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"Mollusc of the Moment"
Visit Schooner Specimen Shells
by Ross Mayhew creator of The Mollusc of the Moment Articles
Species: Turris babylonia Linne, 1758 & Leinardia cf corticea (Hedley, 1922)
English Name: None universally valid, really!
Image: Sony Mavica digital camera.
.....These two handsome shells are here to represent the largest and most diverse family of molluscs on the planet: the Turridae1. In any given marine locality, turrids2 are usually about 15% of the total number of molluscan species, meaning there are about 8,000 species known to science now, and possibly 20,000 species in total. The family as a whole, is IMMENSELY diverse and confusing: there are hundreds of genera (the groups species are placed in, below the family level), and the family is commonly called a "taxonomic nightmare" (taxonomy is the relationship between different species): if you meet a Turrid taxonomist and they appear sane, they are probably faking it!!
Note 1: "Turridae" may
not actually be a single family - recently, taxonomic researchers
(i.e., people that try and figure out the relationships between species
and groups of species - see the Man and Mollusc article on Taxonomy) have proposed
splitting it up into several smaller families, all closely related.
However, for the sake of this article we shall treat them all as members
of the same enormous family!)
.....The two featured species show the size extremes that occur in the family, which lives in almost all habitats in the world's oceans, including the warmest, coldest and deepest that can support shell-bearing molluscs3. The large one, Turris babylonia Linne, regularly grows to over 100mm (4"), while the tiny one, Leinardiacf4. corticea (Hedley) is fully adult at 3 to 4mm.
Note 3: There are some places in
the ocean where shells can't be formed, so molluscan families which
create shells of calcium carbonate (CaCO3 - one calcium,
one carbon, and three oxygen atoms) - like Turridae, can't live there.
One reason why an a shell cannot survive in a particular habitat is
acidic environments created by rotting organic matter: dead sea life
falling into an area where there is not enough current to refresh
the water, which consumes all the oxygen that normally prevents acids
from forming. Also, since calcium carbonate is dissolved more
quickly at high pressures and cold temperatures, so in the VERY deep
ocean, molluscs cannot form shells, since they cannot form shells
or protect them, since they are dissolving so fast!!
.....Turrids are members of the carnivorous (meat eating) superfamily5 called Conacea, whose most famous inhabitants are the colorful Conidae, which number about 600 species. They are easily distinguished by the presence of a deep notch, appropriately called the "Turrid notch", very close to the top of the terminal (i.e., the last) whorl of the shell. They make a living by the fascinating method of "harpooning" their prey using a highly modified hollow radula6, which contains a powerful nerve toxin which quickly paralyzes the hapless victim. Unlike most gastropods, they only have a few radula teeth (only one is necessary to paralyze dinner), so they must be quite accurate if they don't want to use up a lot of energy producing more of them all the time.
the level of organization just above the familiy level -if you read
the Taxonomy article,
you might recall that all living organisms are grouped into different
levels or groupings, based on how similar they are to each other -
species are grouped into genera, genera into families, families into
orders, then comes class, phylum and Kingdom. Each level
may be further divided into "sub" and "super"
groupings - sub means below, while super means above. So, a
"superfamily" is the next grouping above family, but below
order. The superfamily Conoidea contains 3 families: Conidae,
the cone shells, Turridae, and Terbridae.
.....Most Turrids eat Polychaete worms, while a few eat other molluscs. They are often highly prey specific - i.e. each species of Turrid dines upon only a few species of prey - indeed, most of them will only eat a single prey species!! . This means that a great many Turrid species can live in the same habitat, side by side, because they each hunt a different prey7!! In a single handful of deep-water mini and micro8 shells from Punta Engano (a small part of Cebu Island in the Philippines, famous for its many shell dealers), for example, washed from Spondylus and coral, one can find up to 100 species of Tiny Turrids.
Note 7: All living organisms can
be divided into two general camps: "specialists" that
eat make a living by very narrow means, such as by hunting only a
few species, or by tolerating only a narrow range of temperature,
salinity, light intensity, etc. - and "generalists" who
can eat a wide variety of different foods, or who can tolerate a wide
variety of conditions. A good example of a generalist would
be be our species - good old Homo Sapiens: although not all
foods are best for our health, we can eat a HUGE variety of things,
from dead animals of many kinds, to starchy grains, to dandelion leaves
and broccoli!! We can also, with the help of our clever brains, opposable
thumbs and ability to articulate many different sounds, manage to
survive in almost all land-based habitats on the planet, from tropical
rain forests to Siberia or northern Canada. The Turrids are
an example of extreme specialization - with regards to the food they
eat, at least.
.....One of the things that make the family so intensely confusing is that even within the same species there is an incredible amount of variation, so that it is difficult to tell where one species' variation ends and a closely related species' variability begins!! The best way to reliably distinguish very similar species is to examine the radulae6, which due to their extreme prey specificity (i.e., selectivness), are quite distinct and consistent : they do not vary much - as opposed to the radulae of families of generalists7 such as Buccinidae, which are virtually useless in telling species apart, since it is not necessary for a Buccinid to produce radulae which are really consistent in their shape: as long as they can drill through a variety of different shell types, a Buccinid is happy as a clam!! Unfortunately, Turrid radulae are notoriously difficult to extract from the animal, being small, fragile (recall they are hollow, to hold the venom) and few. As a result of the combination of these factors, the Turridae family (or family complex - take your pick!) is, and is likely to remain one of the least studied and most poorly understood groups of molluscs: it takes a special breed of person to spend years or decades of their lives studying such a confusing and frustrating crowd!! (but, if you are looking for a REAL challenge in life, with complex science and controversy galore, Turrid Taxonomy just MIGHT be for you..... :--)).
Note 9: Until nearly the middle of the 20th Century, the so-called "Western" world (first used to refer to Rome, which was west of the middle (Persia, Israel, etc.) and far (India and China) east, then later generalized to include all of Europe and its most prosperous colonies, especially North America and Oceania (New Zealand and Australia) was the only culture on the planet that sought to systematically measure, objectively study, and categorize in hierarchical (i.e., by levels - as in taxonomy!) ways everything in the natural world - i.e., they were the only culture to use the "scientific" method that we use today, to understand nature. This means that up until around 1930 or so, very few non-Westerners (Orientals, Africans, Indians, northern Asians and aboriginal cultures worldwide) were involved in such pursuits as describing and naming species of plants, animals and other forms of life - and those that were, using systems of organization other than the one developed by Linneus in 1758, were either unknown to Western scientists, or ignored. Also, since minority groups were far less likely to gain a university education back then, nearly all of the names you will see attached to any achievement or endeavor in the realms of science (i.e., the way our "Western" culture seeks to understand the universe!) are European - and why it seems odd to see "Kira and Ito, 1955" behind a species of mollusc, denoting the authors of the article where the beastie was first described, given a name, and first categorized as to genus and family :-)). (Sorry for such a long note, but I just realized this myself a few minutes ago and I wanted to share the revelation!!)
.....No other specimens were known until the early 1930's when several, exactly comparable, were fished up in Japanese waters; it was no longer regarded as a monstrosity and its systematic position was duly established as a full-fledged Turrid a few years later. As more specimens were found, their commercial value escalated and high prices were paid for them until the 1950's: from then on they were common enough to be obtained quite reasonably. Currently, the main sources are from the Philippines, notably from Manilla Bay, and from deep water off Taiwan. (Note: most of the above information about this exquisitely-shaped species was found at the famous web site of the Jacksonville Shell Club, which has a wonderful variety of articles about seashells and landsnails, and is WELL worth checking out!! The specimen below, however, was imaged in Timberlea, New Scotland, by yours truly.)
Thatcheria mirabilis Angas, 1877
"Japanese Wonder Shell"
Taiwan, trawled about 80m on sand.