word worm is derived from the Latin word Vermes which used to describe any
kind of worm-like animal. Worms are different things to different people.
To a gardener a worm is an earthworm, to a nurse a worm is a tapeworm or
roundworm, and to a diver a worm is a tube-dwelling polychaete.
Generalizations, then, just do not work with regard to worms. So, what is
Worms fall into four non-related
distinct groups or phyla. The simplest are the flatworms, best known for
their parasitic members the tapeworm and liver fluke. Also pararasitic are
the round worms or Nematodes, well known to dog owners as parasites of the
The third group is of minor
interest and comprises the ribbon worms or Nemertines. These unsegmented
ribbon-like worms vary from a fraction of an inch up to 20 feet in length.
They have a unique method of feeding; they can shoot out a proboscis armed
with a sharp spike or stylet from a muscular sheath at the front end of
the body to trap their prey. They can vary in colour from black to white
through almost every colour. Unfortunately, these fascinating marine worms
tend to be nocturnal and fairly uncommon. I have only seen two in many
years of diving in Nassau.
Of interest to every diver, especially
those specialising in phototography, are the true worms or Annelids. The
three groups or classes of true worm are the earthworms and their kin, the
leeches, and lastly the Polychaetes or Bristle worms, the true marine
For convenience, Polychaetes are
divided into two loose groups — those that live freely and three that
live in some sort of tube. We have comparatively few free-living worms in
the seas of the Bahamas. We do not see the large Nereis -
the common textbook example of a Polychaete, known in the States as
a Clamworm and in Britain as a rag worm. Nor do we see Aphrodite -
a short fat furry worm resembling, in size and shape, a mouse —
hence its name, the Sea Mouse. We do have, however, two or three other
species of bristle worm that may be seen roaming freely across the reef or
sand. They owe their relative freedom to the multitude of delicate
bristles that cover them. If they are picked up the bristles break off in
the skin and cause extreme irritation.
tubeworms are among the most beautiful of marine animals. Resembling
flowers, they have been thought in the past by many to be plants. The
petal-like tentacles are, in fact, a combination of respiratory and
feeding mechanism, for they take both oxygen and food particles out of the
surrounding water. The tiny food particles are passed in a never-ending
mucus band back to the mouth where the whole thing, mucus and food, is
taken in together. Along the tentacles are light sensors that can detect
shadows and signal the worm to pull its gills into the tube with
remarkable speed when danger threatens.
The beautiful spiral Christmas
tree worms that grow out of coral heads have another means of defence, for
hidden under the extended gills and arching out over the entrance to the
tube is an extremely sharp limestone spike, so that if a worm swim to the
surface predator were to lunge at the extended worm it might find an unpleasant
surprise In wait.
The tube itself is usually made out
of a cement secreted by glands behind the mouth. It may be reinforced by
sand grains and mud particles or pieces of broken shell. The tubes of most
polychaete worms are concealed, but those of the honeycomb worm (Sabellaria)
grow in such masses that the reefs formed may be a danger to shipping.
Annelid worms all have interesting
mating habits. Even the humble earthworm is hermaphrodite (male and
female) and goes through an amazing process to ensure that both worms o a
ir are fertilized. The Palolo worm loses its rear end once a year on one
particular night during the last quarter of the moon in June and July.
Millions of these pieces of worm swim to the surface to release
their eggs and sperms while the front halves of the worms go about their
normal business on the seabed. The larva remain planktonic and can be
carried great distances by the tides before a fraction of one per cent
eventually settle and metamorphose into worms, to renew the cycle once
tubeworms show some remarkable adaptations to their habitats. One, the
Medusa worm (Loimia Medusa), has a crown of whitish tentacles which
display the most amazing muscular powers, The two-inch worm, like most
polychaetes, remains in its tube under a rock or ledge, but extends its
tentacles out for maybe as much as four feet to seek for food particles
and draw them back to its mouth. The feat is amazing when one considers
that the tentacles are more than a thousand times longer than they are
thick! This lowly worm has achieved a mechanical skill that man may never
match, despite the complexity of his machines.
Worms, along with the individuals
belonging to other invertebrate groups, are countless by human standards;
they are all around us in the ground, in the sea, in our domestic animals,
and sometimes in our pets and even us. Most worms are ignored and unseen,
and in most cases never threatened by man.
If only this were true for higher
forms of life. For them – as for so many species of amphibian, reptile,
bird, and mammal, life is a struggle that can only end in oblivion.
Those of us that are concerned with
man’s impact upon his environment may never be able to avert the day
when extinction comes to another species, but we can certainly slow it
Meanwhile, worms will still be with