Dicathais | |
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Dorsal view of a shell of Dicathais orbita | |
Apertural view showing the deep crenulations | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Mollusca |
Class: | Gastropoda |
Subclass: | Caenogastropoda |
Order: | Neogastropoda |
Family: | Muricidae |
Genus: | Dicathais Iredale, 1936 [1] |
Species: | D. orbita |
Binomial name | |
Dicathais orbita (Gmelin, 1791) | |
Synonyms [1] | |
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Dicathais is a genus of predatory sea snails, marine gastropod molluscs in the family Muricidae, the rock snails. This genus is monotypic; the only species in it is Dicathais orbita, common name the white rock shell or cart-rut shell, found round the coasts of Australia and New Zealand.
The white rock shell is large with a strong shell usually about 6 centimetres (2.4 in) long, but occasionally growing to twice this size. It shows great variation in its shell sculpture across its range. In eastern Australia there are seven to nine deeply indented ribs in each whorl with clefts of a similar width between them, sculptured with further fine riblets. This gives a fluted edge to the lip and the grooves can also be seen on the interior surface of the shell. The central column or columella is smooth and the interior of the shell is white.
The western Australian form has a row of well marked nodules rather than ridges and an unindented lip while the southern Australian form has much less distinct ridges and a nearly smooth lip. [2] At one time it was thought that these different forms were distinct species but it has now been established that the variations in sculpture are a function of different living conditions. Specimens gathered from New South Wales with deep ridges were kept in a still water aquarium for three years during which time the new shell growth was at first shallowly indented and later was smooth. [2]
The colour of the shell is generally creamy white or grey, often with a thin yellowish line round the margin of the lip. [2] Juveniles have thinner shells and are often brown. [3]
This snail is plentiful in the intertidal zone and sublittoral zone on rocks and among seaweed around the coasts of Australia (New South Wales, Queensland, South Australia, Tasmania, Victoria, Western Australia), New Zealand, Kermadec islands and Lord Howe Island. [3] [4]
The white rock shell is a predator, cannibal and scavenger. [5] It uses its radula to bore a hole in the shell of a barnacle or mollusc and then sucks out the contents. Prey species include the sea snails Lunella torquata , [2] Cronia avellana and Pyrene bidentata , and the mussel Septifer bilocularis . [5] As the tide rises, the white rock shell makes foraging expeditions up the beach, travelling far away from the sheltered niches to which it retreats at low tide. This is in contrast to the mulberry whelk Morula marginalba which shares the same habitat but remains in an area where there are both crevices in which to hide and prey species on which to feed. [6]
The sexes are separate in the white rock shell. The eggs that develop in the female gonoduct are wrapped in a number of membranes to form an egg capsule. Several of these are joined together in an egg mass and attached to the substrate. Different precursors of the pigment Tyrian purple have been found in the male and female gonoducts and in the egg capsule. [7] Early development of the larvae takes place inside the capsule which contains yolk granules on which they feed. When they have developed to the veliger stage, the larvae emerge from the capsule and become planktonic. After drifting with the currents for a while, these settle on the seabed, undergo metamorphosis and become juvenile snails. [8]
Tyrian purple, also known as, royal purple, imperial purple, or imperial dye, is a reddish-purple natural dye. The name Tyrian refers to Tyre, Lebanon. It is secreted by several species of predatory sea snails in the family Muricidae, rock snails originally known by the name Murex. In ancient times, extracting this dye involved tens of thousands of snails and substantial labor, and as a result, the dye was highly valued. The colored compound is 6,6′-dibromoindigo.
Muricidae is a large and varied taxonomic family of small to large predatory sea snails, marine gastropod mollusks, commonly known as murex snails or rock snails. With over 1,700 living species, the Muricidae represent almost 10% of the Neogastropoda. Additionally, 1,200 fossil species have been recognized. Numerous subfamilies are recognized, although experts disagree about the subfamily divisions and the definitions of the genera. Many muricids have unusual shells which are considered attractive by shell collectors and by interior designers.
Nucella, common name dog whelks or dog winkles, is a genus of small to medium-sized predatory sea snails, marine gastropod mollusks in the subfamily Ocenebrinae which is part of the large family Muricidae, the murex snails or rock snails.
The knobbed whelk is a species of very large predatory sea snail, or in the US, a whelk, a marine gastropod mollusk in the family Busyconidae, the busycon whelks.
Busycon is a genus of very large edible sea snails in the subfamily Busyconinae. These snails are commonly known in the United States as whelks or Busycon whelks. Less commonly they are loosely, and somewhat misleadingly, called "conchs".
Rapana venosa, common name the veined rapa whelk or Asian rapa whelk, is a species of large predatory sea snail, a marine gastropod mollusc or whelk, in the family Muricidae, the rock shells.
Thais, sometimes known by the common names dog winkles or rock shells, is a genus of medium to large predatory sea snails with an operculum, marine gastropod mollusks in the family Muricidae.
Haustrum haustorium, common name: the brown or dark rock shell, is a large species of predatory sea snail, a marine gastropod mollusc in the family Muricidae, the murex snails or rock snails.
Haustrum is a genus of sea snails, marine gastropod mollusks in the subfamily Haustrinae of the family Muricidae, the murex snails or rock snails.
Stramonita haemastoma, common name the red-mouthed rock shell or the Florida dog winkle, is a species of predatory sea snail, a marine gastropod mollusc in the family Muricidae, the rock snails.
The mangrove murex is a species of sea snail, a marine gastropod mollusk in the family Muricidae, the murex snails or rock snails.
Muricanthus radix, the radix murex or root murex, is a species of sea snail, a marine gastropod mollusk in the family Muricidae, the murex snails or rock snails.
Nucella lamellosa, commonly known as the frilled dogwinkle or wrinkled purple whelk, is a species of sea snail, a marine gastropod mollusk in the family Muricidae, the murex snails or rock snails. This species occurs in the eastern Pacific Ocean, its range extending in the intertidal zone from the Aleutian Islands southward to central California.
Nucella ostrina, the northern striped dogwinkle, is a species of sea snail, a marine gastropod mollusk in the family Muricidae, the murex snails or rock snails. Other common names for this mollusk include emarginate dogwinkle, short-spired purple dogwinkle, striped dogwinkle, ribbed dogwinkle, emarginate whelk, ribbed rock whelk, rock thais, short-spired purple snail and rock whelk.
Neothais is a genus of sea snails, marine gastropod mollusks in the subfamily Rapaninae of the family Muricidae, the murex snails or rock snails.
The hypobranchial gland is a glandular structure which is part of the anatomy of many mollusks, including several different families of gastropods, and also many protobranch bivalves. This gland produces mucus as well as biologically active compounds. The cephalopod ink sac is a modified hypobranchial gland.
Cominella lineolata, common name the spotted cominella, is a species of predatory sea snail, a marine gastropod mollusc in the family Cominellidae,.
Oppomorus noduliferus, common name the nodule castror bean, is a species of sea snail, a marine gastropod mollusk in the family Muricidae, the murex snails or rock snails.
Nassarius pauperatus, commonly known as the impoverished dog whelk, is a species of sea snail, a marine gastropod mollusk in the family Nassariidae, the nassa mud snails, or dog whelks.
Tenguella marginalba is a species of sea snail, a marine gastropod mollusc in the family Muricidae, the murex snails or rock snails. It is commonly known as the mulberry whelk and is found in shallow waters in the Indo-Pacific and around the north and east coasts of Australia.
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