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Conus geographusgeography cone snail

By Miranda Hall

Geographic Range

The geographic cone snail, Conus geographus, is indigenous to the tropical and subtropical Indo-Pacific regions, found specifically along the northern shores of Australia, ranging from the west coast (Brisbane, Queensland), central (Darwin, Northern Territory), and east coast (Exmouth, Western Australia). Rare sightings (and recorded fatalities) have also been reported in New Caledonia. (Chadwick, 2011; Estival, 1981; Walls, 1978)

Habitat

Geographic cone snails are most commonly found in the sublittoral epipelagic zone. Their surrounding habitat includes living or fragmented coral reefs, and sandy regions within tidal zones. They are less commonly found in deeper waters. (Chadwick, 2011; Estival, 1981; Lim and Wee, 1992)

  • Range depth
    0 to 200 m
    0.00 to 656.17 ft

Physical Description

A calcareous, smooth shell covers the mollusk’s soft body. The shell spire is obconical (having a length of less than or equal to 10% of the entire structure) featuring coronation (small bumps) at and above the shoulder along the edges of the larger whorls. The spire is concave with smooth sutures and a prominent point at the protoconch apex. The body whorl terminates in an elongated aperture that has a width of about 1/3 of the overall shell width. The outer shell’s coloration ranges from ground colors of white, cream, or rose pink overlain with brown or red mottled patterns arranged in horizontal spirals along the body whorl. The shell is covered with a thin yellowish layer of protein-based material called the periostracum, forming tufts on the spire, on the spiral rows, and along the body whorl, following the sculpture of the shell. This protein covering gives the cone a roughened appearance.

The most obvious features of the geographic cone snail are the foot, which extends from the aperture; two small eyes borne on eyestalks, and two features associated with their feeding habits: the proboscis, an extendable protrusion in the oral region that expands to swallow its prey, and the siphon, an extension of the mantle tissue, used for chemoreception of its prey. The cone snail uses a elaborately scuplted, hollow radular tooth (housed in the proboscis) as a harpoon to incapacitate its prey. Venom glands produce deadly toxins and digestive enzymes, and these are injected into the snail’s prey through the radular tooth. (Walls, 1978)

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    13.3 to 62 g
    0.47 to 2.19 oz
  • Average mass
    38.8 g
    1.37 oz
  • Range length
    70 to 150 mm
    2.76 to 5.91 in

Development

Very little is known of the cone shell’s natural history from neoteny to adulthood. After the mating ritual, clusters of egg sacs (about 40 eggs per sac) are extruded and attached on a suitable hard surface. The eggs incubate within their capsule for 10 to 15 days before maturing into the larval stage. After twenty days, the transparent shells and bodies are visible, and they break from their capsules and drift in the plankton as meroplanktonic veliger larvae (a temporary zooplanktonic stage of the lifecycle). The larval diet is unknown, but assumed to be smaller plankton. Only a low percentage of cone snail larvae survive to metamorphose into benthic juveniles, and even fewer survive to reach adulthood. Planktonic survival rate is affected by weather and oceanographic factors such as water temperature, salinity, and ocean currents, as well as abundance of secondary consumers in the water column. (Cruz, et al., 1978; Estival, 1981)

Reproduction

Published observations on reproductive behavior were made in aquaria, and direct observations on ritual courtships or competition for a mate in the wild is lacking. Some researchers hypothesize that male cone snails may exhibit territoriality to ensure access to potential mates.

During copulation, the male mounts the female using its foot. It inserts about 2/3 of a ribbon-like organ called the verge (analogous to a penis) into the female’s opening near the anal notch. This position is maintained for at least 15 minutes before the male retracts its verge. Two to three days later, the female lays several capsules eggs on a hard surface. No information is available as to whether mating occurs singly or at multiple times across the lifespan. (Cruz, et al., 1978; Estival, 1981)

Sexual maturity may occur between 6 to 12 months. After mating, the female lays her egg capsules on a smooth, hard surface, where they develop into larvae in twenty days. (Cruz, et al., 1978; Estival, 1981)

  • Breeding interval
    Geographic cone snails breed once a year.
  • Breeding season
    Between April and September when the waters are warm.
  • Range number of offspring
    1000 to 5000
  • Average number of offspring
    2500
  • Range gestation period
    2 to 3 days
  • Average gestation period
    3 days
  • Range time to independence
    15 to 25 days
  • Range age at sexual or reproductive maturity (female)
    6 to 12 months
  • Range age at sexual or reproductive maturity (male)
    6 to 12 months

There is no further investment in parental care after eggs are laid, as is the case for most marine invertebrates. (Cruz, et al., 1978)

  • Parental Investment
  • no parental involvement
  • precocial
  • pre-fertilization

Lifespan/Longevity

There is no recorded data of any longevity in the wild or captivity.

Behavior

The geographic cone is inactive during the day, burying itself in the sand to camouflage itself for both protection and hunting. At night the snails are active to hunt food. Some researchers hypothesize that male cone snails may exhibit territoriality in their hunting grounds. (Cruz, et al., 1978; Johnson and Stablum, 1971)

Home Range

There is no recorded data of any home range information. (Johnson and Stablum, 1971)

Communication and Perception

The three main methods of perception used are visual (eyes to detect light), tactile (using its foot) and chemoreception (detecting dissolved chemicals in the water). It is likely that potential mates are detected using all three of these senses. (Cruz, et al., 1978; Johnson and Stablum, 1971)

Food Habits

Conus geographus is nocturnal, hunting at night when its fish prey are the least active or at rest. They crawl on top of the substrate, or crawl while buried beneath the sand. Diet consists of small (30 to 50 mm) and medium (100 to 130 mm) sized fishes that fit into its rostrum (mouth). Larger snails (80 to 87 mm) are able to capture and ingest larger fishes between 130 and 140 mm in length. (Cruz, et al., 1978; Johnson and Stablum, 1971)

Observations show that snails hunt with two methods used by other Conus species: the hook-and-line method and the net-hunting method. In the hook-and-line method, the snail slowly approaches its prey, waving its proboscis like a lure to attract the fish before stinging the fish with its radula. The fish jerks violently for a few moments and is injected with a paralyzing excitotoxin venom that stiffens the fish, allowing the cone snail to swallow it whole. Several hours or days later, the snail regurgitates the fish’s bones. Another method is net-hunting, wherein a fish is engulfed in one mouthful before being harpooned with the radular tooth. (Chadwick, 2011; Cruz, et al., 1978; Johnson and Stablum, 1971)

  • Animal Foods
  • fish

Predation

Predators during its larval period include nektonic fishes and filer-feeding invertebrates that consume zooplankton. As an adult, the only enemies the geographic cone snail may fear are mollusk-eating vertebrates such as sea turtles and rays, and human shell collectors. The radular tooth also serves as a defense mechanism against potential predators. (Johnson and Stablum, 1971)

  • Anti-predator Adaptations
  • cryptic
  • Known Predators
    • large fish
    • humans

Ecosystem Roles

The geographic cone snail is a piscivore, thus it influences the ecosystem dynamics of coral reef populations of small fish species. (Chadwick, 2011; Cruz, et al., 1978; Johnson and Stablum, 1971)

Economic Importance for Humans: Positive

Conantokins ("sleeper peptides") from the geographic cone snail are a complex mix of short-chain peptides that affect a number of neural receptors in fish and mammals. The potential therapeutic and economic benefits from conantokins have great potential. Conantokins are antagonists to the nicotinic aceytlcholine receptors (the means by which the cone snails paralyze their prey) and N-Methyl-D-aspartic acid (NMDA) receptors, which (in humans) are involved with pain reception, drug and alcohol withdrawal symptoms, memory, and learning. Con-G, one of the conantokins from the geographic cone snail, is a potent analgesic, particularly for nociceptive pain (pain that warns the body of tissue injury or other serious damage). Con-G specifically acts on the NR2B NMDA receptor subtype, which means it is more selective than morphine for treating chronic neuropathic pain found in patients suffering from cancer, arthritis, shingles, diabetes, and AIDS. Therefore, smaller doses can be used, and Con-G does not seem to be addictive or to have side effects in the therapeutic dose range, unlike morphine. In addition, since NMDA receptors are involved with memory, conantokins can potentially be used in treating Alzheimer's and Parkinson's diseases, and possibly used as anti-convulsants in epilepsy or as a means of alleviating drug-induced withdrawal symptoms. In addition, Con-G has been found to act as a neuroprotective agent in brain ischemia from strokes. (Jimenez, 2009; Livett, et al., 2004; Sprackland, 2005)

Economic Importance for Humans: Negative

The conantokins in one sting can kill 15 people. Symptoms include an excruciating pain at the penetrated area, much worse than a bee’s sting. As the pain fades, numbness soon sets in, followed by dizziness, slurred speech, and respiratory paralysis. Death can follow within half an hour afterward, but this is rare. Presently, there is no known anti-venom; applied pressure on the wound, immobilization and artificial respiration (mouth-to-mouth resuscitation) are the only recommended treatments for the victim. (Chadwick, 2011)

  • Negative Impacts
  • injures humans

Conservation Status

This species is not listed as vulnerable, threatened, or endangered.

Contributors

Miranda Hall (author), San Diego Mesa College, Paul Detwiler (editor), San Diego Mesa College, Renee Mulcrone (editor), Special Projects.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

World Map

benthic

Referring to an animal that lives on or near the bottom of a body of water. Also an aquatic biome consisting of the ocean bottom below the pelagic and coastal zones. Bottom habitats in the very deepest oceans (below 9000 m) are sometimes referred to as the abyssal zone. see also oceanic vent.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

drug

a substance used for the diagnosis, cure, mitigation, treatment, or prevention of disease

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

fertilization

union of egg and spermatozoan

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

indeterminate growth

Animals with indeterminate growth continue to grow throughout their lives.

internal fertilization

fertilization takes place within the female's body

intertidal or littoral

the area of shoreline influenced mainly by the tides, between the highest and lowest reaches of the tide. An aquatic habitat.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

piscivore

an animal that mainly eats fish

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

tactile

uses touch to communicate

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

venomous

an animal which has an organ capable of injecting a poisonous substance into a wound (for example, scorpions, jellyfish, and rattlesnakes).

visual

uses sight to communicate

young precocial

young are relatively well-developed when born

References

Chadwick, A. 2011. "The Cone Snail" (On-line). Accessed June 21, 2011 at http://www.theconesnail.com/.

Cruz, L., G. Corpuz, B. Olivera. 1978. Mating, spawning, development and feeding habits of Conus geographus in captivity. The Nautilus, 92 (4): 150-153.

Estival, J. 1981. Cone Shells of New Caledonia and Vanuatu. Paris, France: Editions Du Cagou.

Jimenez, E. 2009. Conantokins: from “sleeper” activity to drug development. Philippine Science Letters, 2 (1): 60-65. Accessed June 21, 2011 at http://www.philsciletters.org/pdf/200921.pdf.

Johnson, C., W. Stablum. 1971. Observations on the feeding behavior of Conus geographus (Gastropoda:Toxoglossa). Pacific Science, 25 (1): 109-111. Accessed June 21, 2011 at http://scholarspace.manoa.hawaii.edu/retrieve/24289/license.txt.

Lim, C., V. Wee. 1992. Southeast Asia Conus: a Seashells Book. Singapore: Seaconus Private Limited.

Livett, B., K. Gayler, Z. Khalil. 2004. Drugs from the sea: conopeptides as potential therapeutics. Current Medicinal Chemistry, 11 (13): 1715-1723. Accessed June 21, 2011 at http://grimwade.biochem.unimelb.edu.au/cone/publications/Livett_CMC3.pdf.

Marsh, J. 1964. Cone Shells of the World. Milton: Jacaranda Press.

Sprackland, R. 2005. Toxic treasure. Natural History, October: 40-45. Accessed June 21, 2011 at http://eebweb.arizona.edu/courses/Ecol437/Sprackland-NatHist_Toxins_Oct2005.pdf.

Walls, J. 1978. Cone Shells: A Synopsis of the Living Conidae. Neptune City, N.J: T.F.H Publications, Inc.

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