CANARIUM SHELLS OF THE INDO-PACIFIC
Laevistrombus canarium
Laevistrombus canariums (commonly known as the dog conch or by its better-known synonym, Strombus canarium) is a species of edible sea snail, a marine gastropod mollusk in the family Strombidae, the true conches
L. canarium is an Indo-Pacific species. They are found from India and Sri Lanka to Melanesia, Australia and to the shores of southern Japan
The dog conch lives on muddy sand bottoms among algae and seagrass beds on insular and continental shores. It usually prefers major islands and continental coasts rather than the shores of small islands, although this is not an absolute rule. Laevistrombus canarium prefers areas of mixed seagrasses (with a predominance of Halophila), and also prefers sediment with high levels of organic matter. This conch avoids environments with a high density of Enhalus acoroides, a large seagrass native to coastal waters of the Indo-Pacific. The dog conch can be found in littoral and sublittoral zones, from shallow water to a depth of 55 m (180 ft). They are normally found in large colonies, and are usually abundant wherever it occurs
(REF: Poutiers, J. M. (1998). "Gastropods") (REF: Cob, Z. C.; Arshad, A.; Bujang, J. S.; Bakar, Y.; Simon, K. D.; Mazlan, A. G. (2012). "Habitat preference and usage of Strombus canarium Linnaeus, 1758 (Gastropoda: Strombidae) in Malaysian seagrass beds". Italian Journal of Zoology. 79 ) (REF: Cob, Z. C.; Arshad, A.; Idris, M. H.; Bujang, J. S.; Ghaffar, M. A. (2008). "Sexual polymorphism in a population of Strombus canarium Linnaeus, 1758 (Mollusca: Gastropoda) at Merambong Shoal, Malaysia")
The Laevistrombus canarium prefers muddy, sandy bottoms; where they graze on algae and detritus. It is gonochoristic and sexually dimorphic, depending on internal fertilization for spawning. Larvae of this species spend several days as plankton, undergoing a series of transformations until they reach complete metamorphosis.
The Laevistrombus canarium maximum life span is 2 to 2 1/2 years. Predators of this snail include carnivorous gastropods such as cone snails and volutes. It is also a prey species for vertebrates including macaques and humans, who consume the soft parts in a wide variety of dishes.
Metamorphosis is a biological process by which an animal physically develops including birth transformation or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some insects, fish, amphibians, mollusks, crustaceans, cnidarians, echinoderms, and tunicates undergo metamorphosis, which is often accompanied by a change of nutrition source or behavior. Animals can be divided into species that undergo complete metamorphosis ("holometaboly"), incomplete metamorphosis ("hemimetaboly"), or no metamorphosis ("ametaboly").
(REF: "metamorphosis biology Britannica") (REF: "Which animals undergo incomplete metamorphosis?Easierwithpractice.com") (REF: Truman, James W. (2019-12-02). "The Evolution of Insect Metamorphosis". Current Biology. 29)
Generally organisms with a larval stage undergo metamorphosis, and during metamorphosis the organism loses larval characteristics.
detritus is dead particulate organic material, as distinguished from dissolved organic material. Detritus typically includes the bodies or fragments of bodies of dead organisms, and fecal material. Detritus typically hosts communities of microorganisms that colonize and decompose (i.e. remineralize) it. In terrestrial ecosystems it is present as leaf litter and other organic matter that is intermixed with soil, which is denominated "soil organic matter". The detritus of aquatic ecosystems is organic substances that is suspended in the water and accumulates in depositions on the floor of the body of water; when this floor is a seabed, such a deposition is described as marine snow.
In biology,gonochorism is a sexual system where there are only two sexes and each individual organism is either male or female.[1] The term gonochorism is usually applied in animal species, the vast majority of which are gonochoric.
(REF: Kliman RM (2016). "Hermaphrodites". In Schärer L, Ramm S (eds.). Encyclopedia of Evolutionary Biology) (REF: Holub AM, Shackelford TK (2020). "Gonochorism". In Vonk J, Shackelford TK (eds.). Encyclopedia of Animal Cognition and Behavior)
Laevistrombus canarium has a heavy shell with a rounded outline. The average shell length of adult specimens ranges from 1 to 3 inches. The outer surface of the shell is almost completely smooth, except for barely visible spiral lines and occasional varices on the spire. Unlike species in the genus Strombus, the stromboid notch on the outer lip is inconspicuous. When a normal adult dextral shell of this species is viewed ventrally (with the anterior end pointing downwards), the stromboid notch can be observed to the right of the siphonal canal as a shallow, secondary anterior indentation in the lip. The siphonal canal itself is straight, short, and ample; the columella is smooth, without any folds. Adult specimens have a moderately flared, posteriorly protruding outer lip, which is considerably thickened and completely devoid of marginal spikes. The body whorl is roundly swollen at the shoulder, with a few anterior spiral grooves. The shell has a medium-to-high cone-shaped spire, with at least five delicately furrowed whorls.
Shell color is variable, from golden yellow to light yellowish-brown to grey. The underside of the shell is rarely dark; more frequently it is paler than the top, or totally white. In all cases, the shell aperture is white. Mature specimens sometimes have a metallic-grey or golden-brown gloss on the margin of the outer lip and the callus. A zigzag network of darker lines is sometimes present on the outside of the shell. The periostracum, a layer of protein (conchiolin) that is the outermost part of the shell surface, is yellowish-brown. It is usually thick, reticulated (net-like), and fimbriated (fringed) over the suture. The corneous operculum is dark brown, and its shape is fairly typical of the family Strombidae: a slightly bent sickle, with seven or eight weak lateral serrations.
(REF: Poutiers, J. M. (1998). "Gastropods") (REF:Cob, Z. C.; Arshad, A.; Bujang, J. S.; Ghaffar, M. A. (2009). "Species description and distribution of Strombus (Mollusca: Strombidae) in Johor Straits and its surrounding areas" ) (REF: Man In 'T Veld, L. A.; De Turck, K. (1998). "Contributions to the knowledge of Strombacea. A revision of the subgenus Laevistrombus Kira, 1955 including the description of a new species from the New Hebrides")
The external anatomy of the soft parts of this species is similar to that of other strombid snails. The animal has an elongated snout, thin eyestalks with well-developed eyes and sensory tentacles, and a narrow, strong foot with a sickle-shaped operculum. The dog conch exhibits behaviours common among the Strombidae, including burrowing and a characteristic leaping form of locomotion. The former behaviour, however, involves movement sequences unique to this species.
An eyestalk (sometimes spelled eye stalk and also known as an ommatophore) is a protrusion that extends an eye away from the body, giving the eye a better field of view.
(REF: "Slug and Snail Anatomy". All About Slugs )
Females of Laevistrombus canariums are generally larger (both shell and soft parts) than males, which is also the case in other strombid gastropods such as the spider conch (Harpago chiragra) and queen conch (Lobatus gigas). The external anatomy of the soft parts of this species is similar to that of the other members of the family; the animal has a long, extensible snout and thin eyestalks (also known as ommatophores), with well-developed lens eyes at the tips. Each eyestalk has a small sensory tentacle branching off near the end. The large foot of the animal is narrow and strong, able to perform the leaping form of locomotion that is also found in other species of the Strombidae.
(REF: Cob, Z. C.; Arshad, A.; Ghaffar, M. A.; Bujang, J. S.; Muda, W. L. W. (2009). "Development and growth of larvae of the dog conch, Strombus canarium (Mollusca: Gastropoda), in the laboratory")
Compared to most other gastropods, Laevistrombus canarium has a means of locomotion that is common only among the Strombidae. This series of movements was originally described by American zoologist George Howard Parker in 1922. The animal first fixes the posterior end of the foot by thrusting the point of its sickle-shaped operculum into the substrate. Then, it extends its foot forward, lifting the shell and throws it ahead in a motion that has been described as "leaping".
(REF:Cob, Z. C.; Arshad, A.; Ghaffar, M. A.; Bujang, J. S.; Muda, W. L. W. (2009). "Development and growth of larvae of the dog conch, Strombus canarium (Mollusca: Gastropoda), in the laboratory" ) (REF: Parker, G. H. (1922). "The leaping of the stromb (Strombus gigas Linn.)". Journal of Experimental Zoology. 36 )
Burrowing behaviour, in which an individual sinks itself entirely (or partially) into the substrate, is frequent among strombid gastropods. The burrowing behaviour of Laevistrombus canarium consists of a series of movements characteristic of the species. There are three consecutive movements: first is probing, where the animal pushes the anterior portion of the foot into the substrate to gain a hold; next is shovelling, where it pushes the substrate with its long, extensible proboscis. Retraction is the final movement, where it moves the shell along an anterior-posterior axis to settle the substrate around it. Once burrowed, part of the dorsal shell is usually still visible (although the ventral surface and the animal's soft parts are buried)
(REF: Savazzi, E. (1989). "New observations on burrowing in strombid gastropods")
The escape response in gastropods—the perception of stimuli (for example, the presence of a predator nearby) and a subsequent escape motion—is a frequent target of behavioral studies. In gastropods, the perception of environmental chemical stimuli originating, for example, from food or other organisms is possibly mediated by sensory organs such as the osphradium. In the case of L. canarium, the perception of a predator can occur through chemoreception or vision (a well-developed sense in strombid gastropods). The presence of a predator can significantly alter the movement pattern of L. canarium, inducing an increase in the frequency of leaps.
(REF:Kohn, A. J.; Waters. V. (1966). "Escape responses of three herbivorous gastropods to the predatory gastropod Conus textile". Animal Behaviour. 14 ) (REF: Brusca, R. C.; Brusca, G. J. (2003). "Phylum Mollusca". Invertebrates. Sinauer Associates.) (REF: Beesley, P. L.; Ross, G. J. B.; Wells, A. (1998). Mollusca: The Southern Synthesis. Fauna of Australia: Part B.)
Laevistrombus canarium are gonochoristic, which means that each individual animal is distinctly male or female. The breeding season starts in late November and continues until early March. After internal fertilization the female produces and spawns a long, gelatinous tubular structure containing multiple eggs. This structure then coils itself and compacts, forming a creamy-white egg mass. Each egg mass may contain 50,000–70,000 eggs; the females usually lay them on seagrass, where they remain attached. In about 110–130 hours the embryo of L. canarium grows from a single cell to a veliger (a larval form common to marine and fresh-water gastropod and bivalve mollusks) and then hatches. The hatching process takes 12–15 hours. After hatching, the larvae can be assigned to four distinct developmental stages throughout their short planktonic lives (based on morphological features and other characteristics). Usually, larvae up to 3 days old are stage I veligers; 4– to 8-day-old larvae are stage II; 9– to 16-day-old larvae are stage III, and larvae from 17 days to metamorphosis are stage IV. L. canarium larvae develop faster compared to other species in the same family, including the West Indian fighting conch (Strombus pugilis) and the milk conch (Lobatus costatus). Larval development may be highly influenced by environmental conditions, such as temperature and the quality and availability of food. Metamorphosis in L. canarium can be recognized by loss of the larval velar lobes and the development of the typical leaping motion of juvenile true conches.
(REF: Cob, Z. C.; Arshad, A.; Ghaffar, M. A.; Bujang, J. S.; Muda, W. L. W. (2009). "Development and growth of larvae of the dog conch, Strombus canarium (Mollusca: Gastropoda), in the laboratory") (REF: Brusca, R. C.; Brusca, G. J. (2003). Invertebrates (2nd ed.). Sinauer Associates) (REF: Cob, Z. C.; Arshad, A.; Idris, M. H.; Bujang, J. S.; Ghaffar, M. A. (2008). "Sexual polymorphism in a population of Strombus canarium Linnaeus, 1758 (Mollusca: Gastropoda) at Merambong Shoal, Malaysia")
Scientific classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Subclass: Caenogastropoda
Order: Littorinimorpha
Family: Strombidae
Genus: Laevistrombus
Species: L. canarium
Binomial name: Laevistrombus canarium
(Linnaeus, 1758)
U1-9
One quarter pound of Laevistrombus (Canarium shells), shells measuring between 2 and 2.5 inches. ...... .85