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ISSN 0001-4370, Oceanology, 2006, Vol. 46, No. 1, pp. 57–62. © Pleiades Publishing, Inc., 2006.Original Russian Text © A.K. Raiskii, E.P. Turpaeva, 2006, published in Okeanologiya, 2006, Vol. 46, No. 1, pp. 63–68.

INTRODUCTION

During recent years, the North Atlantic has becomethe object of much attention of biooceanologists due tothe intensive studies of seamounts, mid-ocean ridges,and at the sites of ship wrecks such as those of the

Titanic, Bismark

, and the

Komsomolets

nuclear subma-rine. The information on the composition of deep-waterspecies continues to be supplemented; meanwhile,even now, the database on the deep-sea animals is sig-nificantly greater than that used by N.G. Vinogradovato compile the schematic of zoogeographical zonationof the depths of the World Ocean [3, 14]. Due to thecrucial increase in the information on the deep-waterpycnogonids from different regions of the WorldOcean [1, 2, 4–13], it is of great interest to perform abiogeographical analysis of the sea spider speciesencountered in the North Atlantic at depths greaterthan 2000 m.

RESULTS

Sea spiders represent a common component of bot-tom biocoenoses. As it is seen from the published data,in the boreal and subtropical regions of the northernpart of the Atlantic Ocean, at sea depths greater than2000 m, 34 species of these animals were distin-guished. Below, we present the list of the pycnogonidsencountered in the North Atlantic and the regions oftheir distribution in the World Ocean.

SPECIES DISTRIBUTION

Nymphonidae Family

Nymphon inerme

Fage, 1956 (15 samples)—north-ern and central parts of the Atlantic Ocean, off SouthAfrica and New Zealand at sea depths of 3610–4410 m.

Nymphon laterospinum

Stock, 1963 (42 samples)—North and South Atlantic on either side of the Mid-Atlantic Ridge, southwestern part of the Indian Oceanat sea depths of 2608–4715 m.

Nymphon procerum

Hoek, 1881 (22 samples)—North and South Atlantic, northern and southeast-ern parts of the Pacific Ocean at sea depths of 2450–6135 m.

Nymphon tenellum

Sars, 1888 (10 samples)—Northwest Atlantic at sea depths of 392–2425 m.

Heteronymphon ponsitor

Child, 1982 (5 samples)—North American Basin at sea depths of 2022–2868 m.

Ammotheidae Family

Anisopes heteroscela

Child, Segonzac, 1996(7 samples)—hydrothermal fields of the Mid-AtlanticRidge at sea depths of 850–2400 m.

Ascorhynchus abyssi

Sars, 1881 (24 samples)—Northeast Atlantic and Arctic at sea depths of 1500–4000 m.

Deep-Sea Pycnogonids from the North Atlanticand Their Distribution in the World Ocean

A. K. Raiskii

1

and E. P. Turpaeva

2

1

Department of Biology, Moscow State University, Moscow, Russia

2

Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia

Received February 15, 2005; in final form, June 1, 2005

Abstract

—The information on the composition and distribution of present-day pycnogonids in differentregions of the World Ocean and, especially, in the northern part of the Atlantic Ocean acquired during the pastdecades allowed us to perform a biogeographical analysis of these animals, which represent a permanent com-ponent of bottom communities. For 34 species of sea spiders (Pycnogonida) found in the North Atlantic deeperthan 2 km, ten types of geographical distribution were recognized. Half of the species identified representAtlantic forms, and 41% of them are endemic forms with West-Atlantic, East-Atlantic, amphi-Atlantic, andcentral-Atlantic distributions. The other half of the deep-sea Atlantic species have broad geographical ranges.Among them, 11.7% are Atlantic–Pacific species, 14.7% dwell in the Atlantic and West Pacific, 8.9% are low-latitudinal panocaanic species, and 14.7% are panoceanic species able to penetrate to higher latitudes. The zoo-geographical species composition shows a significant independence of this fauna in the northern Atlantic Oceanand its relation to the Pacific and Indian oceans. At present, these relations are probably maintained via the tem-perate latitudes of the Southern Hemisphere and via the Drake Passage; meanwhile, it seems that, previously,they were realized possibly via the ancient Tethys Ocean.

DOI:

10.1134/S0001437006010073

MARINEBIOLOGY

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Ascorhynchus athernum

Child, 1982 (7 samples)—Northwest Atlantic at sea depths of 2862–3780 m.

Ascorhynchus ovicoxa

Stock, 1975 (5 samples)—Northwest Atlantic and Gulf of Mexico at sea depths of340–2223 m.

Ascorhynchus turritus

Stock, 1978 (10 samples)—North American Basin and Bay of Biscay at sea depthsof 2076–4411 m.

Ascorhynchus armatus

Wilson, 1881 (15 sam-ples)—Northwest Atlantic, Gulf of Mexico at seadepths of 396–2515 m.

Cilunculus tubicinis

Child, 1982 (1 sample)—Northeast Atlantic at a depth of 2868–2890 m.

Endeidae Family

Endeis spinosa

Montagu, 1808 (12 samples)—Northwest and Northeast Atlantic (Sargasso Sea; Ber-muda, Canary, and Antillean islands), Mediterraneanand Black seas, Gulf of Mexico at sea depths of 3–5000 m.

Callipallenidae Family

Callipallene acus

Meinert, 1898 (11 samples)—Northwest Atlantic at sea depths of 916–3800 m.

Pallenopsis calcanea

Stephensen, 1933 (13 sam-ples)—North and South Atlantic, northern part of thePacific Ocean at sea depths of 353–5615 m.

Pallenopsis guinensis

Stock, 1975 (3 samples)—Northeast Atlantic, Gulf of Guinea at sea depths of1949–4263 m.

Pallenopsis oscitans

Hoek, 1881 (5 samples)—northern and southern parts of the East Atlantic (WestEuropean Basin, Canary Basin, off the Cape of GoodHope) at sea depths of 1970–3550 m.

Pallenopsis longirostris

Wilson, 1881 (16 sam-ples)—Northwest and Northeast Atlantic, western partof the tropical zone of the Pacific Ocean (NewHebrides, Wanuatu islands) at sea depths of 142–2627 m.

Pallenopsis tydemani

Loman, 1908 (14 samples)—northwestern and northeastern regions of the AtlanticOcean, western part of the subtropical and tropicalzones of the Pacific Ocean (Indonesia, Japan, WanuatiIsland) at sea depths of 558–3356 m.

Pallenopsis mollissima

Hoek, 1881 (17 samples)—Northwest and Northeast Atlantic, western part of thetropical zone of the Pacific Ocean (Indonesia, NewCaledonoia) at sea depths of 909–3500 m.

Pallenopsis tritonis

Hoek, 1883 (10 samples)—Northeast Atlantic at sea depths of 2010–3690 m.

Phoxichilidiidae Family

Anoplodactylus maritimus

Hodgson, 1914 (17 sam-ples)—northwestern, northeastern, and tropical parts of

the Atlantic Ocean (tropical coast of South America),Gulf of Mexico at sea depths of 0–4379 m.

Anoplodactylus petiolatus

Kroyer, 1844 (33 sam-ples)—northwestern and southwestern parts of theAtlantic Ocean, western coast of Africa, the Mediterra-nean and Black seas at sea depths of 4–4825 m.

Anoplodactylus typhlops

Sars, 1888 (21 sample)—North and South Atlantic, western and eastern parts ofthe Pacific Ocean (Gulf of Alaska, waters off CentralAmerica, Northwest Basin, Tasman Sea) at sea depthsof 900–3796 m.

Austrodecidae Family

Pantopipetta longituberculata

Turpaeva, 1955(22 samples)–Northwest and Southeast Atlantic(North American Basin, Argentine Basin, Drake Pas-sage), Pacific Ocean (Peru–Chile and Kuril–Kam-chatka trenches, Bering Sea) at sea depths of 531–6710 m.

Colossendeidae Family

Colossendeis angusta

Sars, 1877 (72 samples)—Arctic, Atlantic, Pacific, and Indian oceans, subantarc-tic area at sea depths of 30–5340 m.

Colossendeis arcuata

Milne-Edwards, 1885 (7 sam-ples)—North Atlantic and southwestern part of thePacific Ocean at sea depths of 730–2084 m.

Colossendeis bicincta

Schimkewitsch, 1893(11 samples)—North Atlantic (North Atlantic Ridge,Bay of Biscay) and West Pacific oceans (Fiji Sea) at seadepths of 1900–4853 m.

Colossendeis clavata

Meinert, 1898 (34 samples)—eastern (Irish Trench, Bay of Biscay, Canary Islands)and western (North American Basin) parts of the NorthAtlantic at sea depths of 1540–3100 m.

Colossendeis colossea

Wilson, 1881 (64 samples)—Atlantic, Pacific, and Indian oceans, subantarctic areaat sea depths of 733–4844 m.

Colossendeis cucurbita

Cole, 1909 (17 samples)—North and South Atlantic, Pacific Ocean (northwesternand southwestern parts, waters off Central America) atsea depths of 591–4845 m.

Colossendeis macerrima

Wilson, 1881 (94 sam-ples)—Atlantic, Pacific, and Indian oceans at seadepths of 62–4306 m.

Colossendeis minor

Schimkewitsch, 1893 (19 sam-ples)—North and South Atlantic, Indian (Mid-IndianBasin) and Pacific (Yellow Sea, Marcus–Necker Sea-mounts) oceans at sea depths of 1035–4850 m.

Colossendeis minuta

Hoek, 1881 (11 samples)—Atlantic Ocean (North American basin, North AtlanticRidge, Walvis Ridge), Pacific Ocean (waters off Indo-nesia and Central America) at sea depths of 1026–3200 m.

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TYPES OF HABITATS

As a result of the analysis of the data on the findingsof each of the 34 species, we distinguished 10 types ofdistribution of the North Atlantic pycnogonids.

Central Atlantic habitat (

Anisopes heteroscela

).West Atlantic habitat (

Ascorhynchus armatus, Asco-rhynchus athernum, Ascorhynchus ovicoxa, Nymphontenellum, Heteronymphon ponsitor, Callipallene acus

).East Atlantic habitat (

Cilunculus tubicinis, Palle-nopsis guinensis, Pallenopsis oscitans, Pallenopsis tri-tonis

).Amphi-Atlantic habitat (

Ascorhynchus turritus,Colossendeis clavata, Endeis spinosa

).Pan-Atlantic habitat (

Anoplodactylus maritimus,Anoplodactylus petiolatus

).Arctic–Atlantic habitat (

Ascorhynchus abyssi

).Atlantic–Pacific habitat (

Nymphon procerum, Palle-nopsis calcanea, Pantopipetta longituberculata, Colos-sendeis minuta

).Atlantic–West Pacific habitat (

Colossendeis arcu-ata, Colossendeis bicincta, Pallenopsis longirostris,Pallenopsis mollissima, Pallenopsis tydemani

).Panoceanic low-latitudinal habitat (

Colossendeisminor, Nymphon inerme, Nymphon laterospinum

).

Panoceanic habitat of species able to penetrate tohigher latitudes (

Anoplodactylus typhlops, Colossen-deis angusta, Colossendeis colossea, Colossendeiscucurbita, Colossendeis macerrima

).

DISCUSSION OF THE RESULTS

As one can see from the above-presented list, thegeographical distribution of different species of theNorth Atlantic deep-sea pycnogonids is irregular. First,our attention is drawn to the habitats of 14 endemic spe-cies of the North Atlantic, whose distribution isrestricted to the boreal and tropical zones of the north-ern part of the Atlantic Ocean (Fig. 1). Among them, sixspecies refer to the West Atlantic habitat, four speciesrefer to the East Atlantic habitat, three species refer tothe amphi-Atlantic habitat, and only one species refersto the Central Atlantic habitat. In total, endemic speciescompose up to 41% of the species composition of thedeep-water pycnogonid fauna in the northern part of theAtlantic Ocean. A broader—Pan-Atlantic—habitat wasnoted for two species (6% of the total fauna); one spe-cies (3% of the fauna) also dwells in the Arctic Basin(Arctic–Atlantic habitat). Generally, all the Atlanticspecies comprise half of the species composition of thedeep-water pycnogonids in the North Atlantic.

123

4

5

Fig. 1.

Locations of findings of deep-water sea spiders that feature Atlantic habitats:

1

—Central Atlantic habitat;

2

—East Atlantichabitat;

3

—West Atlantic habitat;

4—

amphi-Atlantic habitat;

5

—pan-Atlantic habitat.

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The other half of the North Atlantic fauna of deep-water pycnogonids consists of widely spread species.Among them, four species (11.7% of the fauna) refer tothe Atlantic–Pacific habitat and five species (14.7% ofthe fauna) refer to the Atlantic–West Pacific habitat(Fig. 2). Other widely spread species are panoceanic;here, we distinguished two types of habitats: the pan-oceanic low-latitudinal habitat of three species (8.9%of the fauna) and the panoceanic habitat of five speciesable to penetrate to higher latitudes. The proportion ofthese five species in the deep-water pycnogonid faunaof the northern part of the Atlantic Ocean is 14.7%(Fig. 3).

Most of the above-listed pycnogonid species dwellin the bathyal zone, sometimes penetrating to the tran-sition zone between the bathyal and abyssal zones [2, 3.14]. All of them, except for

Endeis spinosa

, areendemic species of the North Atlantic; the

Pallenopsis

species (

P. longirostris, P. mollissima, P. tydemani

) areencountered in the North Atlantic and the northwesternpart of the Pacific Ocean and

Colossendeis minuta

is apanoceanic species. The range of their vertical distribu-tion lies within 1000–2800 m.

Of the six North Atlantic pycnogonids that pene-trated to the Southern Hemisphere, five speciesdescended to the lower abyssal zone; the range of the

vertical distribution of three of them (

Pallenopsisoscitans, Nymphon inerme

, and

N. laterospinum

) is2100–800 m. A very wide (3500–5000 m) range ischaracteristic of the panoceanic species and of thethree deep-water species able to ascend to the seasurface—

Endeis spinosa, Anoplodactylus mariti-mus

, and

A. petiolatus.

Alternatively, they are shal-low-water species that became capable of sinking togreat depths.

The character of the distribution of the deep-seapycnogonids of the northern part of the Atlantic Oceansuggests a significant independence of the sea spiderfauna of this region and allows one to infer the pres-ence of the process of species formation proceedingin the bathyal zone of this area. Meanwhile, the pres-ence of widely-spread deep-water species in theNorth Atlantic points to the existence of relations ofthe fauna of this region to other regions of the WorldOcean, which may be realized both on the bathyaland on the abyssal levels.

At present, one may outline three directions of thesekinds of relations. For the panoceanic species, the rela-tions between the Atlantic, Indian, and Pacific pyc-nogonids are probably maintained via the temperatelatitudes of the Southern Hemisphere. The linksbetween the Atlantic–Pacific species dwelling in the

123

Fig. 2.

Locations of findings of deep-water sea spiders that feature (

1

) the Arctic–Atlantic, (

2

) Atlantic–Pacific, and (

3

) Atlantic–West Pacific habitats.

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eastern and northwestern regions of the Pacific Oceanseem to be maintained via the Drake Passage, wherethese species were also encountered. As to the Atlantic–West Pacific species, there were no intermediate find-ings of them in the Indian Ocean. This suggests theabsence of a present-day connection between theAtlantic and West Pacific pycnogonid faunas. Mean-while, the presence of common species shows that thiskind of connection existed in the past. Therefore, onecan suppose that the North Atlantic and West Pacificpopulations of the same pycnogonid species (

Pallenop-sis longirostris, P. mollissima, P. tydemani, Colossen-deis arcuata, C. bicincta

) represent remnants of thefauna of the ancient Tethys Ocean, whose closureresulted in the separation of the habitats of these spe-cies.

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Bottom Fauna of the Greatest(Ultraabyssal) Depths of the World Ocean

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Deep-Sea Manned Submersibles

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1

2

Fig. 3.

Locations of findings of deep-water sea spiders that feature a panoceanic distribution:

1

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2

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12. J. H. Stock, “Abyssal Pycnogonida from the Northeast-ern Atlantic Basin. Part II,” Cahiers de Biologie Marine19, 397–413 (1978).

13. J. H. Stock, “Abyssal Pycnogonida from the WalvisBasin, Southern Atlantic,” Cahiers de Biologie Marine22, 453–471 (1981).

14. N. G. Vinogradova, “Zoogeography of the Abyssal andHadal Zones,” Advances in Marine Biology 32, 325–387(1997).