''Fragum fragum'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of cockle, a marine

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...

mollusc Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...

in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Cardiidae A cockle is an edible marine bivalve mollusc. Although many small edible bivalves are loosely called cockles, true cockles are species in the family Cardiidae. MolluscaBase eds. (2022). MolluscaBase. Cardiidae Lamarck, 1809. Accessed through: W ...

. It is commonly known as the white strawberry cockle and is found in the western Indo-Pacific Ocean. It is the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

of the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

Fragum Fragum is a genus of cockles, marine bivalve molluscs in the family Cardiidae. Members of the genus have characteristic thick, sculptured shells and live buried in sand, extending their siphons to the surface to feed and breathe. They are found ...

''.

Description

''Fragum fragum'' grows to a length of . It has a pair of white, thick, sculptured valves with a

nacre Nacre ( , ), also known as mother of pearl, is an organicinorganic composite material produced by some molluscs as an inner shell layer; it is also the material of which pearls are composed. It is strong, resilient, and iridescent. Nacre is f ...

ous coating on the interior.

Distribution and habitat

''Fragum fragum'' is native to the tropical western Indo-Pacific Ocean. Its range extends from the East African coast and Madagascar to Polynesia, Japan and northern Australia. It is found at depths down to and lives buried in the sandy seabed.

Biology

''Fragum fragum'' lives buried in sand, extending its siphons to the surface to draw in water in order to filter feed and breathe. It has a

symbiotic Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasit ...

relationship with certain micro-algae, ''

zooxanthellae Zooxanthellae is a colloquial term for single-celled dinoflagellates that are able to live in symbiosis with diverse marine invertebrates including demosponges, corals, jellyfish, and nudibranchs. Most known zooxanthellae are in the genus ''Sy ...

'', which live in the mantle and other soft tissues. Its symbionts need a lower light intensity for

photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...

to take place than do those of the closely related species ''

Fragum unedo ''Fragum unedo'' is a species of cockle, a marine bivalve mollusc in the family Cardiidae, commonly known as the Pacific strawberry cockle. It is found in tropical seas in the Indo-Pacific region and the empty shells are prized for use in decorat ...

''. This means that ''Fragum fragum'' which also has a wider gape, can remain buried shallowly in the seabed whereas ''Fragum unedo'' needs to expose itself to light on the surface of the seabed, running a much greater risk of

predation Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill the ...

References

{{Taxonbar, from=Q13637513 Cardiidae Molluscs described in 1758 Taxa named by Carl Linnaeus