Things with Stings…


Many invertebrate animals have ways to capture prey or defend themselves that result in an injection of a toxin into a target organism. Aquarists need to be aware of such structures or behaviors for two simple reasons: First, such an injection usually hurts. Second, such an injection may, in rare situations, be lethal. Either of these outcomes can really spoil one's whole afternoon, but at least in the latter case, the pain although often severe, is of limited duration.

Envenomation is the technical term for an injection of toxin, and there are really quite a wide variety of marine animals which have some method for doing this. Interestingly enough, many of the most sought-after animals in the aquarium hobby are capable of stinging some other animal. In this column, I will discuss in some detail the envenomation apparatus of some of the more commonly encountered stinging organisms, and will also discuss in passing some of the other animals that sting, even if they are rarely encountered in aquaria. The animals that actively sting really seem to be concentrated into two major groups: the Cnidarians, or corals, sea anemones, and jellyfishes; and the Mollusks, such as some snails. Other animals, such as fire worms and sea urchins, might have venom-laden spines, but they are generally passive in their delivery of the toxin. Some other animals, such as blue-ringed octopuses and flower sea urchins, bite to inject a toxin. It may be splitting hairs to some extent, but in this column I will assume that a bite is not a sting. Here I define a sting to be a puncture wound specifically designed to inject a venom below the epidermis; in effect, a sting is a hypodermal injection of venom.

For information on marine envenomations of all sorts follow this link.

The Cnidarian Nematocyst, An Intraepidermal Bomb

The corals, sea anemones, and jellyfishes are grouped together by scientists, in large part, because of their possession of a unique stinging apparatus. This structure is called a nematocyst. Nematocysts are invisible to the unaided eye, but are found by the millions in large cnidarians. Smaller animals, of course, have fewer of them simply because they have less surface area, and the number of nematocysts is dependant upon the extent of surface area. With only few exceptions, all cnidarians possess nematocysts, and those that lack them are thought to be descended from ancestors that once had them.

What is this thing called a nematocyst? Nematocysts are secretions of some peculiar cells found in all cnidarians. Most people tend to think that all cellular secretions are of a liquid or fluid nature, such as mucus or perhaps a digestive enzyme. Actually, such materials are simply solids dissolved in a fluid base, and there are many potentially solid materials secreted by individual cells. Such solid materials are often fluids which harden on contact with air or water, such as the protein that constitutes the tube of a feather duster worm. Other materials may be secreted as crystalline solids such as the spicules of a sponge. Nematocysts are proteinaceous capsules secreted in such a way as to have an internal thread-like structure. The capsular wall is very tough and resistant to deformation, yet it is permeable to water. Additionally, the contents of the capsule are quite concentrated. This means that there is a much higher relative abundance of water outside the capsule than there is in it. Such a disparity of water concentrations means that water tends to flow into the capsule by osmosis. This osmotic flow builds up a significant internal pressure in the capsules; the pressure has been measured at an equivalent of over 2000 pounds per square inch. The protein coating the capsule prevents the capsular contents from escaping.

Figure 1. A diagram of an undischarged nematocyst in a cell (left). A diagram of the structures found in a nematocyst (right). Compare with Figure 2.

Figure 2. A transmission electron micrograph of a section through a coral epidermal cell. Three nematocysts are visible, one at the lower left is only partially seen. Directly above it another nematocyst is visible. This one has been sliced through tangentially off of the midline of the nematocyst. Above this in the center of the figure is a nematocyst cut through the midline. Note the internal structures. Compare with Figure 1 to identify them; the thread spiraled around the inside of the nematocyst is particularly evident. This photograph is copyright 2002 by Eric Borneman and used with permission.

Under certain specific conditions, the most exterior portion of the capsule may rupture, releasing all of the internal contents. "Releasing" is much too mild a word to describe this process, though. It is not an exaggeration to refer to the contents as "exploding" from the cell. When the capsular contents are blown out, the internal thread is turned inside out and exits the capsule. Generally, the tip of the thread is hollow and the capsular contents will be sprayed from the tip of the thread.

It is impossible to watch the contents of the capsules themselves as they exit the nematocyst. However, the internal nematocyst thread may be filmed as it leaves the capsule using ultrahigh-speed photography, and is by no means easy to do. When it is done properly, however, a timed record of nematocyst discharge is available. From one such record, it was estimated that the tip of the nematocyst thread is forced out of the capsule at the astounding acceleration of 40,000g! Even though the tip of the thread is minute, with such acceleration driving it, it can punch through almost all biological surfaces, including some mollusk shells, arthropod exoskeletons, and human skin.

What makes the action of nematocysts even more "fun," if some happen to be triggered into your tissue, is that the cellular contents discharged by the nematocyst may be anything from toxins to digestive or lytic enzymes. Most of these materials are proteins. As far as the aquarist's body is concerned, these contents may do one of three things:

First, if they are discharged into thickened epidermis, such as on the palms of the hands, the thread may be too short to penetrate the dead epidermal layers, and the nematocyst discharges do nothing. In these cases, the aquarist may be considered lucky.
Second, if they are discharged into areas where the skin is thin, for example the inside of the forearm, they may cause pain and tissue damage. As an example, one person I worked with had the tentacles of a large fish-eating anemone from the Pacific Northwest brush across the inside of her arms in a display aquarium she was maintaining. The nematocysts left a trail of red pustules that developed into open ulcerative lesions that took about 2 months to heal.
Third, in such cases where the discharged proteins make it into the blood stream, there is the possibility of an allergic reaction. The materials discharged are foreign proteins, and their presence in the body initiates an immune response. This can, in some cases, develop into allergy, and further put the person at risk to severe allergic reactions, such as anaphylactic shock, if they get subsequently stung again. About 20 years ago, after a few months of working with sea anemones, I developed an allergic reaction to sea anemone stings. Consequently, I have to be quite careful around the sea anemones in my tanks.

Not all cnidarian nematocysts are dangerous, and some of the time they will not be of concern to aquarists. Nonetheless, many of the stony corals and most of the sea anemones that aquarists maintain have the capability of stinging, and in some cases this sting can be dangerous. Perhaps even more dangerous than the initial sting, is the possibility that that sting will inject foreign materials that will cause sensitization to subsequent stings. This may occur with the first sting, or it may never happen. However, if it does, such as with people who are sensitive to bee stings, the second sting may be lethal.

For descriptions and images of anemone stings from intertidal and subtidal anemones in Britain follow this link.

Here are some images of the results of stings from a jellyfish called the sea wasp.

The Australian box jelly, Chironex fleckeri, is responsible for more human fatalities than shark attacks. Here is a link to some information about it and some rather gruesome images.

The cnidarian nematocyst is a microscopic stinging apparatus that functions much like a small bomb, located in the tissue of the coral, jellyfish, or sea anemone. When each individual nematocyst is detonated on contact with the prey or some other organism, it sends a small amount of toxin into that animal. Generally, the discharge of a single nematocyst has very little effect; however, nematocysts don't exist singly. They are found in groups or bunches, and each may have several thousand nematocysts that all fire at once. The density of nematocysts at places in the epidermis of cnidarians may range upward to about 10,000 per mm (or about 6,000,000 per square inch).

Here are some links to information and illustrations of nematocysts:

hypnea.botany.uwc.ac.za
www.users.totalise.co.uk

The toxins found in nematocysts vary, and not all nematocysts inject toxins. However, when the cnidarians are specialized to capture and kill fish, their toxins are tailored to vertebrate physiology and will have some effect, to a greater or lesser degree, on humans and can be dangerous. All clownfish-hosting anemones will eat fish, as will some of the larger corals. The nematocysts from these animals are all potentially dangerous to aquarists, and the animals should be treated with caution.

Here is a link that discusses treatment for sea anemone and other cnidarian stings.

Slimy Snail Superstingers...

One of the ways that can be used to measure evolutionary success is to tabulate the number of species within a group. Those groups with a lot of species have exploited more ecological situations and habitats, and consequently the groups are considered to be successful. The Molluscan Class Gastropoda, or "the snails" is among the most successful of all animal groups; depending upon the "authority" chosen, there are an estimated 50,000 to 150,000 species of snails. Consider that there are only about 3,500 mammal species, or about 9,000 bird species, and it soon becomes apparent that even though they move at a snail's pace, these slimy animals have undergone an evolutionary diversification into an enormous number of species.

Most snails make their way through the world slowly crawling around on a broad foot rasping at food they encounter with a feeding organ called a radula. This radula can be thought of as a rough rasping tongue. In some snails, the radula contains teeth which are hardened with hematite and opal, and it can rasp through just about anything. In many others, such as the "turbo and trochid" grazers, the radula acts more like a leaf rake, sweeping diatoms into the mouth. However, there is one very large and diverse group of snails which have abandoned scraping their prey off the rocks, and have gone into the business of spearing their food with a hypodermic harpoon.

These are the snails in the group loosely called the "toxoglossa." The name is derived from the Greek roots "toxon" and "glossa" and means "bow tongue" as it was at one time thought they shot arrow-like teeth into their prey. Interestingly enough, the Greek term "toxicos," meaning "poison" derives from the same root, "toxon," as the ancient Greeks occasionally used poisoned arrows. One might be tempted to think the name for the snails should mean "poison-tongue," however, such a word would be "toxicoglossa," rather than "toxoglossa." In any case, the snails don't shoot arrows at their prey, nevertheless, the name stuck like an arrow into a bull's eye. Instead, they harpoon their prey and kill it so rapidly that only one small group of animals, the strombid conchs, has ever developed an escape response to them. All of the rest of their prey, including fishes, have no escape response to them, whatsoever. Neither do they have any tolerance to the venom. If they get stung, they die. It is worth remembering that for an escape response to evolve, some potential prey must escape and live to reproduce. If none do, then there will be no inherited response.

The venomous snails include, but are not limited to, the cone snails, and in fact some 20,000 different species have been put into the toxoglossan group, and only about 600 of these are truly Cone snails, or snails in the genus Conus. The others are put into several other groups, and some of these also kill their prey by stinging it, but none of these are dangerous to humans. Although the Cone snails are the most well-known of the stinging snails and are exclusively found in the tropics, the others are found in all seas, including the tropics, the polar seas, and the abyss.

For illustrations of venomous snails that are not cone snails, follow this link.

Both the nematocyst of the coral and the tooth of the snail are adapted to sting their prey. However, the similarities end there. Nematocysts are found inside of cells, while the venom and stinging apparatus of toxoglossan snails is a quite complex organ system made up of several different structures and organs:

The false mouth or rhynchostome; a vertically oriented slit at the front of the head. From the outside of the animal, it looks like the mouth, but it isn't. It opens into the proboscis chamber.
The proboscis chamber, or rhyncodeum, is a cavity within the head of the snail containing the mouth and retracted proboscis.
The proboscis, made of modified lips, forms a coaxial tube that surrounds the true mouth. When fully expanded, it can extend out of the rhynchostome and is often as long as the snail's shell.
The mouth, which opens internally inside the proboscis.
The mouth, or buccal, cavity is behind the mouth and contains the openings for the radular sac, venom gland, and salivary glands.
The radular sac contains the modified radula which secretes the harpoon-like teeth.
The teeth are formed in one part of the radular sac and stored like arrows in a quiver in the other part.
The venom gland opening into the buccal cavity just behind the radular opening.
The venom gland, which is a long tube located in the blood cavity inside the head. It terminates in the football shaped muscular bulb.


All of these structures constitute the venom apparatus of a toxoglossan snail.

Figure 3. A diagram of the head of a venomous snail, drawn from the right side, showing the venom apparatus as if the tissues of the right side of the head were transparent. The top view shows the proboscis withdrawn inside of the rhynchodeum or proboscis cavity. The drawing shows the proboscis as if it were cut through, but remember it surrounds the mouth as a tube. The bottom view shows the proboscis extended with the hypodermic tooth held in the tip.

Figure 4. This is a diagrammatic view of the head of a venomous snail, showing the proboscis extended as in the bottom diagram of the preceding figure. This view is from the bottom of the animal looking up. The venom apparatus, consisting of the muscular bulb and venom gland is visible, as are the radula and salivary glands. Other structures have been omitted for clarity.

Figure 5. The hypodermic tooth of a venomous snail from the N. E. Pacific, Oenopota turricula. The teeth of the tropical Conus are essentially the same in basic structure, but are about 10 times as large.

When one of these snails finds something it wishes to sting, a tooth is moved from the radular sac into the buccal cavity, where the barbed and bladed end is moved to a forward position. The tooth is then moved forward out of the mouth until the "hilt" of the spear-like tooth is gripped by a muscular sphincter at the tip of the proboscis. While this is happening, the venom gland secretes enough venom to backfill the buccal cavity and proboscis. Muscular contractions in the proboscis wall extend the proboscis through the false mouth, and for some distance outside the animal. The proboscis aims for the prey, with the tooth held in the tip, probably guided by sensory input from the tip of the proboscis as well as by sense organs near the mouth. When the prey is contacted, the tooth is rammed into the prey and the muscular bulb contracts, forcing venom into the prey. In some cases the force of envenomation is sufficient to blow venom completely through the prey! This venom is unbelievable in the way it acts. In the case of those Cone snails that spear fish, the fish dies effectively immediately, although it may twitch for a while. The snail then crawls up and engulfs the prey. I hope the reader will take the time to follow a couple of the links for a look at the movies of Conus spearing prey.

Most of these venomous snails are specialized predators that eat only one or a few species of polychaete ("bristle") worms. However, some species prey upon other snails, and only about a dozen species of Conus (out of about 600 total species of Conus) eat fish. In general, the sting of these worm and snail eaters is harmless, or at worst irritating, although repeated stings could lead to sensitization and allergic reactions, I suppose. The fish eating Cone snails, on the other hand, pack a venom that is amazingly lethal to all vertebrates, not just fish.

This fish-killing venom, called conotoxin, varies in its composition from Conus species to Conus species. All of these venoms, however, share some general properties. They are fast acting, and are a mixture of several different chemicals. Conotoxins are basically neurotoxins, and kill by disabling the prey's nervous system. Most animal neurotoxins are limited in their action; they typically disable only one part of nervous function. Generally, this is enough to rapidly immobilize the prey. The predator, often a snake, can follow the track of the prey if it has escaped, find it, and eat it.

Conotoxins are different. Effectively, they are multiphasic and kill nerves in every single different way that they can be killed. Animals stung by Cone snails don't usually go anywhere. This is good for the snail, as Conus has been described as being the slowest moving of all snails, although there is some doubt about that. Prey that die even a short distance from the snail would tend to be lost to the predator, so apparently natural selection has favored the development of these very potent venoms.

What really makes the venom and these snails interesting, of course, is that humans have died as a result of Conus stings. Just how many people have been killed by the snail is not known, but estimates range upwards of 50, or so, in the twentieth century.

For information on human fatalities see this link.

The problem with determining whether or not the person has died of the snail's sting, is that it is not immediately lethal. Humans are just a tad bit bigger than your standard goby, and so the action of the venom generally takes a while; say ten minutes to several hours. Death may be due to cardiac arrest and may mimic a heart attack. It is conceivable that many more human fatalities have occurred and were mis-identified as being due to some other cause.

In cases of known stings by fish-eating Cone snails, the majority of the human victims have died. Considering the very small amounts of venom being injected, this venom is one of the most lethal animal venoms known. Interestingly enough, the very lethality makes it attractive as a drug to treat some serious disorders, and a very significant amount of research is presently being done to modify the components of the venom so that it may be used to treat diseases.

For drawings of fish-eating Cones, including one eating fish, follow these links:

www.manandmollusc.net
www.starfish.ch

For information on the treatment of Conus stings, see these links:

www.pharmacology.unimelb.edu.au
www.emedicine.com

For information on Conotoxins and all things about Conus, including links to identification pages and movies of the snails killing fish, follow this link.

Of course, now that I have raised the potential spectre of aquarist-killing snails lurking in reef aquaria, I should note that the likelihood of this is vanishingly small. Of course, if it does occur and someone gets stung, I suppose the victim would take small comfort in those odds.

How To Identify a Potentially Deadly Snail

As any regular visitor to my "Ask Dr. Ron" forum knows, there are a lot of different snail species, and they are generally NOT easy to identify to that level. However, given that aquarists don't need to identify these particular animals to species, but rather just need to know enough to avoid them, the problem is simplified considerably.

Only Cone snails are potentially dangerous: all non-Cone snails are safe. So, if you can identify and remove Cone snails from your system, you won't have any worries. Here are some hints to help you identify a Cone snail.

Conus species are smooth-sided snails whose shell shape looks like a smooth ice-cream cone. There are no ridges and no sculpturing on the shell. It will typically be smooth, although there may be some narrow grooved lines in the shell.
All snails have an aperture, or opening, to the shell. This opening reaches one end (the front) of the shell. The opposite end is called the "spire" and terminates in the shell "apex." In many snails, the spire is elongated and tall. In the Cone snails, it is not. The spire is compressed and low, often flat. The shell really does look like a cone.
The shell aperture is typically slit shaped. It is not round, nor is it oval. In the dangerous species of Conus, the front part of the slit may be flared a bit, so that the animal can ingest fish.
Color is not a character used to discriminate these species. Some species of Cone snails come in almost all colors, and if you have one that has been introduced with live rock, it is likely to be covered with coralline algae or some other material. Others, mostly sand-dwelling species, are often brightly and beautifully colored, and these are often the dangerous ones.

If you find a snail that has all of these characteristics - or maybe even just one or two of them - and you remove and dispose of them, you won't have any trouble with stinging snails. If you do think you have one of these animals in your system, do not reach in and grab it bare handed! Use some tongs to grasp it and remove.

To verify your identification, use this link and then follow the internal links to Conus pictures and identification guides.

Now, it is also time for the disclaimer. Cone snails of any sort are very unlikely to appear in any aquaria. They are simply not collected to be sold to hobbyists. The only way they are likely to find their way into an aquarium is by being found as hitchhikers on live rock. Additionally, while there are about 600 species of Cone snails, only about a dozen are dangerous. The odds of finding any Cone snail at all are pretty slim, the odds of finding a dangerous one are really pretty small, and nothing to lose sleep about.

These two groups of animals, the toxoglossan snails and the cnidarians, are at the opposite ends of the spectrum of stinging animals. Structurally, they are very different, yet both groups have similarities. Neither corals nor Cone snails move much to find their prey, and both are adapted to use rapid acting chemicals to kill their prey. The cnidarians inject their prey with millions of tiny stings, each containing a minute amount of venom. The toxoglossans inject their prey with one or a few stings containing a small amount of highly toxic venom. In each case, this feeding mode has proven to be very successful. Cnidarians are common members of benthic marine communities throughout the world, and toxoglossan snails, which originated in the Mesozoic period, are rapidly speciating and are amongst the most successful groups of snails.


If you have any questions about this article, please visit my author forum on Reef Central.

Useful or Interesting References:

Nematocysts:

Aceret, T. L., P. W. Sammarco and J. C. Coll. 1995. Toxic effects of alcyonacean diterpenes on scleractinian corals. Journal of Experimental Marine Biology and Ecology. 188:63-78.

Ayre, D. J. and R. K. Grosberg. 1996. Effects of social organization on inter-clonal dominance relationships in the sea anemone Anthopleura elegantissima. Animal Behaviour. 51:1233-1245.

Brand, D. D., R. S. Blanquet and M. A. Phelan. 1993. Collagenaceous, thiol-containing proteins of cnidarian nematocysts: A comparison of the chemistry and protein distribution patterns in two types of cnidae. Comparative Biochemistry and Physiology B Comparative Biochemistry. 106:115-124.

Gitter, A. H. 1995. Imaging of electrically induced fast motion by video microscopy and triggered flash illumination. Journal of Neuroscience Methods. 63:37-41.

Gitter, A. H. and U. Thurm. 1996. Rapid exocytosis of stenotele nematocysts in Hydra vulgaris. Journal of Comparative Physiology a Sensory Neural and Behavioral Physiology. 178:117-124.

Goldberg, W. M. and G. T. Taylor. 1997. Coelenterate cnidae capsules: disulfide linkages revealed by silver cytochemistry and their differential responses to thiol reagents. Biological Bulletin (Woods Hole). 192:1-16.

Hidaka, M. 1985. Nematocyst discharge, histoincompatibility, and the formation of sweeper tentacles in the coral Galaxea fascicularis. Biological Bulletin. 168:350-358.

Hidaka, M. and I. Miyazaki. 1984. Nematocyst discharge and surface of the ordinary and sweeper tentacles of a scleractinian coral, Galaxea fascicularis. Galaxea. 3:119-130,illustr.

Hidaka, M. and K. Yamazato. 1984. Intraspecific interactions in a scleractinian coral, Galaxea fascicularis: induced formation of sweeper tentacles. Coral Reefs. 3:77-86,illustr.

Holstein, T. and Tardent, P. 1984. An ultrahigh-speed analysis of exocytosis: Nematocyst discharge. Science. 223: 830-833.

Lotan, A., L. Fishman, Y. Loya and E. Zlotkin. 1995. Delivery of a nematocyst toxin. Nature. 375:456.

Peach, M. B. and O. Hoegh-Guldberg. 1999. Sweeper polyps of the coral Goniopora tenuidens (Scleractinia: Poritidae). Invertebrate Biology. 118:1-7.

Pires, D. O. 1997. Cnidae of scleractinia. Proceedings of the Biological Society of Washington. 110:167-185.

Pires, D. O. and F. B. Pitombo. 1992. Cnidae of the Brazilian Mussidae (Cnidaria: Scleractinia) and their value in taxonomy. Bulletin of Marine Science. 51:231-244,illustr.

Russell, T. J. and G. M. Watson. 1995. Evidence for intracellular stores of calcium ions involved in regulating nematocyst discharge. Journal of Experimental Zoology. 273:175-185.

Schmidt, G. H. 1982. Replacement of discharged cnidae in the tentacles of Anemonia sucata. Journal of the Marine Biological Association of the United Kingdom. 62:685-692.

Shostak, S. and V. Kolluri. 1995. Symbiogenetic origins of cnidarian cnidocysts. Symbiosis. 19:1-29.

Thomason, J. C. and B. E. Brown. 1986. The cnidom: an index of aggressive proficiency in scleractinian corals. Coral Reefs. 5:93-102,illustr.

Thorington, G. U. and D. A. Hessinger. 1996. Efferent mechanisms of discharging cnidae: I. Measurements of intrinsic adherence of cnidae discharged from tentacles of the sea anemone, Aiptasia pallida. Biological Bulletin (Woods Hole). 190:125-138.

Watson, G. M. and R. N. Mariscal. 1984. Calcium cytochemistry of nematocyst development in catch tentacles of the sea anemone, Haliplanella luciae (Cnidaria: Anthozoa), and the molecular basis for tube inversion into the capsule. Journal of Ultrastructure Research. 86:202-214.

Watson-Glen, M., P. Mire and R. Hudson-Renee. 1998. Frequency specificity of vibration dependent discharge of nematocysts in sea anemones. Journal of Experimental Zoology. 281:582-593.

Weber, J. 1995. The development of cnidarian stinging cells: maturation and migration of stenoteles of Hydra vulgaris. Roux's Archives of Developmental Biology. 205:171-181.

Westfall, J. A., D. D. Landers and J. D. McCallum. 1998. Different nematocytes have different synapses in the sea anemone Aiptasia pallida (Cnidaria, Anthozoa). Journal of Morphology. 238:53-62.

Zamponi, M. O. and M. Archa-Tellechea. 1988. The nematocysts and their relation with the capture of food. Physis Seccion a Los Oceanos Y Sus Organismos. 46:73-86.

Toxoglossan Snails:

Barinaga, M. 1990. Science digests the secrets of voracious killer snails. Science. 249:250-251.

Green, J. L. and A. J. Kohn. 1989. Functional morphology of the Conus proboscis (Mollusca: Gastropoda). Journal of Zoology, London. 219:487-493.

Kantor, Y. I. 1988. K Voprocu o zhakladkya radulii u zhemerunov nekotorukh bryuukhonogukh mollyuoskov. Doklady, Academy Nauk SSSR. 299:247-249.

Kantor, Y. I. and A. V. Sysoev. 1989. The morphology of toxoglossan gastropods lacking a radula, with a description of new species and genus of turridae. Journal of Molluscan Studies. 55:537-549.

Kantor, Y. I. and J. D. Taylor. 1994. The foregut anatomy of Strictospira paxillus (Reeve, 1845) (Conoidea:Strictospiridae). Journal of Molluscan Studies. 60:343-346.

Kohn, A. J. 1956. Piscivorous gastropods in the genus Conus. Proceedings of the National Academy of Sciences of the United States of America. 42:168-171.

Kohn, A. J. 1958. Recent cases of human injury due to venomous marine snails of the genus Conus. Hawaii Medical Journal. 17:528-532.

Kohn, A. J. 1959. The ecology of Conus in Hawaii. Ecology. 29:47-90.

Kohn, A. J. 1966. Food specialization in Conus in Hawaii and California. Ecology. 47:1041-1043.

Kohn, A. J. 1967. Environmental complexity and species diversity in the gastropod genus Conus on Indo-West Pacific reef platforms. American Naturalist. 101:251-259.

Kohn, A. J. 1968. Microhabitats, abundance and food of Conus on atoll reef in the Maldive and Chagos Islands. Ecology. 49:1046-1062.

Kohn, A. J. 1972. Radula tooth structure in the Gastropod Conus imperialis elucidated by scanning electron microscopy. Science. 176:49-51.

Kohn, A. J. 1981. Abundance, diversity, and resource use in an assemblage of Conus species in Enewetak Lagoon. Pacific Science. 34:359-369.

Kohn, A. J. 1983. Microhabitat factors affecting abundance and diversity of Conus on coral reefs. Oecologia (Berlin). 60:293-301.

Kohn, A. J. 1985. Evolutionary ecology of Conus on Indo-Pacific Coral Reefs. Proceedings of the Fifth International Coral Reef Congress, Tahiti. 4:139-144.

Kohn, A. J. 1990. Tempo and mode of evolution in Conidae. Malacologia. 32:55-67.

Kohn, A. J. and J. W. Nybakken. 1975. Ecology of Conus on Eastern Indian Ocean Fringing Reefs: Diversity of Species and Resource Utilization. Marine Biology. 29:211-234.

Kohn, A. J., E. R. Myers and V. R. Meenakshi. 1979. Interior remodeling of the shell by a gastropod mollusc. Proceedings of the National Academy of Sciences of the United States of America. 76:3406-3410.

Miller, J. A. 1989. The toxoglossan proboscis: structure and function. Journal of Molluscan Studies. 55:167-181.

Olivera, B. M., J. Rivier, C. Clark, C. A. Ramilo, G. P. Corpuz, F. C. Abogadie, E. E. Mena, S. R. Woodward, D. R. Hillyard and L. J. Cruz. 1990. Diversity of Conus neuropeptides. Science. 249:257-263.

Perron, F. E. and A. J. Kohn. 1985. Larval dispersal and geographic distribution in coral reef gastropods of the genus Conus. Proceedings of the Fifth International Coral Reef Congress. 4:95-100.

Robinson, E. 1960. Observations on the toxoglossan gastropod Mangelia brachystoma (Phillipi). Proceedings of the Zoological Society of London. 135:319-338.

Shimek, R. L. 1975. The morphology of the buccal apparatus of Oenopota levidensis (Gastropoda: Turridae). Zeitschrift für Morphologie der Tiere. 80:59-96.

Shimek, R. L. 1983. Biology of the Northeastern Pacific Turridae. I. Ophiodermella. Malacologia. 23:281-312.

Shimek, R. L. 1983. The biology of the Northeastern Pacific Turridae. II. Oenopota. Journal of Molluscan Studies. 49:146-163.

Shimek, R. L. 1983. The biology of the Northeastern Pacific Turridae. III. The habitat and diet of Kurtziella plumbea (Hinds, 1843). The Veliger. 26:10-17.

Shimek, R. L. 1984. The biology of the Northeastern Pacific Turridae. IV. Shell morphology and sexual dimorphism in Aforia circinata (Dall, 1873). The Veliger. 26:258-263.

Shimek, R. L. 1986. The biology of the Northeastern Pacific Turridae. V. Demersal Development, synchronous settlement and other aspects of the larval biology of Oenopota levidensis. International Journal of Invertebrate Reproduction and Development. 10:313-337.

Taylor, J. D., Y. I. Kantor and A. V. Sysoev. 1993. Feeding mechanisms, relationships and classification of the Conoidea (=Toxoglossa)(Gastropoda). Bulletin of the Natural History Museum, London. 59:125-170.




ReefKeeping Magazine™ Reef Central, LLC. Copyright © 2002

Things with Stings… ReefKeeping.com