record so far of the ecological niche of white
sharks. Our results indicate that their range
is more pelagic than was previously thought,
comprising an inshore continental-shelf
phase as well as extensive oceanic travel. The
offshore phase lasted for at least 5 months,
suggesting that it is an important period in
the life history of white sharks in the North
Pacific. It is unclear whether these offshore
movements, which include extensive deep
dives, represent feeding or breeding migra-
tions. Increased tracking using electronic
tagging should provide more data about
the movement patterns, habitat usage and
potential fishery interactions of white
sharks, as well as critical information needed
for the conservation of this species.
Andre M. Boustany*, Scott F. Davis†,
Peter Pyle‡, Scot D. Anderson‡,
Burney J. Le Boeuf†, Barbara A. Block*
*Tuna Research and Conservation Center,
Stanford University and Monterey Bay Aquarium,
Hopkins Marine Station, Pacific Grove,
California 93950, USA
†Institute of Marine Sciences, University of
California at Santa Cruz, Santa Cruz,
California 95064, USA
‡Point Reyes Bird Observatory, Stinson Beach,
California 94970, USA
1. Metcalfe, J. D. & Arnold, G. P. Nature387, 665–666 (1997).
2. Block, B. A., Dewar, H., Farwell, C. & Prince, E. D. Proc. Natl
Acad. Sci. USA 95, 9384–9389 (1998).
3. Block, B. A. et al. Science293, 1310–1314 (2001).
4. Eckert, S. A. & Stewart, B. Environ. Biol. Fish.60,
5. Carey, F. G. & Teal, J. M. Comp. Biochem. Physiol. 28,
6. Compagno, L. J. V. FAO Fish. Synop.125, 1–249 (1984).
7. Klimley, A. P. Mem. South. Calif. Acad. Sci.9, 15–40 (1985).
8. Goldman, K. J., Anderson, S. D., McCosker, J. E. & Klimley, A.
P. in Great White Sharks: The Biology of Carcharodon
carcharias (eds Klimley, A. P. & Ainley, D. G.) 111–120
San Diego, 1996).
9. Klimley, A. P. et al. Mar. Biol.138, 617–636 (2001).
10.Hill, R. D. in Elephant Seals: Population Ecology, Behavior, and
Physiology (eds LeBoeuf, B. J. & Laws, R. M.) 227–236
(Univ. California Press, Berkeley, 1994).
11.Welch, D. W. & Everson, J. P. Can. J. Fish. Aquat. Sci.56,
12.Taylor, L. Mem. South. Calif. Acad. Sci. 9, 41–48 (1985).
Supplementary information accompanies this communication on
Nature’s website (www.nature.com).
Mass march of termites
into the deadly trap
thing that is careless enough to walk on
their slippery peristome, but Nepenthes
albomarginata is an exception. We show
here that this plant uses a fringe of edible
white hairs to lure and then trap its prey,
which consists exclusively of termites in
enormous numbers. This singular feature
accounts for the specialization of N. albo-
arnivorous pitcher plants of the genus
Nepenthes are not usually very selec-
tive about their prey, catching any-
NATURE | VOL 415| 3 JANUARY 2002| www.nature.com
Kahoolawe; three others (sharks 3, 4 and 6)
moved to a region of the subtropical eastern
Pacific (Fig. 1a). All four sharks showed a
period of bimodal preference for depths of
0–5 m and 300–500 m, spending up to 90%
of the day in these depth ranges and little
time at intermediate depths (Fig. 1b shows
representative data for shark 5). As the
sharks moved southwest, they increased their
maximum diving activity and experienced a
broader range of ambient temperatures. Sea-
surface temperatures rose to 20–26 ?C, and
the minimum temperatures at maximum
depths (650–680 m) dropped to 4.8 ?C
(Fig. 1c), suggesting that white sharks can
tolerate a broad temperature range.
The shark that travelled to Hawaii crossed
32? of longitude in 40 days at a minimum
velocity of 71 km per day (Fig. 1b). Although
sightings of white sharks in Hawaiian waters
are rare12, this individual remained in the
vicinity for almost 4 months, primarily stay-
ing between the surface and 300 m through-
out this period (Fig.1b).
These data provide the most extensive
Figure 1 Movem ents, diving and tem perature preference of white sharks. a, Deploym ent (red triangles) and end-point locations (white
circles) for sharks tagged with pop-up satellite archival tags. Deploym ent dates are given first, followed by pop-off dates. 1, 19 October
1999; 2 Novem ber 1999. 2, 30 October 1999; 25 Novem ber 1999. 3, 16 October 2000; 19 February 2001. 4, 10 Decem ber 2000;
9 April 2001. 5, 16 October 2000; 16 April 2001. 6, 5 Novem ber 2000; 8 May 2001. Sea-surface-tem perature im age is a weekly com -
posite for 21–28 February 2001. b, Longitude and depth distribution of shark 5 over the course of its 182-day tracking period. c, Data
for shark 5 over the course of the tracking period: black line, m axim um daily depth; red points, sea-surface tem perature; blue points,
m inim um daily tem peratures. Coastal residence is indicated by shallow m axim um depths (which correspond to the shark’s position over a
continental shelf), low sea-surface tem perature and narrow am bient tem perature range.
Feb 01Apr 01
Figure 1Com parison of prey com position for pitchers with intact
and with grazed-down rim hairs (box plot; rim condition: m inus
sign, grazed down; plus sign, intact). The prey groups ‘ants’ and
‘other prey’ (right) are presented on an extended scale. For
statistical analysis, we used the non-param etric Mann–Whitney
U -test. There is a significant difference in the num ber of term ites
(P?0.02), but no significant difference for the prey-group ants.
The difference in the num ber of the group ‘other prey’ was signifi-
cant (P?0.02) but in our opinion this was too heterogeneous to
allow any conclusions to be drawn. Details are available from the
authors. Plus signs, m axim um values; hollow squares, m edians;
error bars, lim its; green boxes, 25th to 75th percentiles.
© 2002 Macmillan Magazines Ltd
marginatafor one prey taxon, unique so far
among carnivorous plants.
The main attractant for insect prey (ants
are most common1–3) in most Nepenthes
species is its nectar, which may be associated
with a distinctive pitcher colour and smell1.
But N. albomarginata T. LOBB ex LINDL
works differently. If no termites are present,
the harvest diversity looks much the same,
except that the catch is even poorer than in
neighbouring pitcher plants of other species:
a few dozen ants, beetles or flies caught over
the six-month lifespan of the pitcher. How-
ever, termites have frequently been found in
N. albomarginatapitchers, a feature seldom,
if ever, associated with other species3–5.
We studied N. albomarginata in Brunei
and usually found thousands of termites
trapped in a single pitcher (Fig. 1). All ter-
mites in one pitcher belonged to the same
species and were in the same state of decom-
position, suggesting that they were caught
over a short period. We found three termite
genera, all belonging to the subfamily Nasu-
titermitinae, with one genus (Hospitali-
termes) predominating. The feeding by this
termite on live fungal and algal tissue and its
habit of foraging over ground in mass
columns are extraordinary among termites.
N. albomarginata has a unique mor-
phological feature, a rim of living white
trichomes directly below the peristome
(Fig. 2). This had not previously been asso-
ciated with the plants’ feeding habits until
one of us (D.J.M.) noticed that the rim’s hairs
were missing from pitchers that had caught
termites. A comparison of large numbers of
pitchers over a prolonged period confirmed
the correlation. For several days, nothing
would happen, then — after a single night —
pitchers would fill with termites and their
rim hairs would disappear.
To investigate this, we placed fresh intact
pitchers, together with pitchers with their
white rims removed, near to the head of for-
aging columns of the termite Hospitalitermes
bicolor. When single leading workers came
into direct contact with the white rim hairs,
they turned back to the column and recruit-
ed their nestmates, which began grazing on
the rim and forming food pellets from the
white trichomes (Fig. 2). While doing this,
the termites fell into the pitchers in their
masses, workers and accompanying soldiers
alike. Once in the pitcher, they were unable
to grip the peristome to climb out. Observa-
tion of one grazing H. bicolor column
revealed that up to 22 individuals per
minute were falling into the pitchers, but the
capture rate could easily exceed this for
denser columns. Outside the pitcher traps,
the termites at the column head displayed
typical foraging and recruitment behav-
iour6,7. After about an hour, the hairs were
all gone and the pitcher was evidently no
longer attractive to termites (and was filled
with termites trying to escape).
We do not know how the trichomes lure
termites onto the plant. No long-range
olfactory attraction could be detected dur-
ing our experiments; all contacts seemed to
happen by chance, with termites often miss-
ing pitchers less than 1 cm away from them.
Prey specialization has been proposed for
some Nepenthesspecies3but, to our knowl-
edge, N. albomarginata is the first example
of a carnivorous plant in which this has been
confirmed and functionally described, as
well as being the only species to offer its
tissue as a bait.
Marlis A. Merbach*, Dennis J. Merbach*,
Ulrich Maschwitz*, Webber E. Booth†,
Brigitte Fiala‡, Georg Zizka§
*Fachbereich Biologie, Zoologisches Institut, Johann
Wolfgang Goethe-Universität, Frankfurt am Main,
Postfach 111932, 60054 Frankfurt, Germany
†Biology Department, Universiti Brunei
Darussalam, Brunei Darussalam, Borneo
‡Universität Würzburg, Zoologie III, Biozentrum,
Am Hubland, 97074 Würzburg, Germany
§Botanik/Paläobotanik, Johann Wolfgang Goethe-
Universität und Forschungsinstitut Senckenberg,
60325 Frankfurt am Main, Germany
1. Moran, J. A. J. Ecol. 84, 515–525 (1996).
2. Moran, J. A., Booth, W. E. & Charles, J. K. Ann. Bot. 83,
3. Kato, M., Hotta, M., Tamin, R. & Itino, T. Trop. Zool. 6,
4. Clarke, C. M. Nepenthes of Borneo(Natural History
Publications (Borneo), Kota Kinabalu, Sabah, Malaysia, 1997).
5. Adam-Jumaat, H. Pertanika J. Trop. Agric. Sci. 20,
6. Jones, D. T. & Gathorne-Hardy, F. Insectes Soc. 42,
7. Miura, T. & Matsumoto, T. Insectes Soc. 44, 267–275 (1998).
Competing financial interests: declared none.
NATURE | VOL 415| 3 JANUARY 2002| www.nature.com
Did Nile flooding sink
two ancient cities?
Alexandria, Egypt) stirred worldwide atten-
tion when it was first announced in the
summer of 2000. Their disappearance some
1,250 years ago has been ascribed by Stan-
ley, Goddio and Schnepp1to a strong Nile
flood that caused riverbank failure and the
destruction of the two cities, rather than to
the action of earthquakes, as was first
proposed when the ruins were discovered2,3.
But I believe that this interpretation is
flawed, because no flood could have
reached the Abu Qir Bay at the time of the
disappearance of the two cities, as the
Canopic branch of the Nile, along whose
banks they were situated, had dried to a
trickle more than 200 years earlier.
This consideration seems to have been
overlooked by Stanley et al., who assume
that the Canopic remained active until late
in the first millennium. Toussoun, who is
cited as the main reference for that assump-
tion, is clear on this point: on pages 195–196
of his work4, he gives evidence that the
Canopic silted up gradually during the fifth
century and that it stopped flowing into the
bay long before the Arab armies reached
Alexandria; he found no mention of it in
any of the accounts of the Arab historians.
The radiocarbon ages given by Stanley et
al. for the mud “immediately beneath the
ruins” confirm this view: none is younger
than AD 322. I know of no mention of this
branch of the delta past the fifth century AD,
neither is there any evidence of it on the
maps prepared by Napoleon’s savants in the
Even if we accept the authors’ assump-
tion that the Canopic was still active at the
time of the disappearance of Eastern Cano-
pus and Herakleion, it is unlikely that the
destruction of these two cities would have
been brought about so suddenly. There is no
mention of such a cataclysmic event in any
of the texts written around this period, nor
of the destruction of any other city along the
length of the Nile.
The flood in AD 741/742 was not likely to
have been dangerous or destructive. For
those who know the Nile and the history of
its use, floods associated with higher water
levels than normal were welcome events.
Before the system of perennial irrigation was
introduced in the nineteenth century, the
lowlands of the flood plain of the river were
left fallow during the flood season in readi-
ness to receive the waters of the flood and to
give rise to a larger tract of arable land.
The disastrous floods dreaded in those
he discovery of the two cities of Herak-
leion and East Canopus under the
waters of the Bay of Abu Qir (east of
Figure 2 A pitcher of Nepenthes albom arginatabeing visited by
term ites. Nasuti term ite workers and soldiers are harvesting the
white rim hairs, which m ay m im ic the appearance of term ites’
food. As the insects lose their grip on the peristom e, hundreds or
even thousands fall into the pitcher, where they are trapped.
© 2002 Macmillan Magazines Ltd