Conomurex luhuanus

Strawberry conch
	Five views of a shell of the Strawberry conch, Conomurex luhuanus
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Subclass:	Caenogastropoda
Order:	Littorinimorpha
Superfamily:	Stromboidea
Family:	Strombidae
Genus:	Conomurex
Species:	C. luhuanus
Binomial name
	Conomurex luhuanus; (Linnaeus, 1758)
Synonyms
	Strombus luhuanus Linnaeus, 1758

Last updated October 07, 2023

Conomurex luhuanus, commonly known as the strawberry conch or tiger conch, is a species of medium-sized sea snail, a marine gastropod mollusk in the family Strombidae, the true conchs.^[1]C. luhuanus is found in sandy habitat among corals in the Indopacific region. They feed on algae or detritus, move with a modified foot, and have complex eyes compared to other gastropods.^[2]

Shell description

The shell of C. luhuanus ranges from a more common length of 5 cm, to a maximum length of 8 cm.^[3]

C. luhuanus is often mistaken for a cone snail, mainly because of the conoidal outline of its shell, which is relatively unusual among the Strombidae. Its stromboid notch, though not as conspicuous as observed in many species that used to belong to Strombus (such as Lentigo lentiginosus ), is deep and easily distinguished. The interior may be slightly lirate.

The external color of the shell can be either white with an orange, brown/tan pattern of blotches, or completely brown/white. The interior is usually colored strong orange, red or pink, and the inner lip border is black or chocolate brown.^[3]

Phylogeny

Strombidae

Terebellum terebellum

	Eustrombus

	Aliger

Phylogeny and relationships of Strombidae according to Simone (2005)^[4]

The phylogenetic relationships among the Strombidae have been mainly accessed on two occasions, by Simone (2005)^[4] and Latiolais (2006),^[5] using two distinct methods. Simone proposed a cladogram (a tree of descent) based on an extensive morpho-anatomical analysis of representatives of Aporrhaidae, Strombidae, Xenophoridae and Struthiolariidae, which included C. luhuanus.^[4]

With the exception of Lambis and Terebellum , the remaining taxa were previously allocated within the genus Strombus , including C. luhuanus. However, according to Simone, only Strombus gracilior , Strombus alatus and Strombus pugilis , the type species, remained within Strombus, as they constituted a distinct group based on at least five synapomorphies (traits that are shared by two or more taxa and their most recent common ancestor).^[4] The remaining taxa were previously considered as subgenera, and were elevated to genus level by Simone in the end of his analysis. The genus Conomurex , in this case, only included C. luhuanus.^[4]

In a different approach, Latiolais et al. (2006) proposed a cladogram based on sequences of nuclear histone H3 gene and mitochondrial cytochrome-c oxidase I (COI) gene showing phylogenetic relationships of 32 species that used to belong to the genus Strombus and Lambis , including Conomurex luhuanus (= Strombus luhuanus).^[5] All species in this cladogram are still given under their original names in Strombus and Lambis.

Habitat and ecology

C. luhuanus dwells in sandy substrate in tropical habitats, such as the Great Barrier Reef and southern Papua New Guinea.^[2] They often form colonies that move together over long periods of time. Two types of colonies have been described: colonies of juveniles that are made up of conch of the same size-class, and colonies of mixed age-classes that contain individual conch of a spectrum of ages, although within the colony separation based on age still persists. C. luhuanus are herbivores or feed on detritus.^[2] They use their proboscis to pick up sand which they may then swallow or eat algae from. Strombus also have sensory tentacles at the end of their eyestalks which may play a role in chemically sensing the presence of nearby food. The sensory tentacles may also be important in detecting predators, such as carnivorous snails.^[6] Unlike many snails that move by slowly creeping along their terrain, members of the Strombus family move with an awkward leaping motion as they thrust off the sea floor with their modified foot.^[7] This leaping motion is also used to quickly escape from predators.^[6]

Phylogeny and relationships of Strombidae according to Latiolais (2006)^[5]

Reproduction

C. luhuanus form mating aggregations of copulating individuals were males and females compete for reproduction opportunities.^[2]

Vision

The eyes of members of the Strombus family are positioned at the ends of eye stalks and typically have a diameter of about 1.5-2.5 mm, which is large compared to their body size.^[8] The eye stalks extend from two notches in the shell.^[7] The eye of Strombus contains a spherical lens, a cornea, a pupil with a pigmented iris surrounding it, a vitreous body, and a cup-shaped retina.^[9] In contrast, some other gastropods only possess small open eyes containing a gelatinous substance.^[10] The retina is made up of several layers. The first layer, located adjacent to the vitreous body, is primarily composed of the processes of photoreceptor cells. This layer is approximately 180 um thick. The next layer is characterized by an abundance of dark pigment granules. The following layer contains the cell bodies of different cell types, and the last layer consists of neuropil. It is from the neuropil layer that the optic nerve projects in several small branches that eventually merge to form a single nerve fiber.^[9]Strombus has almost 100,000 photoreceptors, whereas some nudibranchs merely have five.^[11] Three distinct cell types have been described in the retinas of C. luhuanus, one of which is a photoreceptor, another which is a glial cell, and the last which may be a second type of photoreceptor.^[9] Only one type of visual pigment has been identified in C. luhuanus, suggesting that they do not possess color vision.^[12]

Electrophysiological recordings that measure electrical impulses, or action potentials, from neurons have been used to study the neural processing of visual information from the eye of C. luhuanus. When eyes adapted to the dark were shown brief flashes of light, a cornea-negative potential was evoked. This response was termed the "on" response. When light was presented to the dark-adapted eye for a longer period of time, the extracellular retinal potential (ERG) recordings showed the cornea-negative potential declined until a steady-state was reached. Then, the steady-state was maintained until the light stimulus ceased and the potential returned to baseline. Finally, a third type of response that fired at the cessation of light stimulus was observed and termed the "off" response. These different waveform responses could indicate that C. luhuanus is capable of complex neural processing involving excitation, inhibition, and synaptic inhibition. The "on" response could be due to excitation of the optic nerve in response to depolarizing photoreceptors, while the decline to steady-state potential could be a sign of synaptic inhibition, and the "off" activity could indicate release from light-promoted inhibition.^[12]

The light-promoted "off" potentials were found to be sensitive to anesthesia by magnesium chloride, with repetitive "off" potentials eliminated within minutes of being introduced to the magnesium chloride solution. However, the light-promoted "on" potentials were not affected by the magnesium chloride and would continue firing over an hour after being immersed in the magnesium chloride solution. These results could indicate that nerve fibers that are responsible for "off" stimuli are regulated by chemical synapses, which can be inhibited by magnesium.^[13]

It is not entirely clear why C. luhuanus evolved such well-developed eyes. Usually eyes of this complexity are found on predators that move quickly through their environment looking for prey, not in slow-moving herbivorous creatures such as C. luhuanus.^[14] One study suggests that the eyes are important for coordination in the escape response of Strombus. When conch were blinded, they showed an increased probability of leaping nearer to the predator instead of away from it.^[15] More work remains to be done on the purpose of the eyes, however.

Regeneration

Another remarkable feature of the eyes of Strombus luhuanus is that they are capable of regeneration following amputation. The first step of regeneration following severance of the optic nerve is the formation of an eye cup as the epithelium adjacent to the cut folds inward. This occurs within a day after the optic nerve is cut. The eye cup is closed by day three, and at this stage it resembles an embryonic eye. The diameter of the eye continues to increase, and meanwhile the cells of the eye differentiate to form the different layers in the retina. When the diameter of the eye reaches about 0.8 mm (after about 15 days), the retina looks like a mature adult eye. The eye will continue to grow until it becomes fully sized, with a diameter of 2 mm, which can take several months. Size, age, sex, nutritional state, or whether the left or right eye is amputated does not have a substantial influence on the regenerative prospects of the eye.^[16]

Tiger conch (C. luhuanus) Tigerconch.jpg — Tiger conch (C. luhuanus)

In gastropod eye regeneration, the degenerating nerve is important for the formation of the new eye. New axons leave the eye cup and bundle together to form the optic nerve. The new nerve fibers seem to be attracted to the previous optic nerve, and grow down it until they make contact with the cerebral ganglion.^[17]

Electroretinograms (ERGs) have been used to monitor neuron activity in the developing eye of C. luhuanus over the course of the eye's development. The ERGs of the regenerating C. luhuanus eye grow increasingly complex as the eye matures. During the first week of regeneration, a simple "on" peak was recorded, and steady-state potentials were observed in response to prolonged illumination. When the eye reached about 0.4 mm in diameter, an "off" response was observed occasionally. At a diameter of 0.6 mm, rhythmic ERG "off" responses were detected. By 0.8 mm in diameter, the ERGs of the regenerated eye resembled that of a mature adult eye, with two distinct cornea-negative "on" potentials and rhythmic "off" potentials.^[16]

Related Research Articles

The retina is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then processes that image within the retina and sends nerve impulses along the optic nerve to the visual cortex to create visual perception. The retina serves a function which is in many ways analogous to that of the film or image sensor in a camera.

<span class="mw-page-title-main">Eye</span> Organ that detects light and converts it into electro-chemical impulses in neurons

Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and convert it into electro-chemical impulses in neurons (neurones). In higher organisms, the eye is a complex optical system which collects light from the surrounding environment, regulates its intensity through a diaphragm, focuses it through an adjustable assembly of lenses to form an image, converts this image into a set of electrical signals, and transmits these signals to the brain through complex neural pathways that connect the eye via the optic nerve to the visual cortex and other areas of the brain. Eyes with resolving power have come in ten fundamentally different forms, and 96% of animal species possess a complex optical system. Image-resolving eyes are present in molluscs, chordates and arthropods.

<span class="mw-page-title-main">Electroretinography</span>

Electroretinography measures the electrical responses of various cell types in the retina, including the photoreceptors, inner retinal cells, and the ganglion cells. Electrodes are placed on the surface of the cornea or on the skin beneath the eye to measure retinal responses. Retinal pigment epithelium (RPE) responses are measured with an EOG test with skin-contact electrodes placed near the canthi. During a recording, the patient's eyes are exposed to standardized stimuli and the resulting signal is displayed showing the time course of the signal's amplitude (voltage). Signals are very small, and typically are measured in microvolts or nanovolts. The ERG is composed of electrical potentials contributed by different cell types within the retina, and the stimulus conditions can elicit stronger response from certain components.

<span class="mw-page-title-main">Strombidae</span> Family of molluscs

Strombidae, commonly known as the true conchs, is a taxonomic family of medium-sized to very large sea snails in the superfamily Stromboidea, and the Epifamily Neostromboidae. The term true conchs, being a common name, does not have an exact meaning. It may generally refer to any of the Strombidae but sometimes is used more specifically to include only Strombus and Lambis. The family currently includes 26 extant, and 10 extinct genera.

Aliger gigas, originally known as Strombus gigas or more recently as Lobatus gigas, commonly known as the queen conch, is a species of large sea snail, a marine gastropod mollusc in the family of true conches, the Strombidae. This species is one of the largest molluscs native to the Caribbean Sea, and tropical northwestern Atlantic, from Bermuda to Brazil, reaching up to 35.2 centimetres (13.9 in) in shell length. A. gigas is closely related to the goliath conch, Lobatus goliath, a species endemic to Brazil, as well as the rooster conch, Aliger gallus.

A simple eye refers to a form of eye or an optical arrangement composed of a single lens and without an elaborate retina such as occurs in most vertebrates. In this sense "simple eye" is distinct from a multi-lensed "compound eye", and is not necessarily at all simple in the usual sense of the word.

Strombus is a genus of medium to large sea snails, marine gastropod molluscs in the family Strombidae, which comprises the true conchs and their immediate relatives. The genus Strombus was named by Swedish Naturalist Carl Linnaeus in 1758. Around 50 living species were recognized, which vary in size from fairly small to very large. Six species live in the greater Caribbean region, including the queen conch, Strombus gigas, and the West Indian fighting conch, Strombus pugilis. However, since 2006, many species have been assigned to discrete genera. These new genera are, however, not yet found in most textbooks and collector's guides.

Cephalopods, as active marine predators, possess sensory organs specialized for use in aquatic conditions. They have a camera-type eye which consists of an iris, a circular lens, vitreous cavity, pigment cells, and photoreceptor cells that translate light from the light-sensitive retina into nerve signals which travel along the optic nerve to the brain. For the past 140 years, the camera-type cephalopod eye has been compared with the vertebrate eye as an example of convergent evolution, where both types of organisms have independently evolved the camera-eye trait and both share similar functionality. Contention exists on whether this is truly convergent evolution or parallel evolution. Unlike the vertebrate camera eye, the cephalopods' form as invaginations of the body surface, and consequently the cornea lies over the top of the eye as opposed to being a structural part of the eye. Unlike the vertebrate eye, a cephalopod eye is focused through movement, much like the lens of a camera or telescope, rather than changing shape as the lens in the human eye does. The eye is approximately spherical, as is the lens, which is fully internal.

Strombus pugilis, common names the fighting conch and the West Indian fighting conch, is a species of medium to large sea snail, a marine gastropod mollusk in the family Strombidae, the true conchs.

Laevistrombus canarium is a species of edible sea snail, a marine gastropod mollusc in the family Strombidae. Known from illustrations in books dating from the late 17th century, L. canarium is an Indo-Pacific species occurring from India and Sri Lanka to Melanesia, Australia and southern Japan. The shell of adult individuals is coloured from light yellowish-brown to golden to grey. It has a characteristic inflated body whorl, a flared, thick outer lip, and a shallow stromboid notch. The shell is valued as an ornament, and because it is heavy and compact, it is also often used as a sinker for fishing nets.

Lobatus raninus, common name the hawk-wing conch, is a species of medium to large sea snail, a marine gastropod mollusk in the family Strombidae, the true conchs.

Strombus alatus, the Florida fighting conch, is a species of medium-sized, warm-water sea snail, a marine gastropod mollusk in the family Strombidae, the true conchs. Its name derives two Latin words. Strombus means, in Latin, a snail with spiral shell, which derives from the Greek στρόμβος, meaning anything turned or spun around, like a top or, as in Aristotle's Historia Animalium, a sea snail. Alatus means, in Latin, "winged".

Aliger gallus, previously known as Strombus gallus, common name the rooster conch or rooster-tail conch, is a species of medium-sized sea snail, a marine gastropod mollusk in the family Strombidae, the true conchs.

Labiostrombus epidromis, common name the swan conch, is a species of sea snail, a marine gastropod mollusk in the family Strombidae, the true conchs.

Canarium fusiforme is a species of sea snail, a marine gastropod mollusk in the family Strombidae, the true conchs.

Canarium scalariforme is a species of sea snail, a marine gastropod mollusk in the family Strombidae, the true conchs.

Canarium labiatum, common name the Samar Conch, is a species of sea snail, a marine gastropod mollusk in the family Strombidae, the true conchs.

Canarium mutabile, common name the variable stromb, is a species of sea snail, a marine gastropod mollusk in the family Strombidae, the true conchs.

Strombus gracilior, common names the Eastern Pacific fighting conch, or the Panama fighting conch, is a species of medium to large sea snail, a marine gastropod mollusk in the family Strombidae, the true conchs.

Titanostrombus galeatus, commonly known as the Eastern Pacific giant conch, is a species of large sea snail, a marine gastropod mollusk in the family Strombidae, the true conchs and their allies.

References

↑ Rosenberg, G. (2011). Conomurex luhuanus (Linnaeus, 1758). Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=565370 on 2011-03-25
1 2 3 4 Catterall, C. P.; Poiner, I. R. (1983-12-01). "Age-and sex-dependent patterns of aggregation in the tropical gastropod Strombus luhuanus". Marine Biology. 77 (2): 171–182. doi:10.1007/BF00396315. ISSN 1432-1793.
1 2 Poutiers, J. M. (1998). Gastropods in: FAO Species Identification Guide for Fishery Purposes: The living marine resources of the Western Central Pacific Volume 1. Seaweeds, corals, bivalves and gastropods. Rome, FAO. page 475.
1 2 3 4 5 Simone, L. R. L. (2005). "Comparative morphological study of representatives of the three families of Stromboidea and the Xenophoroidea (Mollusca, Caenogastropoda), with an assessment of their phylogeny" (PDF). Arquivos de Zoologia. São Paulo, Brazil: Museu de Zoologia da Universidade de São Paulo. 37 (2): 141–267. doi: 10.11606/issn.2176-7793.v37i2p141-267 . ISSN 0066-7870. Archived from the original (PDF) on 2012-03-05.
1 2 3 Latiolais, J. M.; Taylor, M. S.; Roy, K.; Hellberg, M. E. (2006). "A molecular phylogenetic analysis of strombid gastropod morphological diversity" (PDF). Molecular Phylogenetics and Evolution . 41: 436–444. doi:10.1016/j.ympev.2006.05.027. PMID 16839783.
1 2 Kohn, Alan J.; Waters, Virginia (April 1966). "Escape responses of three herbivorous gastropods to the predatory gastropod Conus textile". Animal Behaviour. 14 (2–3): 340–345. doi:10.1016/s0003-3472(66)80094-5. ISSN 0003-3472.
1 2 Berg, Carl J. (1974). "A Comparative Ethological Study of Strombid Gastropods". Behaviour. 51 (3–4): 274–321. doi:10.1163/156853974x00219. ISSN 0005-7959.
↑ Hughes, HelenP.I. (August 1976). "Structure and regeneration of the eyes of strombid gastropods". Cell and Tissue Research. 171 (2): 259–71. doi:10.1007/bf00219410. ISSN 0302-766X. PMID 975213.
1 2 3 Gillary, Howard L.; Gillary, Elsa Winter (January 1979). "Ultrastructural features of the retina and optic nerve ofStrombus luhuanus, a marine gastropod". Journal of Morphology. 159 (1): 89–115. doi:10.1002/jmor.1051590108. ISSN 0362-2525.
↑ Seyer, Jan-Olof; Nilsson, Dan-E; Warrant, Eric J (1998). "Spatial Vision in the Prosobranch Gastropod Ampularia sp". The Journal of Experimental Biology. 201: 1673–1679.
↑ Chase, Ronald (2002). Behavior and its Neural Control in Gastropod Molluscs. New York, NY: Oxford University Press, Inc.
1 2 Gillary, Howard (1973). "Light-evoked electrical potentials from the eye and optic nerve of Strombus: Response waveform and spectral sensitivity". Journal of Experimental Biology. 60: 383–396.
↑ Gillary, Howard (1977). "Electric potentials from the eye and optic nerve of Strombus: Effects of electrical stimulation of the optic nerve". Journal of Experimental Biology. 66: 159–171.
↑ Seyer, Jan-Olof (1994-03-01). "Structure and optics of the eye of the hawk-wing conch,Strombus raninus (L.)". Journal of Experimental Zoology. 268 (3): 200–207. doi:10.1002/jez.1402680304. ISSN 0022-104X.
↑ Field, Laurence H (1977). "An experimental analysis of the escape response of the gastropod Strombus maculatus". Pacific Science. 31: 1–11.
1 2 Gillary, Howard (1983). "Electric Potentials from the Regenerating Eye of Strombus". Journal of Experimental Biology. 107: 293–310.
↑ Eakin, Richard M.; Ferlatte, Millie Miller (April 1973). "Studies on eye regeneration in a snail,Helix aspersa". Journal of Experimental Zoology. 184 (1): 81–95. doi:10.1002/jez.1401840107. ISSN 0022-104X. PMID 4695812.

Walls, J.G. (1980). Conchs, tibias and harps. A survey of the molluscan families Strombidae and Harpidae. T.F.H. Publications Ltd, Hong Kong

External links

Photos of Conomurex luhuanus on Sealife Collection

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[WoRMS-1] Rosenberg, G. (2011). Conomurex luhuanus (Linnaeus, 1758). Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=565370 on 2011-03-25

[:0-2] 1 2 3 4 Catterall, C. P.; Poiner, I. R. (1983-12-01). "Age-and sex-dependent patterns of aggregation in the tropical gastropod Strombus luhuanus". Marine Biology. 77 (2): 171–182. doi:10.1007/BF00396315. ISSN 1432-1793.

[Poutiers-3] 1 2 Poutiers, J. M. (1998). Gastropods in: FAO Species Identification Guide for Fishery Purposes: The living marine resources of the Western Central Pacific Volume 1. Seaweeds, corals, bivalves and gastropods. Rome, FAO. page 475.

[Simone2005-4] 1 2 3 4 5 Simone, L. R. L. (2005). "Comparative morphological study of representatives of the three families of Stromboidea and the Xenophoroidea (Mollusca, Caenogastropoda), with an assessment of their phylogeny" (PDF). Arquivos de Zoologia. São Paulo, Brazil: Museu de Zoologia da Universidade de São Paulo. 37 (2): 141–267. doi: 10.11606/issn.2176-7793.v37i2p141-267 . ISSN 0066-7870. Archived from the original (PDF) on 2012-03-05.

[Latiolais2006-5] 1 2 3 Latiolais, J. M.; Taylor, M. S.; Roy, K.; Hellberg, M. E. (2006). "A molecular phylogenetic analysis of strombid gastropod morphological diversity" (PDF). Molecular Phylogenetics and Evolution . 41: 436–444. doi:10.1016/j.ympev.2006.05.027. PMID 16839783.

[:1-6] 1 2 Kohn, Alan J.; Waters, Virginia (April 1966). "Escape responses of three herbivorous gastropods to the predatory gastropod Conus textile". Animal Behaviour. 14 (2–3): 340–345. doi:10.1016/s0003-3472(66)80094-5. ISSN 0003-3472.

[:5-7] 1 2 Berg, Carl J. (1974). "A Comparative Ethological Study of Strombid Gastropods". Behaviour. 51 (3–4): 274–321. doi:10.1163/156853974x00219. ISSN 0005-7959.

[8] Hughes, HelenP.I. (August 1976). "Structure and regeneration of the eyes of strombid gastropods". Cell and Tissue Research. 171 (2): 259–71. doi:10.1007/bf00219410. ISSN 0302-766X. PMID 975213.

[:2-9] 1 2 3 Gillary, Howard L.; Gillary, Elsa Winter (January 1979). "Ultrastructural features of the retina and optic nerve ofStrombus luhuanus, a marine gastropod". Journal of Morphology. 159 (1): 89–115. doi:10.1002/jmor.1051590108. ISSN 0362-2525.

[10] Seyer, Jan-Olof; Nilsson, Dan-E; Warrant, Eric J (1998). "Spatial Vision in the Prosobranch Gastropod Ampularia sp". The Journal of Experimental Biology. 201: 1673–1679.

[11] Chase, Ronald (2002). Behavior and its Neural Control in Gastropod Molluscs. New York, NY: Oxford University Press, Inc.

[:3-12] 1 2 Gillary, Howard (1973). "Light-evoked electrical potentials from the eye and optic nerve of Strombus: Response waveform and spectral sensitivity". Journal of Experimental Biology. 60: 383–396.

[13] Gillary, Howard (1977). "Electric potentials from the eye and optic nerve of Strombus: Effects of electrical stimulation of the optic nerve". Journal of Experimental Biology. 66: 159–171.

[14] Seyer, Jan-Olof (1994-03-01). "Structure and optics of the eye of the hawk-wing conch,Strombus raninus (L.)". Journal of Experimental Zoology. 268 (3): 200–207. doi:10.1002/jez.1402680304. ISSN 0022-104X.

[15] Field, Laurence H (1977). "An experimental analysis of the escape response of the gastropod Strombus maculatus". Pacific Science. 31: 1–11.

[:4-16] 1 2 Gillary, Howard (1983). "Electric Potentials from the Regenerating Eye of Strombus". Journal of Experimental Biology. 107: 293–310.

[17] Eakin, Richard M.; Ferlatte, Millie Miller (April 1973). "Studies on eye regeneration in a snail,Helix aspersa". Journal of Experimental Zoology. 184 (1): 81–95. doi:10.1002/jez.1401840107. ISSN 0022-104X. PMID 4695812.

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