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The World’s largest known Gorgonian

Authors:
Les Watling at University of Hawaiʻi at Mānoa
Les Watling
Sonia J. Rowley at University of Hawaiʻi at Mānoa
Sonia J. Rowley
John M Guinotte at U.S. Fish and Wildlife Service
John M Guinotte
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Abstract

Gorgonians in the deep sea can be much larger than their shallow water counterparts, but there are only a few scattered measurements. We have estimated the size of a chrysogorgiid gorgonian, Iridogorgia magnispiralis Watling 2007, observed from a submersible on Twin Banks in the Northwest Hawaiian Islands, as being 5.7 m tall.
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198 Accepted by M. Daly: 4 Feb. 2013; published: 19 Mar. 2013
ZOOTAXA
ISSN 1175-5326 (print edition)
ISSN 1175-5334 (online edition)
Copyright © 2013 Magnolia Press
Zootaxa 3630 (1): 198–199
www.mapress.com
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zootaxa
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Correspondence
http://dx.doi.org/10.11646/zootaxa.3630.1.10
http://zoobank.org/urn:lsid:zoobank.org:pub:5B16D131-2DE6-439E-8176-2D78DD7D3911
The World’s largest known Gorgonian
LES WATLING1, SONIA ROWLEY1,2 & JOHN GUINOTTE3
1Department of Biology, University of Hawaii at Manoa, Honolulu, HI 96822, USA. E-mail: watling@hawaii.edu
2School of Biological Sciences, Victoria University of Wellington, Wellington, NZ. E-mail: soniajrowley@gmail.com
3Marine Conservation Institute, Seattle, WA 98103, USA. E-mail: john.guinotte@Marine-Conservation.org
Abstract
Gorgonians in the deep sea can be much larger than their shallow water counterparts, but there are only a few scattered
measurements. We have estimated the size of a chrysogorgiid gorgonian, Iridogorgia magnispiralis Watling 2007,
observed from a submersible on Twin Banks in the Northwest Hawaiian Islands, as being 5.7 m tall.
Introduction
As the bathyal depths of the ocean are explored with submarines and remotely operated vehicles, octocorals are more
routinely being imaged in situ. In Hawaii, octocorals are quite rare in shallow water (Devaney 1977; Cairns & Bayer
2008) but can be very common in water more than 160 m deep, with a total of 70 species currently known and another
20-30 still to be described (Grigg and Bayer 1976; Watling personal observation). While most deep-sea gorgonians share
a similar size range as those from the shallow tropics, a few species, primarily in the families Chrysogorgiidae Verrill,
1883, and Isididae Lamoroux, 1812, are much larger. For example, in the North Atlantic, the chrysogorgiid Iridogorgia
magnispiralis Watling 2007 was described as being more than 3 m tall (Watling 2007). In addition, an unidentified
bamboo coral measuring 3.8 m total length was collected from a depth of 2252 m on Kelvin Seamount in the New
England Seamount Chain (see oceanexplorer.noaa.gov/explorations/04mountains/logs/may19/may19.html) and some
very large specimens of Paragorgia Milne-Edwards and Haime, 1857, have been brought up by trawlers fishing along
the slopes of the Chatham Rise. These are massive, but so far do not appear to exceed 2 m in height (e.g. http://
www.greenpeace.org/international/en/news/features/Landmark-for-deep-sea240507/).
Material and methods
Specimens were observed from the submersible Pisces IV, operated by the Hawaii Undersea Research Lab, during dive
P5-224 on Twin Banks (23°03.005’N, 163°09.233’W, 1366 m, 28 November 2009), within the Papah
ā
naumoku
ā
kea
Marine National Monument (Permit number PMNM 2009-053). While the colony was not sampled, a nearby colony was
sampled to verify species identification. Measurements were made using the program ImageJ (Rasband 1997-2012) from
images taken while laser beams were focused along the colony axis. The two lower laser points were 19.9 cm apart (Fig.
1, inset).
Results and discussion
During a dive on Twin Banks, a specimen of Iridogorgia magnispiralis was imaged, but not collected, that is possibly the
largest gorgonian ever observed (Fig. 1). Using the program ImageJ the total length of the colony was estimated to be 5.7
m. This measurement does not include the additional length attributable to the coiling of the central axis in the part of the
colony where branches are present. The branches themselves are approximately 50 cm long, giving the colony an
average width of 1.1 m when the approx. 10 cm diameter of the coil is included.
Zootaxa 3630 (1) © 2013 Magnolia Press · 199
THE WORLD’S LARGEST KNOWN GORGONIAN
There were many I. magnispiralis colonies at this site; all were large, generally in the range of 3 m or so in overall
length. Most noticeable was the complete lack of young colonies. In other areas, such as the New England Seamounts,
where we have observed this species, very small (i.e., the colony consists of an axis only partially coiled) and
intermediate sized colonies (the axis has few coils; see Watling 2007, Fig. 2a) are usually present. The absence of
juveniles suggests that Twin Banks only very rarely experiences recruitment of new individuals. Rarely in this instance
might mean once a century or more since most octocorals live to be anywhere from 100-400 years (Watling et al. 2011).
FIGURE 1. The 5.7 m long specimen of Iridogorgia magnispiralis Watling, 2007, photographed at a depth of 1366 m on
Twin Banks, Northwest Hawaiian Islands within the Papah
ā
naumoku
ā
kea Marine National Monument. Inset shows laser
dots spaced at 19.9 cm used for measuring colony dimensions.
Acknowledgements
We thank C. Kelley and the Hawaii Undersea Research Lab who made the dive available to us, and passed on the laser
beam calibration measurements, the pilots and crew of the Pisces submersibles and research vessel Ka‘imikai-o-Kanaloa
for their expertise and help.
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... The genus Iridogorgia is an easily recognized octocoral group which is characterized by a remarkably spiral structure and large size at water depths of 558-2311 m [4][5][6][7]. The species Iridogorgia magnispiralis Watling, 2007 is a representative, which is known as the world's largest gorgonian reaching about 5.7 m tall [8]. ...
... Among them, four species are found in the North Atlantic, especially on the seamounts of the Northwest Atlantic, including I. pourtalesii Verrill, 1883, I. magnispiralis Watling, 2007, I. splendens Watling, 2007 and I. fontinalis Watling, 2007 [4,10,11]. Two species are recorded off the coast of Hawaii: I. bella Nutting, 1908 and I. magnispiralis [4,8,[11][12][13]. The diversity of Iridogorgia in the Western Pacific is still poorly known, I. magnispiralis was found in the Phoenix area and Northeast Australia [6,14], and I. densispicula Xu, Zhan, Li and Xu, 2020 and I. squarrosa Xu, Zhan, Li and Xu, 2020 are found in the seamounts near the Mariana Trench [7]. ...
... Distribution. The western Corner Rise Seamounts to the New England Seamounts to Kelvin Seamount, and the Lost City site on the Mid-Atlantic Ridge, 1650-2400 m [4]; Hawaii, 1310-1366 m [6,8]; Phoenix Islands Protected Area, 1000-2000 m [14]; Northeast Australia, 728-777 m [6]; a seamount located on the Caroline Ridge, 845 m. ...
Morphological and Molecular Characterization of Five Species Including Three New Species of Golden Gorgonians (Cnidaria: Octocorallia) from Seamounts in the Western Pacific
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  • Jun 2021
Simple Summary Deep-water octocorals are main components of vulnerable marine ecosystems (VMEs) and play an important role in conservation and research. Iridogorgia Verill, 1883 is a distinct octocoral group characterized by a remarkably spiral structure and large size in deep sea, where the diversity of Iridogorgia is poorly known in the Western Pacific. Based on the collection of Iridogorgia specimens from seamounts in the tropical Western Pacific, we described five species including three new species using an integrated morphological-molecular approach. We assessed the potential of the mitochondrial genes MutS and COI, and the nuclear 28S rDNA for species delimitation and phylogenetic reconstruction of Iridogorgia. The results suggest that the mitochondrial markers are not able to resolve the species boundaries and deeply divergent relationships adequately, while 28S rDNA showed potential application in DNA barcoding and phylogenetic reconstruction for this genus. This study will help to understand the Iridogorgia biodiversity in the Western Pacific and shed more light on the screening of barcodes for octocorals. Abstract Members of genus Iridogorgia Verrill, 1883 are the typical deep-sea megabenthos with only seven species reported. Based on an integrated morphological-molecular approach, eight sampled specimens of Iridogorgia from seamounts in the tropical Western Pacific are identified as three new species, and two known species I. magnispiralis Watling, 2007 and I. densispicula Xu, Zhan, Li and Xu, 2020. Iridogorgia flexilis sp. nov. is unique in having a very broad polyp body base with stout and thick scales. Iridogorgia densispiralis sp. nov. can be distinguished by rods present in both polyps and coenenchyme, and I. verrucosa sp. nov. is characterized by having numerous verrucae in coenenchyme and irregular spindles and scales in the polyp body wall. Phylogenetic analysis based on the nuclear 28S rDNA indicated that I. densispiralis sp. nov. showed close relationships with I. splendens Watling, 2007 and I. verrucosa sp. nov., and I. flexilis sp. nov. formed a sister clade with I. magnispiralis. In addition, due to Rhodaniridogorgia fragilis Watling, 2007 nested into the Iridogorgia clade in mtMutS-COI trees and shared highly similar morphology to the latter, we propose to eliminate the genus Rhodaniridogorgia by establishing a new combination Iridogorgia fragilis (Watling, 2007) comb. nov. and resurrecting I. superba Nutting, 1908.
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... bella Nutting, 1908, most of them were found from the North Atlantic Ocean, one also from the Pacific Ocean, and one only from the Central Pacific Ocean. So far, only I. magnispiralis Watling, 2007 was found from the Western Pacific Ocean (Pante et al. 2012, Watling et al. 2013. ...
... The genus Iridogorgia Verrill, 1883 contains five known species. Among these, I. pourtalesii Verrill, 1883, I. splendens Watling, 2007and I. fontinalis Watling, 2007 were found only from the North Atlantic Ocean (Verrill 1883, Watling 2007, I. bella Nutting, 1908 only from the Central Pacific Ocean (Nutting 1908), and I. magnispiralis Watling, 2007 from both the North Atlantic and Central Pacific Ocean (Watling 2007, Watling et al. 2013). The two new species described here were discovered from the tropical Western Pacific Ocean. ...
Morphology and phylogenetic analysis of two new species of deep-sea golden gorgonians (Cnidaria: Octocorallia: Chrysogorgiidae) from seamounts in the Western Pacific Ocean
Article
Full-text available
  • Feb 2020
Two new species of deep-sea chrysogorgiid gorgonians are described from the tropical Western Pacific: Iridogorgia densispicula n. sp. from an unnamed seamount in the Caroline Plate with water depth of 1204 m and Iridogorgia squarrosa n. sp. from an unnamed seamount near the Mariana Trench with water depth of 1458 m. Iridogorgia densispicula n. sp. has a slender stem with bud-like polyps, dense sclerites in polyps and branches, spindle-like scales in polyp bases, and long rods in tentacles. Iridogorgia squarrosa n. sp. has a brown to nearly black axis, large polyps with eight obvious columns, elongated scales in the back of tentacles, and special scales at base of polyps with many sculptures. By the combination of these features, the two new species differ distinctly from each other and all other congeners. Phylogenetic analyses indicate that I. densispicula n. sp. is sister to all other Iridogorgia Verrill, 1883, while I. squarrosa n. sp. showed close relationship with I. splendens Watling, 2007.
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... Dense 'forests' of these fauna can occur, providing additional three-dimensional structure to the habitat that support a range of associated fauna, including crustaceans, echinoderms, and molluscs. Some coral and sponge individuals are known to grow very large (e.g. the octocoral Iridogorgia magnispiralis up to 5.7 m tall) and live for more than 4000 years (Roark et al. 2009;Jochum et al. 2012;Watling et al. 2013;Wagner and Kelley 2017). Communities inhabiting ferromanganese-encrusted seamounts and ridges are sensitive to mechanical disturbance and many have already been impacted by bottom trawling and other types of fishing (Schlacher et al. 2014). ...
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A review of the genus Iridogorgia (Octocorallia: Chrysogorgiidae) and its relatives, chiefly from the North Atlantic Ocean
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Full-text available
  • Apr 2007
  • J MAR BIOL ASSOC UK
Exploration of the New England and Corner Rise Seamounts produced four new species of chrysogorgiid octocorals with the spiral iridogorgiid growth form. Three species are described as new in the genus Iridogorgia and one is described in the new genus Rhodaniridogorgia. Both genera have representatives in the Atlantic and Pacific Oceans. Iridogorgia magnispiralis sp. nov., is one of the largest octocorals encountered in the deep sea and seems to be widespread in the Atlantic.
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A Review of the Octocorallia (Cnidaria: Anthozoa) from Hawai‘i and Adjacent Seamounts: The Genus Narella Gray, 18701
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  • Jan 2008
The nine Hawaiian species of Narella are revised, including the description of six new species. All species but one (N. ornata) are described and illustrated using SEM; all species are keyed and included in a detailed table of comparison. A brief history of octocoral taxonomic research in the Hawaiian Islands is presented, resulting in a total of 90 named species for this region, only five of which occur in shallow water. Specimens were collected from throughout the archipelago and adjacent seamounts, including Cross, Pensacola, Bishop, and Bushnell, from depths of 326 to 1,977 m.
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Biology of Deep-Water Octocorals
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  • Dec 2011
  • ADV MAR BIOL
This chapter discusses the taxonomy, phylogeny, biogeography, ecology, and reproductive biology of deep-sea octocorals and also focuses on gorgonian octocorals because they are the predominant octocoral group in the deep sea. The most widely accepted taxonomic scheme for octocorals divides the subclass into four orders: (1) helioporacea, (2) alcyonacea, (3) gorgonacea, and (4) pennatulacea. The distinctions between most orders and suborders are blurred by intermediate taxa that resulted in a continuum of colonial organization and skeletal structure. The major areas of study of deep-sea gorgonians and sources of species descriptions are also summarized. Octocorals have been known from deep water in the North Atlantic, although the Challenger expedition showed that octocorals could be found in the depths of all oceans. Knowledge of deep-water octocorals of the Indo-West Pacific region is meagre and contrasts with the wealth of information on shallow-water taxa. The distribution of the three major deep-sea families' discussed are––chrysogorgiidae, isididae, and primnoidae. Deep-sea octocoral colonies are often large so it offers a wide range of biogenic habitats to other invertebrate species. The chapter also focuses on those invertebrate species that are found most frequently on the octocoral host. Reproduction, growth, age, food habits, and conservation issues are also considered.
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Present Knowledge of the Systematics and Zoogeography of the Order Gorgonacea in Hawaii
Article
  • Jan 1976
Past knowledge of the order Gorgonacea in Hawaii is based almost exclusively on the collections of the United States Fish Commission steamer Albatross in 1902, which contain 52 species. Recent efforts to investigate the ecology of precious coral have produced a new collection based on 183 dredge hauls and 10 dives with a submersible. This program is collectively referred to as the Sango Expedition. Of 59 species of gorgonians obtained by the Sango Expedition, 13 are considered to be new species and 28 new geographic records, bringing the total number of species considered to be present in Hawaii to 93 species. In contrast to the high diversity of gorgonians in the West Indies and the Indo-West-Pacific, the faunal list in Hawaii must still be considered depauperate. This is especially true in shallow water <75 m), where only one species is known. Although climatic deterioration during the Pleistocene could account for the scarcity of gorgonians in shallow water at the present time, this factor is unlikely to have affected deeper species. Furthermore, one would expect to find a modern complement of an ancestral faun a in shallow water if it had existed, as is true in the case of reef corals. The paucity of gorgonians in Hawaii may be due to isolation, which appears to have been a particularly effective barrier in shallow water. It is suggested that the only accessible route to Hawaii for gorgonians has been in deep water where, in the past, there were numerous stepping stones that may have aided dispersal. Moreover, chemical and physical gradients in deep water are relatively low. Why more deepwater species have not migrated into shallow water in Hawaii may be a reflection of their stenotypic character.
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Reef and Shore Fauna of Hawaii, Section 1: Protozoa through Ctenophora
  • Jan 1977
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Devaney, D.M. (1977) Octocorallia. In Devaney, D.M. & Eldredge, L.G. (Eds), Reef and Shore Fauna of Hawaii, Section 1: Protozoa through Ctenophora. Bernice P. Bishop Museum Special Publication 64(1), pp. 119-129.