挑食！以死亡魷魚的喙為食的海螺(原創(chuàng) 克爾-紐曼黑洞)

1888年，摩納哥王儲阿爾貝于亞速爾群島外海約780英尋（約相當(dāng)于1427米）深度拖網(wǎng)獲得一塊頭足類喙的殘骸。殘骸上棲息著許多微型笠螺，多個(gè)個(gè)體啃咬出與貝殼基部大小相當(dāng)?shù)陌伎樱袝r(shí)坑底僅存一層透明薄膜。12年后，Dautzenberg與Fischer根據(jù)這些標(biāo)本建立淵喙螺科Bathysciadiidae。

淵喙螺科是種粒螺目Cocculinida僅有的3個(gè)科之一。全科共4屬9種，大多棲息于數(shù)千米深的海底，加之其以死亡魷魚喙為食的習(xí)性，因此十分罕見。盡管曾有在一個(gè)大王烏賊喙上發(fā)現(xiàn)百余個(gè)淵喙螺Bathysciadium costulatum個(gè)體的記錄，但據(jù)2023年的一篇論文統(tǒng)計(jì)，全世界記錄在案的博物館館藏僅有35批。稀少的發(fā)現(xiàn)令淵喙螺的相關(guān)研究極少。

淵喙螺擁有標(biāo)志性的具放射狀流蘇的殼皮，和蟶螂一樣殼皮長于殼體，其作用也和蟶螂的相似——當(dāng)動(dòng)物抬高身體以便水流過貝殼與其基座之間時(shí)，這些流蘇覆蓋兩側(cè)，使得沉積物無法進(jìn)入貝殼與基座之間。淵喙螺的足部會(huì)形成類似吸盤的結(jié)構(gòu)，也是唯一完全缺失中腸腺的非寄生腹足類。淵喙螺殼體脆弱，以至于在干燥環(huán)境中，Bathysciadium costulatum的外殼會(huì)因殼皮收縮而碎裂。在Bathysciadium costulatum的胃中曾發(fā)現(xiàn)刮削下的頭足類喙碎片，推測其依靠共生菌消化這些碎片。

Bathysciadium xylophagum是唯一被發(fā)現(xiàn)于木材上的淵喙螺，其棲息于船蛆的蛀洞中。這被認(rèn)為是在首選基質(zhì)不存在時(shí)的無奈選擇。在葡萄牙西南部外海約瑟芬海山發(fā)現(xiàn)的Bathysciadiumcf.xylophagum則棲息于頭足類喙上。除Bathysciadium xylophagum外，僅有2個(gè)來自科隆群島（加拉帕戈斯群島）的未命名Xenodonta屬物種確認(rèn)不以頭足類的喙為食——它們附著在一個(gè)尖帽螺科Capulidae個(gè)體的殼上并吞噬了它的大部分殼皮。

Bathysciadium xylophagum/ 作者拍攝自有標(biāo)本

Bathysciadium xylophagum（圖中a、b）

Bathysciadiumcf.xylophagum（圖中c、d）

Xenodonta bogasoni

Bathysciadium pacificum生活的深度范圍極廣，在5500米、4000米至2000米水深都有發(fā)現(xiàn)，甚至曾在一條捕獲自549~594米水深處的太平洋油鰈Microstomus pacificus的消化道內(nèi)發(fā)現(xiàn)過一個(gè)標(biāo)本。太平洋油鰈棲息深度為10~1370米。考慮其在冬季才向深水產(chǎn)卵洄游，而含B. pacificum的標(biāo)本于6月采集到，因此B. pacificum可能在500~800米也有分布。令人遺憾的是這枚標(biāo)本已經(jīng)遺失。

Bathysciadium pacificum/ Geiger et al, 2023

淵喙螺科的Pilus conicus

淵喙螺在生命早期就會(huì)失去胎殼，齒舌退化，齒數(shù)遠(yuǎn)少于正常的扇舌型古腹足類齒舌。魷喙螺科Teuthirostriidae的Teuthirostria cancellata盡管同樣棲息于頭足類喙上，卻擁有正常的種粒螺型齒舌。因此魷喙螺科可能代表著種粒螺科Cocculinidae與淵喙螺科之間的過渡——一些種粒螺首先改變食性，以頭足類喙為食，隨后齒舌和消化道因此而退化。魷喙螺科共2屬3種，除T. cancellata外，其余2種均棲息于沉木上。

魷喙螺科的Fedikovella beanii

魷喙螺科的Fedikovella caymanensis

參考文獻(xiàn)及圖片來源

Ardila N E, Harasewych M G, 2005. Cocculinid and pseudococculinid limpets (Gastropoda: Cocculiniformia) from off the Caribbean coast of Colombia[J]. Proceedings of the Biological Society of Washington, 118(2): 344-366.

Dall W H, 1908. Reports on the dredging operations off the west coast of Central America to the Galapagos, to the west coast of Mexico, and in the Gulf of California, in charge of Alexander Agassiz, carried on by the U.S. Fish Commission steamer "Albatross," during 1891, Lieut.-Commander Z.L. Tanner, U.S.N., commanding. XIV/XXXVII[M]. Bergh R, Agassiz A, United States. Bureau of Fisheries. Cambridge, Mass: Museum of Comparative Zo?logy.

Dall W H, 1927. Small shells from dredgings off the southeast coast of the United States by the United States Fisheries Steamer "Albatross", in 1885 and 1886[J]. Proceedings of the United States National Museum, 70(2667): 1-134.

Dautzenberg P, Fischer H, 1900. Description d'un mollusque nouveau[J]. Bulletin de la Société Zoologique de France, 24: 207-209.

Geiger D L, Thacker C E, 2023.Bathysciadium pacificumDall, 1908 from the bathyal of Oregon: range extension and anatomy (Gastropoda: Cocculinida: Bathysciadiidae)[J]. The Nautilus, 137(2): 35-44.

García E F, 2012. Noteworthy offshore mollusks from the north-central Gulf of Mexico, including geographical extensions and a generic reassignment[J]. American Conchologist, 40: 34-37.

Hartmann H, He? M, Haszprunar G, 2011. Interactive 3D anatomy and affinities of Bathysciadiidae (Gastropoda, Cocculinoidea): deep‐sea limpets feeding on decaying cephalopod beaks[J]. Journal of Morphology, 272(3), 259-279.

Haszprunar G, 1988. Comparative anatomy of cocculiniform gastropods and its bearing on archaeogastropod systematics[J]. Malacological Review, Supplement 4: 64-84.

Haszprunar G, Wendler S Y, J?st A B, et al, 2022. 3D-anatomy and systematics of cocculinid-like limpets (Gastropoda: Cocculiniformia): more data, some corrections, but still an enigma[J]. Zoomorphology, 141(2): 151-171.

Leal J H, Harasewych M G, 1999. Deepest Atlantic molluscs: hadal limpets (Mollusca, Gastropoda, Cocculiniformia) from the northern boundary of the Caribbean Plate[J]. Invertebrate Biology, 118(2): 116-136.

Locard A, 1897-1898. Expéditions scientifiques du Travailleur et du Talisman pendant les années 1880, 1881, 1882 et 1883. Paris: Masson.

McLean J H, Harasewych M G, 1995. Review of western Atlantic species of cocculinid and pseudococculinid limpets, with descriptions of new species (Gastropoda: Cocculiniformia)[J]. Contributions in Science, 453: 1-33.

Verrill A E, 1884. Second catalogue of mollusca recently added to the fauna of the New England Coast and the adjacent parts of the Atlantic, consisting mostly of deep sea species, with notes on others previously recorded[J]. Transactions of the Connecticut Academy of Arts and Sciences, 6(1): 139-294, pl. 28-32.

Warén A, 1991. New and little known Mollusca from Iceland and Scandinavia[J]. Sarsia, 76(1-2): 53-124.

Warén A, 1993. New and little known mollusca from Iceland and Scandinavia, Part 2[J]. Sarsia, 78: 159-201.

Warén A, 1997. Description ofBathysciadium xylophagumWarén & Carrozza, sp.n., and comments on Addisonia excentrica (Tiberi), two Mediterranean cocculiniform gastropods[J]. Bollettino Malacologico, 31(9-12): 231-266.

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