Tonna perdix, common name : the partridge tun, is a very large species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of sea snail

Sea snail

Sea snail is a common name for those snails that normally live in saltwater, marine gastropod molluscs....

 or tun snail, a marine

Marine (ocean)

Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...

 gastropod mollusc in the family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Tonnidae

Tonnidae

Tonnidae is a family of medium-sized to very large sea snails, known as the tun shells. These are marine gastropod molluscs in the clade Sorbeoconcha and the clade Littorinimorpha.- Taxonomy :...

, the tun shells.

Description

The pattern and brownish colour of ther shell remind of a partridge

Partridge

Partridges are birds in the pheasant family, Phasianidae. They are a non-migratory Old World group.These are medium-sized birds, intermediate between the larger pheasants and the smaller quails. Partridges are native to Europe, Asia, Africa, and the Middle East...

. The size of an adult shell varies between 70 mm and 220 mm.

Distribution

This species is distribute din the Red Sea

Red Sea

The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez...

 and in the Indian Ocean along Aldabra

Aldabra

Aldabra, the world's second largest coral atoll, is in the Aldabra Group of islands in the Indian Ocean that form part of the Seychelles. Uninhabited and extremely isolated, Aldabra is virtually untouched by humans, has distinctive island fauna including the Aldabra Giant Tortoise, and is...

, Chagos, Madagascar

Madagascar

The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...

, the Mascarene Basin, Mauritius

Mauritius

Mauritius , officially the Republic of Mauritius is an island nation off the southeast coast of the African continent in the southwest Indian Ocean, about east of Madagascar...

  and Tanzania

Tanzania

The United Republic of Tanzania is a country in East Africa bordered by Kenya and Uganda to the north, Rwanda, Burundi, and the Democratic Republic of the Congo to the west, and Zambia, Malawi, and Mozambique to the south. The country's eastern borders lie on the Indian Ocean.Tanzania is a state...

; in the Pacific Ocean along New Zealand

New Zealand

New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

 and the Galapagos Islands.

External links

• Gastropods.com : Tonna (Perdix complex) perdix; accessed : 26 April 2011

Further reading

• Powell A. W. B.
  Arthur William Baden Powell
  Dr Arthur William Baden Powell CBE was a New Zealand malacologist, naturalist and palaeontologist, a major influence in the study and classification of New Zealand molluscs through much of the twentieth century. He was known to his friends and family by his third name, "Baden".Powell was born at...
  
  , William Collins Publishers Ltd, Auckland 1979 ISBN 0-00-216906-1