two animals are a gnathostomulid and a myxosporidian). Entoprocts are minute colonial animals with a body shaped like a wine-glass, topped by a ring of feeding tentacles. The relationships of entoprocts are rather uncertain at the present point in time. In the past they were included in the Bryozoa, but it is now widely agreed that the apparent similarities to Bryozoa in the stricter sense are only superficial, and the two groups are probably not closely related. It is accepted that entoprocts belong somewhere within the Spiralia, the large group of animals that includes, among others, molluscs, annelids and flatworms (and probably bryozoans), but exactly where in this group they sit is very much an open question. The specimens I saw each arose from the substrate on their own individual stalks, which according to the guide book on Australian marine life that was lying in the lab meant that they belonged to the family Loxosomatidae, as opposed to the Pedicellinidae which have multiple zooids budding from a single stalk.
Personally, though, I was stunned by just how beautiful these little animals were. They looked like minute, frilly tulips, balanced ethereally on their long slender stalks. If I looked closely, I could see a line of fine white filigree connecting each individual to its neighbours in the colony, forming delicate tracings over the substrate. I was enthralled, and the thought crossed my mind - "This is why I study biology".