There are about 16 000 species in this Sub-class of marine shells. It contains many well known groups such as cones, augers, harps, murex, olives, volutes and whelks. Their internal anatomy relates them, even if the shells look widely different.
Many are very active hunters or scavengers. Cones are infamous for their poison barbs which can kill humans, and famous for the beauty of their shells.
Extensive habitat destruction and massiv over-collecting of some species threatens not only their survival but that of the eco-systems that they are part of.
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Conchs, Murex & Co.
These long, slender shells are closely related to cones. Like them, they have poison gland and harpoon-like teeth with which they kill their prey - marine worms. They are active burrowers in sand, but little is known of their biology.
Cones and cowries are perhaps the best known tropical snails. Their exotic patterns and coloration is offset by the deadly poison and highly effective dart delivery system for the poison has fascinated collectors for hundreds of years.
The fast acting deadly poison is an adaptation for some cones to enable them to catch fish. The Cone shoots a dart out from the pointed end of the shell. By the time the fish realises it has been attacked, the poison has worked and the fish is paralysed and is then consumed whole. The darts can be shot out a good 15 cm, so large cones should be approached with extreme caution and never ever handled. Cones are very aggressive and attack when threatened.
The shells look very like cowries at first glance, but as can be seen in the photos, the body is totally different. They are small and rarely seen.
These are active carniverous night hunters that bury themselves in the sand during the day. Their shell is very shiny and heavily ridged. Some species can break off a part of their large foot when attacked. The broken off piece writhes and distracts the predator while the Harp makes its' excape.
There are several hundred species of these carniverous and scavenging snails. They typically burrow in the sediment or sand and are most active at night, though I have seen Mitra species foraging during the day.
Murex Shells are a large family with many genera and species. They are all carniverous and many drill a small hole through the shell of their prey, softening the shell with acidic secretions. Species living in mud and sediment tend to have long thin spines which would make them difficult to eat, and stop them sinking through soft sediment. The species living in reefs or near mangroves have thicker, variously ornamented shells.
Males and females are separate with the females laying egg masses of various shapes.
Olives, dispite their superficial appearance, are not related to cowries. Their mantle covers their shell completely when then they forage. They are predators and scavengers often crawling just below the surface with only the tip of their siphon showing.
Vase Shell biology is very poorly know. They are active carnivores
Volutes are very active hunters, often feeding on other snails, as can be seen in the images of a cone being consumed. Note there that the cone is taken from the broad end, presumably avoiding the poison barb that can be shot out of the proboscis.
They have a well-developed, colourful foot, nerve and respiratory system, which enables them to move fairly quickly. When not hunting, they bury themselves in the sand.
This is a huge family with over 2000 species. All species are carniverous either preying on living molluscs or scavenging dead fish and other animals.