By some estimates there are more species of "worms" than insects! Most of the large groups, the phyla of Roundworms (Nematoda), Flatworms (Platyhelminthes) and Segmented Worms (Annelida) are barely known to most of us. The very common and important other "wormy" groups are virtually unknown. We use these organisms consciously as food, to help keep our substrates from compacting and channeling, as filter-feeding "cleaners" in marine reef systems and dook it out with them as disease carrying and causing parasites and competitors.

Why the lack of respect? What is this, another example of species-centricity? Worms are everywhere; in your hair, in the air, in the deepest seas, warmest waters, driest deserts... Doing everything: parasitic, free-living, filter-feeding planktivores, detritivores, ferocious predators, sneaky vacuum cleaners...

Yes, worms are wormy; often slimy, reclusive, mysteriously appearing and disappearing. But they were here first! All major and minor worm groups were on the planet in full force before the Cambrian. They are still critically functioning as aerators, facilitators of decomposition and general energy transfer/recycling and as store houses of food energy and webbing themselves. Let's use this brief article to discuss one phylum of worms often encountered on purpose and accident by marine hobbyists, Polychaete Annelidans:

Classification: 

In the world of zoological taxonomy feather dusters, duster-cluster, bristle, fire, fan, tube...worms are grouped/placed in the Annelida, generally known as the "segmented worms", in reference to their metamerism or segmented appearance.

This segmentation allows for different types of locomotion, several environments. External and internal segmentation is obvious in the body, parapodia (lateral processes), nervous, muscular, excretory and circulatory systems arranged in repetitive placement.

There are three living Classes:

1) Oligochaeta, meaning "few bristles", the ubiquitous "earthworms" that indeed do have small body bristles.

2) Hirudinea, the leeches. All basically parasitic.

The above two are mostly freshwater and terrestrial and differ generally in basic ways in terms of internal anatomy, having permanent gonads...unlike the

3) Polychaeta ("many bristles"), some are downright prickly, are mainly marine. They have a head end (prostomium) with a typical sensory array of tentacles, papillae, eyes... and a posterior segment (pygidium). New sections are added right before the pygidium. What else? longitudinal muscled bands effect motion through contracting against a fluid filled body cavity (coelom). The digestive tract is a more or less straight tube running from the anterior mouth to the posterior anus. Most do have a "closed" circulatory system, blood and a "heart", an anterior dorsal ganglionic mass (brain), lateral nerves in each segment, blah, blah, blah. And they're neat! Some are big (larger than your hand, longer than your fish. And here, fellow pet-fish commandos, I must confess to a certain period of intransigency when even I lived on the public largesse. For a couple of years in grad. school I did "environmental" work sorting and identifying benthic marine invertebrates, principally polychaete worms. My dear cubicle mate actually had a beautiful graphic of a Glycerid polychaete worm with double everted jaws (shades of Aliens I and II & III), multiple eyes and specialized parapodia with a blasphemous label "God is a Polychaete!

There are so many species of polychaetes occurring most everywhere in marine environments with known life "habits" that much can be discerned by collecting, i.d.ing, counting 'em up and measuring now and later to determine "impact" of human or other activity.

So yes, money can be made with life science degrees! My roomie used to do Errantiates and I'd get stuck with the Sedentariates. Hey, what are they!? Glad you asked; back to the story at hand:

Polychaetous Annelids are sub-divided into two sub-classes:

Errantiate Polychaetes (Bristle, Fire...) Worms... On Parade!

Bigger PIX: The images in this table are linked to large (desktop size) copies. Click on "framed" images to go to the larger size.

To: Featherduster, Sedentariate Polychaete Worms