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The Sea Shells of the Bahamas
The phylum
Mollusca (Mollusks in the USA) have been around for some 500
million years. In that time they have diversified to all habitats
and range in size from the tiniest snail to the giant squids of the
deepest oceans. They are have been used by mankind as food, for
decoration and adornment, to make trumpets and for much more. The
molluscs with snail-like shells belong to a group called the
gastropoda, the largest of which is the Florida Horse Conch - seldom
seen in the central or southern Bahamas.
There are however, some very large species
in the shallow waters of the Bahamas, that may be seen by the tourist,
the snorkeller and the diver.
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The Triton's Trumpet is one
of largest, growing to some 18 inches (45 cms) in length. In
parts of the Pacific they are actually used as trumpets, the
shell producing a fine resonance and a very loud note when
blown through from a hole made at the tip. |
Triton's Trumpet is found in crevices on coral
reefs or on adjacent sea grass beds where it may be searching for
its prey the Starfish.
| The Flame Helmet, Cassis
flammea is the
smallest of the Bahamian species of Cassis or Helmet shell.
The closely related 'Cameo shell' of the Indo-Pacific has been
historically, and still is used to carve cameos for brooches.
Cameos can however be carved from any of these shells. |
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The largest species of Helmet shell in the
islands are the King Helmet, Cassis tuberosa and
the Emperor or 'Queen' Helmet, Cassis madagascariensis.
The former has a triangular shell base, and the latter a more
rounded appearance - see below.
These molluscs have an interesting way of
feeding on sea urchins. They slowly creeps up to their prey, raise
the heavy shell high, then quickly drop the shell so that the
urchin is completely covered. Sea Urchin spines contain a poison, so
the helmet snail releases a paralytic enzyme from its salivary
gland, then it secretes sulphuric acid which dissolves the sea
urchin shell in about 10 minutes after which it can then eat the
contents of the Urchin.
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King Helmet - largest of
the Helmets and easily identified when mature by its
triangular base |
Emperor (Queen) Helmet |
By far the commonest and most well known of
the large Bahamian sea shells is of course the Queen or Pink Conch, Strombus
gigas. For details of its life cycle, go to my Conch
page. Below is a juvenile Conch or 'Roller' and a mature Conch with
a wide lip. The Conch is an important part of the Bahamian diet -
served as 'Crack' Conch, Conch Chowder or Conch Salad. The Conch is
a herbivore, feeding primarily upon Sea grass on the shallow banks
and in the lagoons inside fringing coral reefs.
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Adult wide-lipped Queen
Conch |
Juvenile 'Roller' Conch |
Conch are becoming uncommon in many parts of
the Caribbean - especially those with limited shallow waters. They
are also becoming less common in those parts of the Bahamas near
large centres of population. Legislation will soon be needed if the populations
of Conch are to stabilise.
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The West Indian Chank -
this big shell has a velvety covering or periostracum when
alive. This dries and peels off after the shell is removed
from the water. The Chank is recorded as having been used as a
trumpet by ancient peoples. In Bhutan, a sacred Chank appears
on the 10 chhertum coin. The Sinistral (left handed) sacred
Chank is found in the waters off Sri Lanka. In India the Chank
is used to make Bangles. It seems to have had no such use in
the Bahamas. |
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Banded Tulip Shell |
The much smaller Tulip shells
are predatory, feeding on smaller bivalve molluscs. As are the
Tun shells below. These have been recorded feeding on Holothurians
(Sea Cucumbers) which they ingest whole with their large
distended proboscis. |
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The Tun shells have an
enormous foot which cannot be withdrawn into the shell. A live Tun
shell is
shown above with its proboscis extended to the front. |
Atlantic Partridge Tun
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| There are hundreds of shell
species in the Bahamas, many of them small and relatively
insignificant. A close examination of the beach sand just
above the water line will reveal many of these, while many
more will be seen close to low tide level on rocks or around
the edges of rock pools. These include the Bleeding Tooth
Nerite - seen on the right. |
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On the beach also will be
the shells of dead bivalves. These are filter feeders for the
most part and are usually buried in the sand when they are
alive. On the left is the beautiful Sunrise Tellin, one
of the most colourful of the Bahamian bivalves. The famous
pink sands at Harbour Island off Eleuthera gain their colour
from shell fragments and the remains of coraline algae mixed
with the sand.
There are no really large
bivalves in the Bahamas. There is no Giant Clam in the Coral
reefs as in Pacific reefs, nor do the muddy creeks support a giant like the
northern Pacific Geoduck Clam.
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| The largest bivalve in the
islands is probably the Pen shell which grows to some seven
inches in length. This shell is sometimes found on the
beach where the Sea grass beds are close to shore. I have
found it on Montagu beach in Nassau. |
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Atlantic Thorny Oyster |
The scuba diver will see shells
that the casual tourist will never see. One of these is the
Atlantic Spiny Oyster which may be found attached to both hard
and soft Corals in water from 50 - 150 feet deep.
As this species is found beyond
the fringing reef, it is never found washed up on the beach
after death like many of the shells that inhabit the shallow
lagoons inside the reef.
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| Divers will also see the
strange little Flamingo Tongue shell, Cyphoma gibbosum
which feeds exclusively on sea fans. The colourful spotted
mantle of the mollusc is usually extended over the shell (on
right). The cleaned shell is a pinkish colour (on left).
All tourists and scuba divers should
ensure the future of these species by leaving live molluscs in
the sea, collecting only dead shells, for too many shell
species around the world are now threatened as a result
of over zealous collection. Note:
Some observant persons may see that images have been reversed - this
is for purely aesthetic reasons - they do not represent
sinistral or left-handed shells. |
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