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Xenophyophores are giant multinucleate organisms found throughout the world's oceans, at depths of up to 10,641 meters (6.6 miles). They were first described by Henry Bowman Brady in 1883 as primitive Foraminifera, and later they were placed within the sponges. In the beginning of the 20th century they were considered as an independent class of Rhizopoda, and later as a new eukaryotic phylum of Protista. Recent phylogenetic studies suggests that xenophyophores are a specialized group of monothalamous (single-chambered) Foraminifera. Xenophyophores have been described at depths greater than 500 meters and are more abundant on abyssal plains. Fourteen genera and approximately 60 species have been described; one particular species, ''Syringammina fragilissima'', is among the largest known syncitia, as it can grow up to 20 centimetres in diameter. ==Description== Xenophyophores are giant, multinucleate Foraminifera that are confined exclusively to depths below 500 metres. Their name Xenophyophora, which means "bearer of foreign bodies", comes from the Greek and refers to the sediments, called xenophyae, which are agglutinated (cemented together) to construct their tests. They are an important component of the deep sea-floor, as they have been found in all four major ocean basins.〔〔 However, so far little is known about their biology and ecological role in deep-sea ecosystems. They form delicate and elaborate agglutinated tests that range from a few millimetres to 20 centimetres. Species of this group are morphologically variable, but the general structural pattern includes a test enclosing a branching system of organic tubules together with masses of waste material (stercomata).〔 They are often found in areas of enhanced organic carbon flux, such as beneath productive surface waters, in sub-marine canyons, in settings with sloped topography (e.g. seamounts, abyssal hills) and on continental slopes.〔〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「xenophyophore」の詳細全文を読む スポンサード リンク
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