Field of Science

Narona decaptyx: A Fossil Vampire

13.5 mm long specimen of Narona decaptyx, from Landau et al. (2012).

Narona decaptyx was described by Brown & Pilsbry (1911) from a single small, fusiform fossil shell, 11 mm in length, from the Gatun Formation of Panama, north of Panama City. They regarded the formation as probably Oligocene in age but Landau et al. (2012) later referred N. decaptyx to the upper Miocene. Until it's redescription by the latter, this species was only known from Brown & Pilsbry's original holotype; Landau et al. described further material from the Bocas del Toro region to the west of the original locality. Both the sites from which N. decaptyx are known are on the Caribbean coast of Panama.

Narona decaptyx is a member of the Cancellariidae, the nutmeg snails. Cancellariids are one of the smaller families of the great neogastropod radiation, the group that also includes such forms as whelks and cone shells. They generally have a more or less developed sculpture of criss-crossing spiral and axial ribs; the latticed pattern this produces is formally referred to as 'cancellate' and provides the source of the family's name. The most distinctive feature of Cancellariidae is their radula, a slender ribbon of long, flexible teeth arranged in a single row. How this radula functioned was long a mystery. Dissections of the gut of cancellariids failed to find any trace of solid food, and it was suggested they may be adapted to some form of suctorial feeding. Some authors suggested that cancellariids might feed by slurping up micro-organisms. Then, in the 1980s, one species of cancellariid Cancellaria cooperi was observed feeding on sleeping electric rays. The snail would cut incisions in the ray's skin, presumably with its radula, before inserting its proboscis to slurp up the fish's blood (O'Sullivan et al. 1987). Other cancellariids have been observed feeding on fluids from other invertebrates such as benthic molluscs or their egg masses.

Cancellaria cooperi feeding on an electric ray, copyright Clinton Bauder.

The genus Narona to which N. decaptyx belongs is now restricted to the north Pacific. In this respect, it is not unique. Cancellariids are poorly represented in the modern Caribbean fauna with only six species known from the sea's shallow waters but they were much more diverse there in N. decaptyx's time. However, following the rise of the isthmus of Panama, many cancellariid taxa once found widely in the tropical Americas became extinct for whatever reason on the eastern side of the divide. This happened regularly enough that the term 'paciphile' has been coined for referring to such taxa. A number of distinct waves of paciphile extinctions have been identified in the Caribbean cancellariid fossil record and they have been used to identify distinct chronological zones. Narona decaptyx became extinct as part of the GNPMU (Gatunian Neogene Paciphilic Molluscan Unit) 1 period. Other Narona species persisted in the Caribbean and Gulf of Mexico for longer, surviving into the Pliocene, but eventually they too succumbed to whatever dampened this family's prospects in the region.


Brown, A. P., & H. A. Pilsbry. 1911. Fauna of the Gatun Formation, Isthmus of Panama. Proceedings of the Academy of Natural Sciences of Philadelphia 63 (2): 336–373.

Landau, B., R. E. Petit & C. M. da Silva. 2012. The family Cancellariidae (Mollusca: Gastropoda) in the Neogene of the Bocas del Toro region, Panama, with the description of seven new species. Journal of Paleontology 86 (2): 311–339.

O'Sullivan, J. B., R. R. McConnaughey & M. E. Huber. 1987. A blood-sucking snail: the Cooper's nutmeg, Cancellaria cooperi Gabb, parasitizes the California electric ray, Torpedo californica Ayres. Biological Bulletin 172 (3): 362–366.

The Adrastini

Glyphonyx sp., copyright Mike Quinn.

For the subject of my next post, I drew the click beetle tribe Adrastini. Well, actually, I drew the tribe Synaptini but dibs on that name was originally called by a family of sea cucumbers so it seems that 'Adrastini' should be the tribe's proper name. I described click beetles, and the nature of their click, in an earlier post.

The Adrastini are one of those groups of animals for which there seems to be little known to discuss other than their general morphology. The more typical click beetles tend to be fairly uniform in their general appearance and are often not that easy to distinguish. Adrastins belong to the subfamily Elaterinae and resemble other elaterines in their deflexed mouthparts, arcuate prosternum, open mesocoxal cavities and tarsal claws without basal setae. They differ from other elaterines in having serrate tarsal claws according to Stibick (1979). Mind you, another related group, the Melanotini, are supposed to be distinguished by their pectinate claws and I'm not entirely sure what the difference between 'serrate' and 'pectinate' is supposed to be in this context.

The Adrastini are widespread though they seem to be absent from Australia. Several genera are recognised; one of these, Glyphonyx, is distinctly larger than the rest and includes about half the tribe's known species. As far as I know, the larva has never been described for any member of this group, so what they are doing ecologically remains a largely unknown quantity.


Stibick, J. N. L. 1979. Classification of the Elateridae (Coleoptera). Relationships and classification of the subfamilies and tribes. Pacific Insects 20 (2–3): 145–186.

The Stilt Bug Neides tipularius

Image copyright Janet Graham.

This is Neides tipularius, a widespread bug in the western part of the Palaearctic region. It feeds on a wide range of plants: I've seen references to it on grasses, on composites, or on chickweeds. It prefers drier regions such as coastal dunes or heaths.

Neides tipularius is a fairly typical member of the stilt bug family Berytidae. Berytids are more or less slender bugs in general but Neides is one of the more slender and long-legged ones. There are few other bugs with which a berytid could be confused; not only is there the wispy legginess to mark them, but berytids have distinctive long antennae with a short, spindle-shaped terminal segment forming a dark bobble at the end. Latreille (1802) did place N. tipularius in the genus Ploiaria, but that is now used for a group of small, long-legged assassin bugs with raptorial forelegs for catching prey.

Image copyright Sanja565658.

As with many other bugs, Neides tipularius exhibits polymorphism in wing development with flightless brachypters having narrower wings that only just reach the tip of the abdomen. Whether a given individual grows into a flying or flightless adult appears to be connected to the conditions under which they develop. Hot springs and summers have been noted to lead to increased numbers of macropterous adults.


Latreille, P. A. 1802. Histoire Naturelle, générale et particulière des crustacés et des insectes vol. 3. Familles naturelles des genres. F. Dufart: Paris.

Rust, Anyone?

At certain times of year, when the weather is warm, you may see patches of yellow or orange appear on plant leaves. It is often particularly notable on grass. These patches are known as rust and are the fruiting bodies of parasitic fungi. In some cases, they may be merely a nuisance or an eyesore. In other cases, their effects can be devastating. Rust fungi may cause enormous damage to commercial crops. One particularly nasty strain of the stem rust Puccinia graminis that goes by the label of TTKSK or Ug99 has been spreading through Africa and Asia since its discovery in Uganda in 1999, causing up to 100% losses in wheat crops where it hits. A similar strain of the same species was recently involved in outbreaks in southern Europe. And this rust can't just be covered over with a bit of bog.

Stem rust Puccinia graminis uredia on wheat, from the US Dept of Agriculture.

Puccinia is the largest genus of rusts with around 3000 known species (Liu & Hambleton 2010), infecting a wide range of host plants. Many rusts have complicated life cycles...or perhaps that should be 'insane'. Some of you may be aware that, until recently, mycologists (researchers of fungi) maintained a system of dual nomenclature that classified sexual and asexual forms of fungi separately, due to the difficulty in matching one to the other*. Rust fungi can have a life cycle involving a sexually reproducing stage and two different asexually reproducing stages on two different hosts, all of them distinct in appearance, so many rust fungal species could masquerade under no less than three distinct names! But then, some species might have simpler life cycles dropping one or more of the possible stages, and some might restrict their attentions to a single host. The difficulty of wrapping one's head around rust life cycles may perhaps best be conveyed by reproducing one paragraph from the review by Petersen (1974), which I invite you to look upon below in all its hideous hideousness:

*I believe that the botanical code of nomenclature was recently changed to no longer allow this set-up as a formal system, but I presume that it's going to take a long time to work that one through.

A complex system of nomenclature has been developed to quickly indicate the stages found in any particular life cycle in the rusts. While easily understood by students of the group with some experi- ence, the system at first appears bewildering. Those taxa which exhibit all five stages during their life history are called Euforms. They may be Heter-Eu- (infecting more than one host) or Aut-Eu- (occurring on a single host). In some rusts, the aecial stage is deleted, or the aecia and aeciospores are morphologically identical to uredia and uredospores, these organisms being termed Brachy-forms. All these forms are autoecious, thus enabling the "aut-" prefix to be dropped. For those organisms in which spermogonia and spermatia are missing, Maire used Cata- as a prefix, but this usage is rarely seen nowadays. When the uredial stage has been dropped, the organism is called an Opsis-form. This may be used as a prefix, such as Opsis- Gymnosporangium, or more commonly as a suffix, such as Gymno- sporangiopsis. Again, forms can be Heter-Opsis-, or Aut-Opsis-. If this life cycle also deleted spermogonia, it was dubbed Catopsis- by Maire. In more general terminology, rust fungi exhibiting chiefly teliospores (with or without spermogonia) are known as Micro-forms, but Maire again specified those which exhibited both telia and spermogonia as Hypo-forms. In these forms, the teliospores are normal in that they require a resting period before germination. In some taxa, teliospore-like propagules are produced which are lighter in color, exhibit thinner walls, and more obscure germ pores, and which require no resting period before germination, often germinat- ing in situ. These spores have been called leptospores, and the life cycle, otherwise identical to that of Micro-forms, is known as Lepto- form. Occasionally, only uredospores and teliospores are found (these sometimes are thought of as imperfect rusts in which other stages will hopefully be found), and these are called Hemi-forms. Finally, in some taxa the teliospores are cytologically similar to aeciospores, in which case the life cycle is called Endo-, the species with such structures often segregated in the genus Endophyllum.

Life cycle of stem rust Puccinia graminis, from US Dept of Agriculture.

A typical 'full' rust life cycle is the one gone through by stem rust, shown in the diagram above. Stem rust alternates between two hosts, grasses such as wheat (it also infects related species such as barley or rye) and barberry. Sexual reproduction occurs on barberry near the beginning of the growing season when haploid spores known as spermatia or pycniospores are produced from fruiting bodies called spermatogonia or pycnia. In Puccinia species, these spermatogonia are flask-shaped and tend to be evenly spaced across the host tissue; other rust fungi may produce more irregular and irregularly-spaced spermatogonia. At the sides of the flask's opening are protruding hyphae to which spermatia from other spermatogonia fuse. Now, in animals such as ourselves, fusion of sperm and ovum is usually immediately followed by fusion of their respective haploid nuclei to form the diploid daughter nucleus. In rusts, however, the haploid parent cells fuse but their nuclei do not. Instead, the daughter cell grows and divides as a dikaryotic organism with two nuclear lineages remaining associated but distinct in each cell. The dikaryotic mycelium produced from fusion of spermatium and receptive hypha gives rise to a fruiting body known as an aecium which in Puccinia is cup-shaped. The aecium produces its own spores that are shed to infect the alternate host, the grass, to which they gain access through the host's stomata. Germinating aeciospores grow into a mycelium that penetrates host cells, absorbing nutrients directly from the host cytoplasm. When the time comes for the next reproductive stage, the rust produces a compacted layer called a uredinium that gives rise to yet another spore type, urediniospores. Unlike aeciospores that travel from one host to another, urediniospores are able to re-infect the same host, giving rise to a new uredinial stage of the life cycle. This asexual sub-cycle continues indefinitely for as long as growing conditions remain good for the rust. When conditions deteriorate, the rust stops producing urediniospores and begins producing thick-walled teliospores that are able to persist through the cold winter. It is within the teliospores that the dikaryotic nuclei finally fuse, giving rise to daughter nuclei that then themselves undergo meiosis so the teliospore germinates at the beginning of the next season to release haploid basidiospores, that infect a barberry to begin the cycle anew.

Arum rust Puccinia sessilis aecia on leaf of Arum maculatum, copyright Velella.

Because of the need for two hosts in the life cycle, crop pests such as stem rust may potentially be controlled by eradicating the second host. However, first you have to know what to target. Stripe rust Puccinia striiformis is another significant pest of grass crops whose alternate host was not identified as barberry until 2010 (Jin et al. 2010). And in warmer climates where urediniospores can survive all year round, rusts may be able to persist asexually even without a suitable alternate host.


Jin, Y., L. J. Szabo & M. Carson. 2010. Century-old mystery of Puccinia striiformis life history solved with the identification of Berberis as an alternative host. Phytopathology 100: 432–435.

Liu, M., & S. Hambleton. 2010. Taxonomic study of stipe rust, Puccinia striiformis sensu lato, based on molecular and morphological evidence. Fungal Biology 114: 881–899.

Petersen, R. H. 1974. The rust fungus life cycle. Botanical Review 40 (4): 453–513.

Holding Forams Together

Nouria polymorphinoides, from

In past posts relating to the Foraminifera, I've made reference to the changes in classification undergone by this group over the years. Forams are unusual among unicellular organisms in producing a hard, often complex test that means they have both left an extensive fossil record and provided a number of characters on which to base a classification. However, there has been much disagreement over the relative attention due to particular features of the test. The classification used for forams in the Treatise on Invertebrate Paleontology by Loeblich & Tappan (1964), one of most influential sources in recent decades, made its primary divisions on the basis of the structure and chemistry of the test itself. Forams that produce a test by gluing together (agglutinating) sand particles and other foreign objects were treated as fundamentally distinct from those that secreted calcareous tests. Because the foram cell itself is amoeboid, there was an underlying assumption that the test architecture was too mutable to indicate anything more than low-level relationships.

However, there were some prominent inconsistencies with this assumption (Mikhalevich 2013). One is that the division between agglutinated and calcareous tests is not always perfect. Agglutinated forams might not secrete the bulk of the test themselves but they do secrete the cement used to hold the sand grains together, and there is a definite spectrum in the proportion of sand to cement used by a given foram. In some agglutinated forms, a distinct calcareous layer may underlie the agglutinated section of the test, and it is easy to envision how a progressive reduction in the proportion of agglutinated material could lead to the evolution of an entirely secreted test. This was not in itself fatal to the earlier system as it had generally been assumed that agglutinated forams were likely to represent a paraphyletic group. More problematic was the common appearance of foram species that were extremely similar in test architecture with the only really significant difference being that one was agglutinated and the other calcareous. This lead some authors to argue that whereas a small number of such cases might be accepted as the result of convergence, the abundance of such cases suggested that changes in test composition were more common than previously recognised. Molecular studies of forams are still in their infancy but have offered some support for the significance of test architecture, such as the division between globular and tubular forams (Pawlowski et al. 2013) that I referred to in an earlier post.

Liebusella goesi, from Foram Barcoding.

One effect of this change in focus is that the Mikhalevich (2013) classification divides the agglutinated forams between a number of groups that are not recognised in alternative systems. One such group is the Nouriida, known from the Cretaceous to the present day. Mikhalevich included the Nouriida in a larger group called the Hormosinana; at least one hormosinanan was placed by Pawlowski et al. (2013) at the base of the globular foram lineage. In contrast, Loeblich & Tappan (1964) included most of the nouriidans in the family Ataxophragmiidae, other members of which belong to the tubular forams. Nouriida and other Hormosinana are united by having the aperture of the test in a terminal position; in some nouriidans, it may be raised on a short neck. Nouriida differ from other hormosinanans in the arrangement of chambers in the test. In early stages they tend to be more or less trochospiral; with maturity, the number of chambers to a whorl decreases and the test may become biserial or uniserial. The two subfamilies recognised within the Nouriida by Mikhalevich differ in the internal structure of their chambers: Nourioidea have internally simple chambers but Liebuselloidea have the lumen of the chambers complexly subdivided.

I haven't found much about their ecological role; at least one modern species, Nouria polymorphinoides, seems to be not uncommon in shallower continental shelf waters worldwide. My general impression (just confirmed by asking a colleague who actually works on forams) is that agglutinated forams receive far less attention than calcareous ones. A big part of this is simply that they're harder to find: it takes a lot of practice to be able to pick out an actual agglutinated foram test from any other conglomeration of sand, and if they break apart during sample prep (which they often do) then there is little sign they were ever there to begin with.


Loeblich, A. R., Jr, & H. Tappan. 1964. Treatise on Invertebrate Paleontology pt C. Protista 2. Sarcodina: chiefly "thecamoebians" and Foraminiferida vol. 1. The Geological Society of America, and The University of Kansas Press.

Mikhalevich, V. I. 2013. New insight into the systematics and evolution of the Foraminifera. Micropaleontology 59 (6): 493–527.

Pawlowski, J., M. Holzmann & J. Tyszka. 2013. New supraordinal classification of Foraminifera: molecules meet morphology. Marine Micropalaeontology 100: 1–10.

Walruses, Sea Lions and Fur Seals

Adaptation to a primarily aquatic lifestyle has happened numerous times within mammals, but some groups have radiated more in this environment than others. One particularly well-known group of marine mammals is the pinnipeds, the seals and sea lions.

Australian sea lions Neophoca cinerea on a beach on Kangaroo Island, copyright Diver Dave.

Pinnipeds are highly modified for life in the water, with streamlined bodies and all four limbs modified into flippers. When I was young, many of the animal books that I read referred to pinnipeds as their own distinct order within the mammals. However, it has long been recognised that pinnipeds are derived from within the Carnivora and these days they are almost universally treated as a subgroup of the latter. Modern pinnipeds are divided between three families: the Phocidae ('true' seals), Otariidae (fur seals and sea lions) and Odobenidae (which has only one living species, the walrus Odobenus rosmarus). While some morphological analyses have argued for a relationship between the walrus and the Phocidae, the majority view treats the walrus and the Otariidae as together forming a clade Otarioidea, commonly referred to as the eared seals. There has historically also been some argument about whether the pinnipeds represent a single clade; some have argued for two separate origins, Otarioidea being related to bears whereas Phocidae were supposed to be closer to otters and weasels. However, the current majority supports a single origin for the group.

Northern fur seals Callorhinus ursinus, photographed by M. Boylan.

Eared seals differ from true seals in the possession of small external ears, and the ability to turn the hind flippers back under the body so that they can still function (if somewhat awkwardly) as feet when moving on land. I have seen Australian sea lions on coastal islands near Perth (there are boat tours that will take you to see them) and I can confirm that they can run along the beach at a surprising speed when they wish to. True seals have the hind flippers permanently directed behind them and so are forced to awkwardly belly-flop along when not swimming (doubtless as a result of this, true seals also differ from eared seals in that males lack an external scrotum). In the water, the hind flippers provide the main source of propulsion in true seals whereas eared seals get more of their thrust from the fore flippers (sea lions have been said to swim like penguins). As an aside, eared seals are also apparently unusual among mammals in that their milk completely lacks lactose. The lactose intolerant among you need not be denied dairy, you need only milk a walrus.

Mounted skeleton of Allodesmus sp., copyright Momotarou2012.

The earliest eared seals are known from the Miocene when they appear to have originated in the northern Pacific. Two extinct families from this place and period, the Enaliarctidae and Desmatophocidae, are commonly included in the Otarioidea, though it remains possible that either of these families should be placed outside the pinniped crown group, or closer to the true seals. The early Miocene Enaliarctidae differ from other otarioids in retaining differentiated premolars and molars (later forms have the cheek teeth uniform in appearance) and may well represent the ancestral form of the group. The mid- to late Miocene Desmatophocidae combined a rather Phocidae-like skull with a more Otarioidea-like post-cranium; the best-known genus Allodesmus had larger eyes than other otarioids and may have hunted in deep waters. One species of desmatophocid, Allodesmus sinanoensis, may have reached a length approaching five metres, making it larger than a modern walrus and rivalling the elephant seals in size. I highly recommend a series of posts on Allodesmus written a few years back by Robert Boessenecker (1, 2, 3, 4) that cover just about everything you might want to know about this animal.

Skull of Gomphotaria pugnax, from Robert Boessenecker.

Though only one walrus species is generally recognised in the modern fauna, the family was much more diverse in the past. However, most fossil Odobenidae lacked the tusks of a modern walrus and would have been more similar at a glance to sea lions. These early odobenids would have probably been generalist fish-feeders (Boessenecker & Churchill 2013). The modern walrus, in contrast, feeds primarily on bivalves. They don't crush the clam's shell but grab it with their lips and then suck powerfully enough that the meat is ripped out. Other than the tusks, the teeth of a modern walrus are small and weak; one close fossil relative, the Pliocene Valenictus chulavistensis, went so far as to lose the non-tusk teeth entirely. The tusks themselves are usually thought to function in display and the like rather than having any prominent role in feeding. However, it is an intriguing detail that the fossil whale Odobenocetops that converged in its feeding biology with walruses also possessed a large tusk. The non-tusk teeth were still used in feeding in the fossil clam-feeding walrus genera Dusignathus and Gomphotaria, which had a pair of large forward-directed tusks in both the upper and lower jaws.

Suckling South African fur seals Arctocephalus pusillus, copyright Robur.q.

The majority of living eared seals belong to the Otariidae, which have been divided in the past between the fur seals and sea lions. Fur seals tend to be smaller than sea lions and possess a dense layer of underfur. However, more recent phylogenetic studies (particularly molecular ones) have thrown this distinction out the window (e.g. Higdon et al. 2007). Instead, the northern fur seal Callorhinus ursinus of the north Pacific is probably the sister species to all other living otariids. Even the southern fur seals, generally placed in a single genus Arctocephalus, may not be monophyletic relative to the New Zealand sea lion Phocarctos hookeri (as a result, some authors have suggested resurrecting the genus Arctophoca for all southern fur seals other than the South African fur seal Arctocephalus pusillus). The South American fur seal Otaria flavescens may also be associated with this latter group. The two north Pacific sea lions, Steller's sea lion Eumetopias jubatus and the Californian sea lion Zalophus californianus, form a clade outside the southern otariids. The remaining species is the Australian sea lion Neophoca cinerea whose position has been harder to pin down: some analyses place it close to the New Zealand sea lion but others position it well away from all other southern otariids, possibly even outside all other otariids except the northern fur seal.

Walruses Odobenus rosmarus crowded on shore, from here.

Fur seals and sea lions were heavily hunted in the past for pelts and oil and some species remain endangered. Climate change poses a particular threat to cold-water species; for instance, recent years have seen significant contractions in walrus ranges, leading to dramatic crowding in the locations remaining. Conversely, the Antarctic fur seal Arctocephalus gazella, once feared extinct, has apparently exhibited a population explosion in recent decades, perhaps because lowered whale populations have led to more food being available for seals.


Boessenecker, R. W., & M. Churchill. 2013. A reevaluation of the morphology, paleoecology, and phylogenetic relationships of the enigmatic walrus Pelagiarctos. PLoS One 8 (1): e54311.

Higdon, J. W., O. R. P. Bininda-Emonds, R. M. D. Beck & S. H. Ferguson. 2007. Phylogeny and divergence of the pinnipeds (Carnivora: Mammalia) assessed using a multigene dataset. BMC Evolutionary Biology 7: 216.

Repenning, C. A., & R. H. Tedford. 1977. Otarioid seals of the Neogene. Geological Society Professional Paper 992: i–vi, 1–93, 24 pls.


Shell of Turris crispa crispa, copyright H. Zell.

At this point, I've made numerous references on this site to the gastropod family Turridae, discussing its members and non-members and alluding to its sordid history. So maybe I should set out the basics of the story properly.

The Conoidea are a diverse group of marine predatory gastropods with over 4000 known living species. They are best known for the production by many species of venom used to paralyse their prey, in some species being potent enought to threaten humans. In the majority of conoideans, this venom is delivered via a tooth that becomes detached from the radula and is held at the end of the retractable proboscis. Until relatively recently, Conoidea were commonly divided between three families. Two of these families, the Conidae (cone shells) and Terebridae (awl shells) were well defined and constrained. The third family was the Turridae, including by far the greater number of species but not really defined within Conoidea beyond 'the rest'. Many of 'the rest' were small, many were restricted to deep water, many were poorly known. Different systems were proposed over the years in an attempt to break the turrid mass into more manageable units but each system differed significantly from the next and no one system became universally accepted. Some authors would focus on the protoconch as their guide to classification, others would focus on the radula, others might call out features of the operculum. One author commented in 1922 that turrids were "considered by those who meddle with them to be more perplexing than any other molluscan family", and this complaint was still being upheld by Kilburn (1983) over sixty years later.

Though it had long been accepted that the 'turrids' probably did not represent an evolutionarily coherent group, it wasn't really until the advent of molecular phylogenies that things started falling into place. Puillandre et al. (2011) identified two main lineages within the Conoidea, leading to the dissolution of the original Turridae into no less than 13 families in order to maintain the already-established Conidae and Terebridae. Turridae in the strict sense was restricted to a much smaller clade of a bit over a dozen genera, sister to the Terebridae (Bouchet et al. 2011).

In contrast to the bewilderment of the original turrid array, Turridae sensu Bouchet et al. is a morphologically quite coherent group. They are more or less fusiform (spindle-shaped) shells, often with a narrow, high spire and relatively weak sculpture. Indeed, but for the fact that most tend to have a long siphonal canal at the base of the shell, they often bear a distinct resemblance to their sister group, the terebrids. The majority of turrids have a multispiral protoconch, indicating an extended, planktonic-feeding larval stage in development, but there are some species with a paucispiral protoconch indicative of direct development.

Radula of Xenuroturris legitima, from Kantor & Puillandre (2012); ct = central tooth.

The radula of turrids usually comprises three apparent teeth in each row. The central tooth is actually formed from three teeth (the original pointed central tooth and two plate-like lateral teeth) fused together; in some species the division between these teeth remains visible whereas in others the central tooth disappears entirely. The main business part of the radula is the single pair of marginal teeth which, as in other conoideans, are enlarged and modified for venom delivery. They have a distinctive 'duplex' form; in older publications, this was referred to as a 'wishbone' form because the tooth appears under light microscopy to be divided between two branches. After the advent of electron microscopy, it was discovered that these two 'branches' in fact represent the thickened margins of an undivided tooth. The larger of the two margins is mostly attached to the radular membrane with only the tip of the tooth being free; the smaller margin is held free of the radula. The thinner part of the tooth between the two margins forms a gutter along which venom can flow. However, the radula is placed in such a position that it cannot be protruded through the mouth in the manner of grazing gastropods. As with other conoideans, prey (in this case probably worms) is despatched through the use of a detached marginal tooth transferred to the end of the proboscis. However, whereas other conoideans such as cone shells may have the tooth functioning like a hypodermic syringe for delivering prey, turrids use their tooth to slash at the prey like a switchblade, with venom passively entering through the resulting cuts. The proboscis is then used to draw the prey back into the mouth, where the radula is used to grasp and swallow it, sucking the unlucky worm down the gullet like spaghetti.


Bouchet, P., Y. I. Kantor, A. Sysoev & N. Puillandre. 2011. A new operational classification of the Conoidea (Gastropoda). Journal of Molluscan Studies 77: 273–308.

Kantor, Y. I., & N. Puillandre. 2012. Evolution of the radular apparatus in Conoidea (Gastropoda: Neogastropoda) as inferred from a molecular phylogeny. Malacologia 55 (1): 55–90.

Kilburn, R. N. 1983. Turridae (Mollusca: Gastropoda) of southern Africa and Mozambique. Part 1. Subfamily Turrinae. Annals of the Natal Museum 25 (2): 549–585.

Puillandre, N., Y. I. Kantor, A. Sysoev, A. Couloux, C. Meyer, T. Rawlings, J. A. Todd & P. Bouchet. 2011. The dragon tamed? A molecular phylogeny of the Conoidea (Gastropoda). Journal of Molluscan Studies 77: 259–272.