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Records of the Australian Museum (2017) Vol. 69 
the isopod genus Idotea also cling to neustonic organisms, 
as well as to flotsam (Cheng, 1975: 201) and could be 
considered to be semi-neustonic in the same way as Fiona 
and Litiopa are. Physalia, Porpita and Velella are merely 
the most common and familiar of neustonic cnidarians. 
Hardy (1956: 114-122, fig. 31) described 10 other similar 
cnidarians occurring in British waters, although apparently 
none of them is cast ashore. Various small animals such as 
hydroids also are found attached to some Janthina shells. The 
water-strider insects, five species of the family Halobatidae 
(Herring, 1961) were included by David (1965: 99, fig. 3) 
in a category of their own, the epineuston, as they walk on 
the surface film of the ocean rather than being immersed 
in water. The species of Glaucus float upside-down at the 
sea surface buoyed by a bubble of gas in their stomach 
(Rudman, 1998: 1015). Their taxonomy was revised by 
Valdes & Campillo (2004) and Churchill et al. (2014). The 
“heteropods” (Pterotracheoidea; Thiriot-Quievreux, 1973; 
Wall-Palmer et al ., 2016) and “pteropods” (Thecosomata 
and Gymnosomata; Lalli & Gilmer, 1989; Newman, 1998) 
also are holoplanktonic oceanic gastropods, but they are 
much more highly specialized than Janthina and Recluzia. 
They have a highly modified shell or no shell at all, swim 
actively at various levels in the ocean, and are not part of the 
neuston. Smith (1998: pi. 24, fig. 4) illustrated a specimen of 
Janthina janthina (Linnaeus, 1758) in normal life position 
suspended beneath its float, feeding on the siphonophore 
Physalia physalis. The illustrated Janthina shell is covered 
densely with Lepas barnacles. This illustration conveys the 
appearance of the small neustonic community well. 
Distribution. Like other neuston, Janthina and Recluzia float 
passively at the sea surface in mid-ocean. Early travellers 
described the enormous numbers of Janthina specimens 
found in mid-ocean in extensive but localized “rafts”, e.g., 
“In lat. 2°53'S., long. 176°55'E., a remarkable white line 
was observed on the surface of the ocean ... It proved to be 
an undulated line of froth , or scum, several yards in width, 
extending on either side as far as was visible by the naked 
eye, and accompanied by a heterogeneous assemblage of 
floating mollusks, small fish, crabs, other marine animals 
and oceanic birds. ... Janthinae , or sea-snails, were the 
most abundant of the floating mollusks. Their number was 
immense; and their floats contributed greatly to the white 
appearance of the froth-line” (Bennett, 1840: 62-63; Italics 
original). Benson (1860) gave a very full account of abundant 
specimen of Janthina and a few specimens of Recluzia 
observed at sea and captured with towing nets, during a 
voyage from England to Calcutta in the sailing ship Malcolm. 
Among other descriptions, he noted that “As we approached 
the Tristan d’Acunha group, in the Southern Atlantic, we 
sailed for several days through a tract, from 30° S. lat. and 
18° W. long, to 33° S. and 10° W., inhabited by a fine white 
and violet-coloured Ianthina pallida , Harvey, in company 
with a large variety of I. exigua ” (Benson, 1860: 407; it is 
not clear that this was a single dense raft of specimens). 
Morch (1860: 271, footnote) appended the following 
description: “M. Luwigson told me that, in the Chinese seas, 
he observed at a certain distance from the vessel something 
white ... Examined closely, it was nothing but an enormous 
accumulation of Janthines ...” (translation from French). 
Laursen (1953:14) also quoted Simroth (1895) who recorded 
a “shoal” of Janthina specimens in the Atlantic 200 nautical 
miles across. Janthina specimens are familiar to most people 
only when cast ashore from time to time during prolonged 
on-shore winds. Wilson & Wilson (1956: 291-296) pointed 
out the close association between Janthina strandings 
in Cornwall and persistent, unusually strong westerly to 
north-westerly winds. The association also has always been 
obvious in New Zealand between persistent westerly winds 
and the stranding of Janthina specimens, accompanied by 
Velella and Physalia , along the west coast between Auckland 
(particularly Piha to Muriwai Beaches and western Awhitu 
Peninsula) and Wellington (particularly beaches along 
the Kapiti coast). The long, north-south-oriented western 
coasts of New Zealand and the southern coast of Australia 
provide excellent traps for neustonic animals in a region 
of predominantly westerly winds. Abbott (1974: 113) also 
stated that J. janthina is “common after certain easterly blows 
along the southeastern United States, especially from April 
to May”. Risbec (1953: 194) also described specimens of 
Janthina cast ashore in New Caledonia after violent winds 
blowing in the same direction for a long time, perpendicular 
to the coast at Magenta Beach and Anse Vata. Janthina 
specimens become conspicuous when cast ashore because 
of their violet shells, and are known in English as “purple 
snails” or “violet snails”. However, the yellow-brown shells 
of the two Recluzia species recognized here, Recluzia johnii 
(Holten, 1802) and R lutea (Bennett, 1840), are much less 
common and conspicuous. Accounts of the stranding of 
specimens of Janthina and Recluzia , particularly along 
the southern and western coasts of Britain, including the 
Scilly Isles, but also in Australia, India, Japan, Kenya, New 
Caledonia, New Zealand, Spain, Sicily, and USA have 
been published by numerous authors (e.g., Grant, 1833; 
Dillwyn, 1840: 59; Jeffreys, 1867: 174; Smart & Cooke, 
1885; Simpson, 1897; Russell & Kemp, 1932; Dakin, 1933; 
Ramanujam, 1935; Rogers, 1941; Fowler, 1946a, b, 1947, 
1948, 1949; Habe & Tokioka, 1953; Risbec, 1953: 194; 
Wilson & Wilson, 1956; Wilson, 1958; Dakin, 1960: 251, 
Figure 2 (facing page 123). Shells of the five living species of Janthina and two species of Recluzia recognized in this work; apertural 
views, and left lateral views showing outer lip sinus. (A—F) Janthina janthina (Linnaeus); A-B, D, GNS RM4442, two specimens, beach, 
Takou Bay, Northland, New Zealand; C, GNS WM15986, “bicolor” fomi, San Louren^o Beach, Santa Maria I., Azores, Atlantic; E, GNS 
RM6735, “bicolor” form, Ohope Beach, Whakatane, New Zealand; F, GNS WM15297, beach between Hutchinson Bluff and Rayner 
Point, Raoul I., Kermadec Islands. (G-J) Janthina globosa (Swainson); G, GNS WM15254, beach, Mauritius, Indian Ocean; H-J, GNS 
RM5321, two specimens, Muriwai Beach, West Auckland, New Zealand. (K-L) Janthina pallida Thompson, GNS WM15256, beach, 
Windy Harbour, Cape D’Entrecasteaux, southern Western Australia. (M, O) Janthina exigua Lamarck, GNS RM5626, Nukumaru Beach, 
Whanganui, New Zealand. (N, Q) Janthina umbilicata d’Orbigny, GNS RM5627, Nukumaru Beach, Whanganui, New Zealand. (P, R) 
Recluzia johnii (Holten), GNS WM17360, ventral and dorsal views; trawled in sediment, 130-180 m, Swain Reefs, SE Queensland, 
Australia (shortest specimen, last entry in Table 12). (S-T) Recluzia lutea (Bennett), GNS RM6748, beach, Great Exhibition Bay, Northland, 
New Zealand (from same sample as Figs 36M-P). Scale bar 10 mm, applies to all figures. 
