Marine snails 7 whelks

Syrinx aruanus, the Australian trumpet, the Giant whelk

Syrinx aruanus, the Australian trumpet also know as the Giant whelk below is a huge snail, the world's largest, that can grow to 91cm long and weigh 25kg! It is found in the intertidal zone down to around 50m deep around the northern Australian coast, southern New Guinea and Indonesia. It is carnivorous and feeds on polychaete worms. It has a long proboscis (up to 25cm long) and it uses this to reach into the tubes of its prey. Females produce large egg cases (15cm), which they attach to rocks, shells or gorgonian corals. It is sometimes eaten by humans and is used for fish bait.

Australian trumpet, Syrinx aruanis

Turnip whelk, Busycon coarctatum

The Turnip whelk, Busycon coarctatum below can be found down the East Mexican coast, and in contrast to the Lightning whelk, below, the turnip whelk coils clockwise.

Turnip whelk, Busycon coarctatum

Lightning whelk, Busicon contrarium

The Lightning whelk, Busicon contrarium, below, is found in shallow water from New Jersey down to Texas in estuaries, creeks and around oyster beds. Adults can grow up to 41cm long. The sexes are separate. They prey on clams, forcing the clam shell open with their foot, and holding open with the edge of their own shell.

Its common name comes from the lightning bolt shaped stripes seen on juvenile shells.

Lightning whelk, Busicon contrarium

Dog whelk, Atlantic dogwinkle, Nucella lapillus

The Dog whelk, Atlantic dogwinkle, Nucella lapillus, below, was used to make purple dye in Britain right up until the Romans invaded. It is found around the European and North West Atlantic coasts, mainly on rocky shores, where it prefers sheltered positions and crevices. Fully grown individuals are up to 4cm long, and have a life expectancy of 6 years or more.

The Dog whelk preys on shelled molluscs and crustaceans. Its radula bores a hole in the shell of the prey, at the same time as its foot secretes shell-softening chemicals. Once through the shell digestive enzymes are secreted turning the prey's body into soup. To consume a barnacle takes about a day, and a mussel about a month. Boring into a the tough shell of a limpet takes about 3 days. Mussels have developed a good defence against the dog whelk. They tie it down using byssus threads and leave the whelk to starve. Up to 30% of dog whelks invading mussel beds end up this way. The whelk itself is prey for birds and crabs.

TBT (tri butyl-tin), a chemical found in anti-fouling paint used on boats causes female dog whelks to develop a penis and sperm duct at concentrations less than 1 part per trillion. At 5 parts per trillion females are unable to release eggs, and the population will die out.

Dog whelk, Nucella lapillus