Table of Contents Coral Reef Cart Collection



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Mollusks: Gastropods




Cone Snail




Specimens

cone snail shell
general inforamtion

Classification

Distribution


    • Generally found in temperate to tropical oceans. Most species found in Indo-Pacific. Also found in Australia, Japan, west Africa, California, Florida-Caribbean and Pacific-Panama area.

Habitat


    • Most cones are found in shallow reef areas hiding in the sand, under coral shelves or in piles of rocky rubble. Some live among mangroves.

Appearance and Behavior


    • The size of cone snails varies from 1.3 cm to 21.6 cm. Cone snails have heavy, smooth shells that are narrow at one end and wide at the other. All have spires of varying heights at the wide end. The shell’s aperture is long and narrow and does not have an operculum. The foot is strong and may be colorful. The siphon may also be colorful. The head has two tentacles, each with an eye halfway down. Shell colors and patterns vary. Most have patterns of black, brown, orange or yellow over a light background.

    • This snail’s unique feature is a “harpoon” that is a single, specialized radula tooth equipped with a spear-like barbed tip. The cone snail detects the presence of its prey using chemosensors in its siphon and, when close enough, extends its proboscis (which also acts as a lure) and fires its hollow harpoon-like tooth containing venom into the prey. The harpoons are stored in the radula sac and moved into the proboscis one at a time as needed. They then become attached to a salivary gland, which has been modified to produce venom before the harpoon is fired. The barbed tooth has a groove through which the snail injects the neurotoxic peptide venom (conotoxin) into its victim. This immobilizes the prey and enables the cone snail to wind it into its mouth via an attached filament.

Diet


    • Cones are carnivorous. They are classified as fish eaters, mollusk eaters, or worm eaters. Most cones are nocturnal though some hunt at dusk and dawn. They may hide with only the siphon visible before striking their prey.

Reproduction and Development


    • Although not widely studied, most of these snails seem to have separate sexes. Fertilization is internal. Egg capsules are attached to substrate. Two types of hatchlings have been described: veligers (free swimming larvae) and veliconcha (basically baby snails).

Conservation Status


    • Prized for their shells, cone snails are in danger of being over-harvested by collectors. They are also collected for scientific studies on potential uses of the venoms for medicine. This could result in depleted populations. Some countries have put restrictions on their collection and sale. At present only four species are listed as Vulnerable by IUCN.

Remarks


    • Research on cone snail toxins is an active field and has resulted in a new, highly effective painkiller recently approved by the FDA that, unlike opium-derived medications, has a low risk of addiction and can be much more potent than morphine. Small cone snails pose little danger to humans beyond a beelike sting. However, large cone snails inject enough toxin to be deadly. About 30 human deaths have been attributed to cone snail envenomation.



To Notice

    • Notice how this beautiful shell gives no indication of the venom that might be within.

    • Using a photo or diagram, point out where the foot, siphon, and proboscis would be located.

    • Show a photo of a cone snail feeding.

    • Compare the cone snails’ use of a “harpoon” to inject venom to the venom delivery system of ray barbs and coral nematocysts.

Tiger Cowrie

Specimen

tiger cowrie shell Cypraea tigris (Cypraeidae)

General Information

Classification


    • Phylum Mollusca, Class Gastropoda

Distribution


    • Indo-Pacific, including Hawaii

Habitat


    • Rocky and coral areas

Appearance and Behavior


    • 10-15 cm in size. In cowries the spire (pointed end) of the shell is overgrown by the last whorl, resulting in a rounded domed shape.

    • The shell may be white or golden brown with scattered dark brown or black spots.

    • The shell-producing mantle tissue has two special folds that extend outside the shell. These mantle folds keep the shell clean and polished and prevent boring or encrusting organisms from causing damage to the shell surface.

    • The mantle is covered with frilly, branched projections called papillae. The functions of the papillae are not clear. They may provide camouflage for the animal by breaking up the snail’s outline or they may allow absorption of oxygen from the seawater. When disturbed, the mantle retracts, revealing the glossy shell.

    • Cowries, like other snails, have a well-developed head with eyes and tentacles, a mouth on a protractible proboscis (mouth tube), a broad muscular foot for crawling, and a soft body mass containing internal organs.

    • Cowries are most active at night and conceal themselves during the day.

Diet


    • Algae or encrusting invertebrates like sponges and bryozoans. It uses its file-like radula to scrape food from rock and reef.

Reproduction and Development


    • Sexes are separate and fertilization is internal. The female lays a cluster of white, parchment-like capsules containing the developing snail embryos. The female broods these capsules, protecting them by covering them with her foot, until the swimming larvae hatch and enter the plankton where they drift and develop.

Conservation status:


    • Most of the species are still relatively common, but a few are becoming rare.

Remarks


    • The glossy shells have been used for centuries as ornaments, money and religious symbols. Today they rank high with shell collectors.
To Notice

    • Notice the smoothness of the shell.

    • Locate where the foot and body mass would be.

    • Compare the appearance of this bare shell to a cowrie covered with a mantle (in a photo).

    • Compare this shell to the other mollusk shells on the cart.


Murex

Specimens

Pink-mouthed murex Murex erythrostomus

unidentified murex


GENERAL INFORMATION

Classification


    • Phylum Mollusca, Class Gastropoda

Distribution:


    • The Muricidae family is found worldwide. Most are tropical, but some inhabit colder water, such as the species known to decimate oyster beds. The U.S. Atlantic coast and Gulf of Mexico have numerous species.

Habitat


    • Most murex species live in the intertidal or shallow subtidal zone, among rocks and corals and on sandy mudflats.

Appearance and Behavior


    • Murex snails are noted for their spectacular, sometimes bizarre ornamentation, which most likely protects the animals from predation.

    • Much of what is known about the working of the gastropod radula has been learned from studies of this family of snails.

    • Typically a murex mounts its prey and works its way through its victim’s shell by alternately using its radula to mechanically scrape away the shell and then using secretions from an accessory boring organ to chemically soften the shell, making it more susceptible to mechanical wear from the radula.

Diet


    • Murex species are typically active carnivores, feeding on other snails, barnacles, oysters, mussels, chitons, and other invertebrates.

    • The cart species, the pink-mouthed murex, preys upon large clams in the extreme low-tide level.

Reproduction and Development


    • Sexes are separate and fertilization is internal. Most murex snails spend their larval stages within an egg capsule, ultimately emerging as tiny snails.

Conservation Status


    • Most species are plentiful, but a few that are especially desirable to collectors are increasingly scarce.

Remarks


    • Murex snails were used as a source of dye by the Phoenicians. The murex snails secrete a yellowish fluid which, when boiled and treated, makes a permanent purple dye. Wool and silk dyed with this Royal Tyrian purple brought very high prices. Many new towns were settled in the western Mediterranean by Phoenicians seeking fresh beds of the shells.

    • Greeks and Romans also made use of the dye. During Roman times only Senators and Emperors were allowed to wear purple cloth.

    • After the fall of the Roman Empire the dye was used by the Christian Church and gave rise to the official color of the Cardinals.

    • The dye is also used in the Jewish religion.


To Notice

    • Notice the spines covering the shell that discourage predators.

    • Note the small worms on the shell-- may have settled on the shell when alive or dead.



Triton’s Trumpet




Specimen

Triton’s Trumpet Charonia tritonis (Cymatiidae)
general information

Classification


    • Phylum Mollusca, Class Gastropoda

    • Its name refers to Triton, the ancient Mediterranean God of the Sea.

Distribution


    • Throughout the Indo-Pacific, in the Red Sea, along the tropical coast of Africa (Mozambique), and in southern Japan.

Habitat


    • In tropical waters to the depth of 3 – 40 m.

Appearance and Behavior


    • This is one of the largest and best known tropical gastropods. Like other snails, the Triton’s trumpet has a well-developed head with eyes and tentacles, a mouth on a protractible proboscis (mouth tube), a broad muscular foot for crawling, and a soft body mass containing the internal organs, which is protected by the shell. It may exceed 50 cm in length (almost 20 inches).

Diet


    • This species feeds on many different echinoderms, but most notably the crown of thorns sea star, which is a significant coral predator. After locating its prey, the trumpet snail immobilizes the sea star with an injection of paralytic salivary juices, then bores through the sea star’s mesh-like skeleton with sturdy radular teeth to reach the soft tissue inside.

Reproduction and Development


    • Sexes are separate in the trumpet snails and fertilization is internal. The female lays a cluster of white, club-shaped capsules containing the developing snail embryos. The young hatch from the capsules as swimming larvae and enter the plankton to drift in the open water.

Conservation Status


    • Because it is predatory on the crown of thorns, this species is protected by law in some countries, including Australia, Fiji, and the Seychelles.

Remarks


    • Traditional use includes chipping a small hole near the end of the spire and blowing into it as one would a trumpet.
To Notice

    • Using a drawing/photo of a Triton’s trumpet, point out where the eyes, mouth and foot would be located.

    • Show a photo of Triton’s trumpet consuming a crown of thorns sea star.

    • Compare to other gastropods on the cart such as the murex, cowrie, and cone snail..

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