把木頭當飯吃，它們是深海木材分解者（下）（克爾-紐曼黑洞）

木材通過河流輸入等因素進入大海，并在被海水浸透后沉入深海，成為這片缺乏初級生產環境的特殊碳源。這些“有機島嶼”片段化且存在時間短暫，因此棲息于此的生物往往演化出長距離擴散策略。許多食木蛤（約35%的物種）殼表都有不挖洞的微型生物個體固著。研究者曾認為這些微型個體是食木蛤幼體，因此認為它們具有育幼習性。但后來的研究證實這些微型個體實際上是食木蛤的矮雄。矮雄以足絲固定在較大個體體表，僅有胎殼，營濾食生活。一些物種如Xylophaga supplicata的大的挖洞個體則是先雄后雌的雌雄同體，但其矮雄不能轉變為大的挖洞個體。另一些物種如Xylophaga dorsalis和Xylophaga depalmai則是雌雄異體。一些食木蛤的性別受環境影響，如雌雄異體的Xylonora atlantica在食物充足的新棲息地，性別比例會偏向雌性。隨著木材被第一世代持續消耗，食物與空間資源逐步減少，之后世代的雄性比例逐漸增加，最終導致幼體直接在雌性殼上定居，形成矮雄。

食木蛤的浮游幼體可以長時間維持浮游生活，大幅推遲變態時間。例如，Xylonora atlantica幼蟲可延遲變態達6個月之久，同時能進入遠離海底的上層海水。懸浮于海底上方20米水層中的木材仍可被大量食木蛤定殖，因此，一些物種分布范圍極廣，可跨海盆分布。但與此同時，由于深海沉木獲取困難，所以有大量食木蛤定殖的現象僅被發現過一次，有些物種甚至出現在遠離陸地的深淵平原或海溝，這些區域的木材沉降事件是極其罕見的。

一些食木蛤會選擇棲居的木材，如Abditoconus brava幾乎僅生活于松木而非橡木中，另一些則沒有這種偏好。后者的貝殼形態會因木材種類不同導致的硬度不同而出現變化。水深也會影響貝殼形態，但是食木蛤科本身的貝殼形態又高度趨同，因此僅依靠貝殼形態很難將食木蛤定種，而水管等軟體結構及其蛀道外部形態成為重要的分類依據。

Abditoconus brava/ Romano et a，2020

Abditoconus investigatoris。A–B. 正模TMAG E58320；C. TMAG E59292；D. 副模 2 TMAG E58316 / MacIntosh et al，2021

Spiniapex gilsonorum（TMAG E58450）/ MacIntosh et al，2021

參考文獻及圖片來源

Ablett J, Brown C, Gallichan J, et al, 2019. Mollusca Types in Great Britain[EB/OL]. Amgueddfa Cymru-National Museum Wales / Natural History Museum. https://gbmolluscatypes.ac.uk [Accessed: 16 July 2025].

Amon D J, Daniel S, Farah A, et al, 2015. Burrow forms, growth rates and feeding rates of wood-boring xylophagaidae bivalves revealed by micro-computed tomography[J]. Frontiers in Marine Science, 2(10): 00010.

Gaudron S M, Haga T, Wang H, et al, 2016. Plasticity in reproduction and nutrition in wood-boring bivalves (Xylophaga atlantica) from the Mid-Atlantic Ridge[J]. Marine biology, 163(10): 213.

Haga T, Kase T, 2008. Redescription of the deep-sea wood borerNeoxylophaga teramachiitaki & habe, 1950 and its assignment to the genusXyloredo(Bivalvia: Myoida:Pholadoidea) with comments on fossil photadoidae[J]. The Veliger, 50: 107-119.

Haga T, Kase T, 2013. Progenetic dwarf males in the deep-sea wood-boring genusXylophaga(Bivalvia: Pholadoidea)[J]. Journal of Molluscan Studies, 79(1): 90-94.

Harvey R, 1996. Deep waterXylophagaidae(Pelecypoda: Pholadacea) from the North Atlantic with descriptions of three new species[J]. Journal of Conchology, 35(6): 473-481.

Jayachandran P R , Velásquez M, Jima M, 2022. A new species of wood-boring bivalve (Mollusca: Xylophagaidae) from the Eastern Arabian Sea[J]. Marine Biodiversity, 52(1): 1-9.

Judge J, 2014. Testing relationships of a new form of boring bivalve: the interesting kind[J]. Friday Harbor Laboratories, http://hdl.handle.net/1773/27289.

Knudsen J, 1961. The bathyal and abyssalXylophaga(Pholadidae, Bivalvia)[J]. Galathea Reports. 5: 163-209.

Lai K Y, 2023. A new species of Xylophaga (Bivalvia: Xylophagaidae) from Taiwan[J]. 貝類學報, (6): 101-105.

Li Y, Altamia M A, Shipway J R, et al, 2022. Contrasting modes of mitochondrial genome evolution in sister taxa of wood-eating marine bivalves (Teredinidae and Xylophagaidae)[J]. Genome Biology and Evolution, 14(6): evac089.

Li Y, Halanych K M, 2017. Comparative genomics reveal symbiont-host evolution of deep-sea tubeworms (siboglinidae, annelida) and wood-boring bivalves (xylophagaidae, mollusca)[C]. 6th International Symposium on Chemosynthesis-Based Ecosystems. Woods Hole, Mass. USA. Augustus 2017.

MacIntosh H, Voight J R, 2021. Deep-sea wood-boring bivalves (Xylophagaidae) from southeast Australia, with a new species described[J]. Molluscan Research, 41(1): 16-25.

Romano C, Nunes-Jorge A, Le Bris N, et al, 2020. Wooden stepping stones: Diversity and biogeography of deep-sea wood boring Xylophagaidae (Mollusca: Bivalvia) in the North-East Atlantic Ocean, with the description of a new genus[J]. Frontiers in Marine Science, 7: 579959.

Romano C, Voight J R, Pérez-Portela R, et al, 2014. Morphological and genetic diversity of the wood-boringXylophaga(Mollusca, Bivalvia): new species and records from deep-sea Iberian Canyons[J]. PLoS ONE, 9(7): e102887.

Santhakumaran L N, 1980. Two new species ofXylophagafrom trondheimsfjorden, Western Norway (Mollusca, Pelecypoda)[J]. Sarsia North Atlantic Marine Science, 65(3): 269-272.

Turner R D, 2002. On the subfamily Xylophagainae[J]. Bulletin of the Museum of Comparative Zoology, 157(4): 223-307.

Voight J R, 2007. Experimental deep-sea deployments reveal diverse Northeast Pacific wood-boring bivalves of Xylophagainae (Myoida: Pholadidae)[J]. Journal of Molluscan Studies,73(4): 377-391.

Voight J R, 2008. Deep-sea wood-boring bivalves ofXylophaga(Myoida: Pholadidae) on the continental shelf: a new species described[J]. Journal of the Marine Biological Association of the United Kingdom, 88(7): 1459-1464.

Voight J R, 2009. Diversity and reproduction of near-shore vs offshore wood-boring bivalves (Pholadidae: Xylophagainae) of the deep eastern Pacific ocean, with three new species[J]. Journal of Molluscan Studies, 75(2): 167-174.

Voight J R, 2024. Three new species of wood-boring bivalves (Mollusca: Xylophagaidae) from the deep Northwest Atlantic Ocean[J]. Zootaxa, 5493(3): 275-290.

Voight J R, Heck P R, Du C, et al, 2022. Competition in the deep sea: phylogeny determines destructive impact of wood-boring xylophagaids (Mollusca: Bivalvia)[J]. Marine Biodiversity, 53: 1.

Voight J R, Marshall B A, Judge J, et al, 2019. Life in wood: preliminary phylogeny of deep-sea wood-boring bivalves (Xylophagaidae), with descriptions of three new genera and one new species[J]. Journal of Molluscan Studies, 85(2): 232-243.

Voight J R, Segonzac M, 2012. At the bottom of the deep blue sea: a new wood-boring bivalve (Mollusca, Pholadidae, Xylophaga) from the Cape Verde Abyssal Plain (subtropical Atlantic)[J]. Zoosystema, 34(1): 171-180.

文中部分圖片版權來源不詳，無法與著作權人一一取得聯系，未能及時支付稿酬，在此表示由衷的歉意。有關著作權人可與我們聯系。