1..

OPHELIA 30 (1): 1-19 (March 1989)
aglc gamlcea: Am-
.........
1
L.) off the
FEEDING BIOLOGY OF THE MESOPELAGIC
GAMMARIDEAN AMPHIPOD
PARANDANIA BOECKI (STEBBING, 1888)
(CRUSTACEA: AMPHIPODA: STEGOCEPHALIDAE)
FROM THE ATLANTIC OCEAN
......... 21
win (Cru-
......... 35
ux, 1830)
......... 47
rm(Dalytes on the
......... 55
,
P. G. Moore] & P. S. Rainbow 2
/1 Cf 8 ~
lUniversity Marine Biological Station, Millport, Isle ofCumbrae, Scotland KA28 OEG
2Centre for Research in Aquatic Biology, School of Biological Sciences, Queen Mary College,
Mile End Road, London EI 4NS
rdotea spp.
......... 63
ymbiotic
ABSTRACT
····e·
75
........
95
The mouthparts of the mesopelagic stegocephalid amphipod Parandania boecki (Stebbing, 1888) are
described in detail and fully illustrated. In a staged encounter with the medusaAtolla parva, P. boecki
fed, gripping the edge of the medusa's bell with its thoracopods and held its first antennae aloft,.
bringing callynophores to face anteriorly. The amphipod also seemed to ~ce:pt a dead fish as possi~
ble foo.1. A porphyrin isolated from the stornach contents of P. boecki was identical to protoporphyrin fromAtolla parva. The stornach contents of the amphipod consisted mostly oflarge pieces of soft
tissue (some darldy pigmented) from which nematocysts consistent with those found in A. parva
were identified. In addition, c.rustacean and chiJ.etognath fril.g~ents (but no sand grains) were also
found. Fe-rich crystals in the ventral gut caeca of P. boecki are identical with others in Stegocephaloides
christianiensis shown e1sewhere by the authors to be made offerritin. The concentration ofFe, Cu,
Zn and Cd was assessed in P. boecki and a range of medusae. Atolla parva had a higher Fe concentration than the other medusae. If A. parva is the principal prey item of P. boecki, this may account for
the amphipods' possessing crystals. We presume the crystals are excreted ultimately and thus that
Fe accumulation is limited. The high Cd levels in P. boecki are similar to those in mesopelagic decapod Crustacea. The ~.c>!E~.'?Jogica1,<l<:!.il.P!.iltion~of.t.h.e.~o\l~~parts
of P. boeckibears!riIs.il1,gE~s!,:~:
blancetQtho.§.ege§.cribed as characteristic of certain carrion-feeding lysianassids.
lsease m
,f the epixe ..... 113
,rval asci........ 131
>rawn Pa........ 141
ignopholas
. . . ...
"
155
rributions
rvation. 187
INTRODUCTION
eakdown
....e·
The biology of the marine amphipod family Stegocephalidae is litde known.
Most of its members are bathyal or abyssal (Barnard 1969) and, in most cases,
only a limited literature - mainly concerned with systematics - exists. One exception is the work of the authors (Moore 1979, Moore & Rainbow 1984) on the
small species Stegocephaloides christianiensis Boeck from British coastal waters. It
was proposed that S. christianiensis, and some other stegocephalids, are fast-swimming predators feeding on benthic coelenterates and evidence was presented to
199
tea baltica
........ 213
rcinophila
coast .. 225
r
OI
~)
!
! '
c,
~~:
V u
\.
....
( t!-. ;'( '.
j
:}
}'
"';-""'_'
.-
.'
2
'V"
P. G. MOORE & P. S. RAINBOW
support the view that S. christianiensis feeds on the soft tissues of the sea-pen Pennatula phosphorea. U nusual octahedral crystals in the gut caeca cells ofS. christianiensis
proved to consist of ferritin. These iron-rich crystals could be excreted from the
caeca and voided in the faeces. Coelenterate tissue from potential prey species
was shown to have a high iron concentration and crystal formation and expulsion
by the amphipod was regarded as a physiological adaptation for dealing with an
iron-rich food supply.
Parandania boecki is characteristic of mesopelagic depths (usually 550-960 m but
extending to 2200 m) in the Atlantic and Pacific Oceans (Birstein & Vinogradov
1958, 1970, Barnard 1961, 1964 and unpubl., Gurjanova 1962, Thurston 1976).
Museum material of this species had been investigated for caecal crystals by
Moore & Rainbow (1984). In that paper, the authors described finding iron-rich
octahedral crystals (height 6.60 ± 2.39 x breadth 4.04 ± 0.83 (S.D.) pom) in the
caecal cells of P. boecki.
Recently, it proved possible to !!l2:~stigate the feeding biolo~ of P. boecki in
more detail, involving a) behavioural observations, b) microscopical examination both of the amphipods' gut contents and of potential prey and c) chemical
analyses ofamphipods and possible food items. These approaches havebeen supplemented by transmission electron microscopy ofthe gut caeca, and an elucidation of the functional morphology of the mouthparts has been achieved by disseetion and scanning electron microscopy. The results of these investigations are
described below.
Table 1. Details,
sae, either i) fre
P.S.R. wishes to thank the officers and crews of R.R.S. 'Discovery' on cruises 156 and 168 and is
grateful to the Central Research Fund of the University of London and Professor E. A. Bevan
(Queen Mary College) for travel funds in 1985, and NERC (Grant GR3/6485A) for financial assistance in 1987. We are very grateful to Dr P. J. Herring (Lo.S.) for his considerable assistance as
principal scientist on cruise 168, for provision of voucher material of medusae, and for reading and
criticizing an earlier draft of the manuscript; to Mr H. S. J. Roe, principal scientist on cruise 156
and for identifying copepods; to Miss K. Chidgey for identification of chaetognaths; to Professor
R. Bonnett (QM.C.) for assistance and advice on porphyrins; to Mr C. Arneson for photography
on board the 'Discovery'; to Dr L. Tetley and Mrs M. Mullins (Glasgow University) for assistance
with scanning electron microscopy; to Mr K. Pell (QM.C.) for transmission electron microscopy;
to Dr Valerie Smith (Millport) for kindly allowing us access to her photornicroscope and to Mrs C.
Lafferty for photography.
alive, were I
deep frozen (
of various pe
stored in 70
glutaraldehy
2h, room ter
room temp.)
sis), dehydra
transmission
ide, embedd
ultramicroto
stemEDXeJ
urany.ta
tioned• . 5
scanning elecoated with ~
SEM.
Analysis 0
shore-based
MATERIALS & METHODS
Animals were collected (see Table 1 fordetails) in the North East Atlantic between
34q,47°N, 12q,22°W either duringJuly 1985 (RRS 'Discovery' cruise no. 156) or
duringJuly and August 1987 (RRS 'Discovery' cruise no. 168), using a rectangular midwater trawl (8 m 2 mouth area, mesh size 4.5 mm), with a elosing cod-end
which kept contents at a temperature elose to that of the collection depth (Wild
et al. 1985). Specimens of P. boecki and medusae in good condition, invariably
...
Date
Le,
a) Parandania bo.
23.7.85
34'
23.7.85
35'
23.7.85
35'
24.7.87
24.7.87
25.7.87
25.7.87
1.8.87
2.8.87
35'
35
35
35
40'
41
b) Medusae
i) Frozen
27.7.87
37'
2.8.87
41'
5.8.87.47
ii) FJ!!!Irfer
27.7.87
37
2.8.87
41
t
I
3
FEEDING IN PARANDANIA
a-pen Pennatchristianiensis
ted from the
prey speCles
nd expulsion
'aling with an
50-960 m but
Vinogradov
urston 1976).
crystals by
ing iron-rich
.) Jtm) in the
f P boecki in
'cal examinad c) chemical
aveb~sup­
dar~cida­
ved by dissecstigations are
6 and 168 and is
SOI" E. A. Bevan
I fOI" financial aslble assistance as
:I fOI" I"eading and
tist on cruise 156
lths; to Professor
for photography
ty) for assistance
tron microscopy;
pe and to Mrs C.
antic.4Ittween
ise no. 156) or
19 a rectanguosing cod-end
1 depth (Wild
m, invariably
Table 1. Details ofcolIection fI"om NE Atlantic ofa) all Parandania boecki taken and b) selected medusae, either i) frozen for metal analysis OI" ii) fixed in 10 % formalin fOI" inspection of nematocysts.
Location
No.
Time (GMT)
Depth
a) Parandania boecki
34°N22°W
23.7.85
35°N22°W
23.7.85
35°N21°W
23.7.85
9:20-10:20 (DAY)
12:49-13:29 (DAY)
20:48-21:48 (NIGHT)
870-1100 m
1040-1300 m
590- 800 m
2
1
1
35°NI3°W
35°NI3°W
35°NI4°W
35°NI4°W
40 oN21°W
41°N20oW
14:16-16:17 (DAY)
20:25-21:29 (NIGHT)
10:29-12:29 (DAY)
15:59-17:59 (DAY)
15:12-17:12 (DAY)
11:40-13:40 (DAY)
660- 800 m
825-1010 m
720- 860 m
720- 865 m
685- 790 m
1000-1200 m
1
1
Date
24.7.87
24.7.87
25.7.87
25.7.87
1.8.87
2.8.87
1
2
1
3
i1~
b) Medusae
i) Frozen
37°NI4°W
27.7.87
41°N20oW
2.8.87
11:40-14:40 (DAY)
11 :40-13:40 (DAY)
1250-1500 m
1000-1200 m
47°NI2°W
11:01-14:01 (DAY)
835- 980 m
ii) Fixed fOI" nematocysts
37°N14°W
11:40-14:40 (DAY)
27.7:87
41°N20oW
11:40-13:40 (DAY)
2.8.87
1250-1500 m
1000-1200 m
5.8.87
9 x Atolla parva
4 x Atolla wyvillei
1 x Atolla parva
5 x Periphylla periphylla
3 x Atolla parva
2 x Atolla parva
1 x Atolla wyvillei
alive, were placed individually in snap-seal polythene bags and immediately
deep frozen (-20°C), or used for laboratory experiments or dissected for fixation
ofvarious parts. For light microscopy, tissues were fixed in 10% formalin and
stored in 70% ethanol. For electron microscopy, tissues were fixed in 4%
glutaraldehyde (2h, room temp.), washed in sodium cacodylate buffer (pH 7.3,
2h, room temp.), stained in 1% osmium tetroxide in Na cacodylate buffer (2h,
room temp.) (Note: this step omitted in tissues destined for X-ray micro-analysis), dehydrated through 30% and 70% alcohol and stored in 70% alcohol. For
transmission electron microscopy (TEM) tissues were cleared in propylene oxide, embedded in TAAB resin, sectioned at 0.5 Jtm or 40 nm on a Huxley MkII
ultramicrotome and examined in aJeol 100C T.E.M. equipped with Link system EDX energy dispersive X-ray microanalyser, with and without staining in
uranyl acetate - lead citrate. Alcohol-fixed material was also embedded, sectioned at 0.5 Jtm or 70 nm and similarly examined with and without staining. For
scanning electron microscopy of mouthparts, material was critical point dried,
coated with gold in a Polaron E5000 sputter coater and examined in a Philips 500
SEM.
Analysis ofheavy metals was undertaken on animals transported frozen to the
shore-based laboratory. These animals were thawed, oven dried to constant
p
4
P. G. MOORE & P. S. RAINBOW
weight (60°C) in preweighed acid-washed Pyrex test tubes, digested in conc.
HN0 3(Aristar grade, BDH Ltd) at 100°C with a glass pear for reflux, made up
to volume with double distilled water and analysed for Fe, Cu, Zn and Cd using
a Varian AA 375 atomic absorption spectrophotometer with flame atomization
and background correction as appropriate.
The test for porphyrin compounds, whose main sources in the mesopelagic
zone are scyphomedusae, particularly the genus Atolla (Dr P. J. Herring 1987,
pers. comm.), was carried out at sea both on tissues of A. parva and on the
stomach contents of P. boecki. Concentrated sulphuric acid and methanol (1: 10
v/v) were added to the sampies, forming methyl esters ofany porphyrins present,
which were detected by their red fluorescence under long-wavelength (- 365
nm) U/V illumination. In the laboratory, extracts of P. boeckz' gut contents and of
A. parva (standards), which had been stored in the dark, were run separatelyon
thin layer chromatograms in order to compare the elution positions of the
methylated porphyrins in each sampie.
R.Mnd
0&~
Q~:i
RESULTS
Description 0] the mouthparts
rif P.
Although Stebbing (1888) provided an extensive deseription ofthe mouthparts
of P. boeckz', he omitted mention of several significant features and did not comment on the functional arrangement of these structures. The following diagnosis
(see Figs 1 & 2) builds on and extends his description and pertains to a 16 mm female. The functional aspects offood handling are considered in a later section.
Epistome cowl-like (Fig. 2B), carinate along mid-line, gibbous proximally;
upper lip (labrum) small, weakly bilobate and slightly asymmetrical (Fig. 1);
mandibles broad thin curved sheets, prominently prognathous extending the
cowl-shape of the epistome ventrally (Fig. 2B), each mandible cut away at anterodistal corner to accommodate the posterior support wedge of the upper lip;
incisor ofleft mandible slightly overlapping right; incisor cutting edge simple,
nearly straight, posterodistal angle rounded but with minute tooth, anterodistal
angle alated; right incisor with sub-distal, concave, crescentic pad (Fig. 1)
formed from irregular 'honeycomb' callosities (strengthening (?)) on medial
base of anterodistal alation, on lateral face in like position, a triangular field of
:,' flimsy, pennant-like scales (Fig. 2H), a row ofperhaps 9 minor teeth notched into
the anterior edge of the alation (Figs 21, J); left incisor with comparable features
less well-developed (see Fig. 2G). Lower lip (labium) without inner lobes; outer
lobes distally setose, forming a deep-throated collar whose posterior medial rim
is fringed with a strong setal row, posterodistal tip of the outer lobe formed into
a prominent tooth-like papilla; mandibular processes short and blunt. The 'deep
collar' ofthe inner lip is conformable with the cowl ofthe mandibles. First maxillae strongly muscularized; inner and outer plates coplanar; inner plate obtusely
..
,-
~-
boeckz'
,
,
t
i
f
t
•
I
"
Fig. 1. Mouthparts of
lip; Mnd = MandibJ
FEEDING IN PARANDANIA
5
sted in conc.
ux, made up
and Cd using
e atomization
mesopelagic
erring 1987,
a and on the
ethanol (1: 10
yrins present,
ngth (- 365
ntents and of
separatelyon
sitions of the
e mouthparts
did not coming diagnosis
to a 16 mm fe, later section.
lS proximally;
rical (Fig. 1);
extending the
lt away at anthe upper lip;
~ edge simple,
1, anterodistal
pad (Fig. 1)
?)) on medial
rlgular field of
h notched into
,rabl_tures
~r lob~outer
or medial rim
>e formed into
mt. The 'deep
s. First maxilplate obtusely
Fig. 1. Mouthparts of Parandania boecki (16 mm 9). Abbreviations - UI. = upper lip; L.I. = lower
lip; Mnd = Mandible; MxI = maxilla I; MxII = maxilla II; Mxpd = Maxilliped minus inner
plate; i.p. = inner plate.
.
6
P. G. MOORE & P. S. RAINBOW
Fig. 2. A) Parand.
B) Head of P bo
C) Head ofP boe,
dibles (mnd) and
D) Lateral view (
er lip sealing gap,
dal palp spanning
upper lip, m.p. =
E) Mouthpart bl
second maxilla in
maxilla I palp, L
mouth, b = ma:
F) Stylet-like spir
G) Left mandiblt
subterminal teeth
H) Right mandit
subterminal teeth
~dibl'
I) Right
callosities (c) on rr
J) Subterminal t
" . . ...=.t
sub-triangular bearing 16 strong setose spines along the medial margin; outer
plate reaching beyond inner bearing 9 strong, terminally rugose spines distally
and two separate fields of long slender setae sub-distally to left and right of the
mid-line on the posterior face; palp uniarticulate, orientated at right angles to the
plane of the inner and outer plates, bearing 12 long, sparingly setulose distal setae. Second maxilla strongly muscularized with large proximolateral bulb ac-
commodating (
bearing two ra
longer and mOl
other rank of s
denticulate tOY\
posterior face s'
coplanar with
plates fleshy, tri
especially wellslender setae aJ
2F), anterior m
overread" in
into spat~e s
Fig. 2A illustrat
va (the commo
FEEDING IN PARANDANIA
7
Fig. 2. A) Parandania boecki (16 mm '() in live encounter with the medusa Atolla parva in the shipboard laboratory. Note orientation of first antennae.
B) Head of P boecki. Note cowl-like epistome (e) and broad mandible (m). Scale bar = 1 mm.
C) Head of P boecki 'en face', showing remains offood (f) held between the right (r) and left (I) mandibles (mnd) and right and left maxillipedal palps (mxpd.p); u.1. = upper lip. Scale bar = 50/Lm.
D) Lateral view (Ieft) ofmouthpart bundle of P boecki. Note prominent mandibular process oflower lip sealing gap between base of mandible and first maxillae, also distolateral setae on maxillipedal palp spanning gap between maxilliped and first maxilla. e = epistome, m = mandible, u.1. =
upper lip, m. p. = mandibular process oflower lip, mxI = maxilla I, mxII = maxilla II, mxpd =
maxilliped. Scale bar = 0.2 mm.
E) Mouthpart bundle of P boecki in longitudinal (approx.) seetion, showing in situ orientation of
second maxilla inner plate (ip); op II = maxilla II outer plate, op I = maxilla I outer plate, p =
maxilla I palp, Ll = lower lip, md = mandible, e = epistome, m = approximate position of
mouth, b = maxilliped base, gI & II = gnathopods 1 & 2 (incomplete). Scale bar = 0.5 mm.
F) Stylet-like spine (s) emanating from conical base (cb) from distal face ofinner lobe of maxilliped
of P boecki (see also Fig. 1). Scale bar = 4/Lm.
G) Left mandible of P boeckl; lateral face of anterodistal angle, showing a1ate projection (a) with
subterminal teeth (t) and small field of scale-like structures (s) on 'shoulder' of mandible. Scale bar
= 25/Lm.
H) Right mandible of P boeckl; lateral face of anterodistal angle, showing alate projection (a) with
subterminal teeth (t) and larger field (cf. left mandible) of scale-like structures (s) on shoulder of
mandible. Scale bar = 12.5 /Lm.
I) Right mandible of P boecki anterodistal angle 'en face', showing saddle-shaped concave field of
callosities (c) on medial face, convex field ofscale-like structures (s) on lateral face ofmandibular
'shoulder' and subterminal teeth (t). Scale bar = 25/Lm.
J) Subterminal teeth (t) of anterodistal angle of right mandible of P boecki. Scale bar = 3/Lm.
+-
l--l
'maraouter
I spines distally
ind right of the
ht angles to the
:ulose distal seateral bulb ac-
commodating contracted musculature; inner plate somewhat triangular in shape
bearing two ranks of long setae on mediodistal margin, one crescentic rank of
longer and more setose setae emanating sub-distally from the anterior face, the
other rank of shorter, stronger setae (plumose for the most part, but becoming
denticulate towards the apex of the inner plate) embedded in the distal margin,
posterior face setulose; outer plate narrower, sub-equal in length to the inner and
coplanar with it, bearing 16 distal setae of various lengths. Maxilliped; inner
plates fleshy, triangular in section, fused basally, with honeycomb surface pattern
especially well-developed along lateral margin, distal truncate face bearing two
slender setae and two stylet-like spines emanating from conical bases (Figs 1 &
2F), anterior margin bearing row of strang, sparingly setulose spines; outer plate
overreaching inner, medial margin bearing row oflong setae but none modified
into spatulate spines; palp, 4-articulate, article 4 elongate, lanceolate.
The Jeeding position oJ P b 0 ec k i
Fig. 2A illustrates the position adopted by P boecki in an encounter withAtolla parva (the commonest medusa captured at appropriate depths) in the shipboard
Table 2. The occurrence ofnematocyst types and
'amphora~shapeditems
identified from the stomachs of6 Parandania boeeki in a variety of mesopelagic medusae from the N.E. Atlantic Ocean.
CO
Parandania boeeki stornach contents
nematocyst
capsule shape
approx. size
(/tm)
ovoid
thin rod
sphere
long rod
inflated
e10ngate
'amphora'
17.4-39.1
x
8.7-17.4
34.8-75.2
x
8.7
17.4-26.1
diam.
some <69.6
117.4x8.7
113 x 26
<400 x 113
:0
o
~
o
o
:;0
Medusae
[1j
Atolla wyvillei Haeckel
Atolla parva Russell
+
+
Atolla vanhoeffeni Russell
+
+
+
+
P?
:0
y:>
s:Z
?
+
tel
~
Periphyllina ransoni Russell
+
Periphylla periphylla (Peron & Lesueur)
+
+
Nausithoe atlantiea Broch
+
?
Nausithoe globifera Broch
___ - " . , I " " • • ltttt't.
I fr BI;.
C I
#}
"C:l
e:.
°
::r
-'::l
-g
Cl::
CIl
0
n
0~
~
o-"C:l
..,..,::l"O "0
o UJ ...,
g:Si~
0
....,
~ ~ ~ ~ ~Pl~o-o
~~. ö'
8
0
(t q"C:l 0
'"
t;;.
::r o
_. (1l
o C
~
::l
8"0
~
0
::l ~
Cl..... lli
_.
o
::l
::l
!l!l'
0 P::l;
_
C>l
0
""'::l
::r
UJ::lcOCIQ
o
0
:::::: '"
c
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UJ~UJO
~-~::r::l
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~. ,,-.,
FEEDING IN PARANDANIA
9
laboratory. Note that the upwards flexure of the first antennae (antennules)
brings the aesthetasc brush (callynophore ofLowry 1986) - which emanates from
the posterior face of peduncle article 3 - to an anterior position consistent with its
effective operation as a presumed chemosensory organ. Chemosensation (eg. of
food) would be anticipated to be developed to a high degree in this eyeless amphipod.
The lanceolate form ofthe gnathopodal and peraeopodal dactyli would facilitate a secure, crampon-like grip on such a slippery, pulsating substratum as a
medusa. The gnathopods may also serve to carve the tissues of the medusae,
creating cut edges along which the mouthparts could be worked with greater efficiency.
+
Behavioural observations on P boecki
Two individuals of P boecki were added to a petri dish containing a single Atolla
parva. The amphipods swam very actively around the dish and upon encountering the medusa (which would have been inevitable), each amphipod stationed itself at the edge of the medusa's bell (Fig. 2A). It is not possible to say whether
swimming was directional towards the medusa in such a confined space. Each P.
boecki adopted the same feeding position, ie. with first antennae raised (see
above), and the mouthparts were in contact with the medusa's tissues for several
minutes. Both amphipods were clearly feeding.
When one of the P boecki was added to a dish containing a freshly dead fish (Cydothone sp.), an unidentified moribund decapod crustacean and a live Atolla parva
(all derived from the same hauI), P boecki explored the fish as it didA. parva, showing no particular preference for the medusa. It is impossible to state with certainty whether P. boecki fed on the fish. It ignored the decapod completely.
<"C.
Analysis 01 porphyrins
The gut contents of two live, freshly collected P boecki were tested for porphyrins
on board ship. One gave a strang positive reaction, the other less strong. Pieces
of Atolla parva were consistently positive and were run as standards contemporaneously. At Queen Mary College (courtesy of Professor R. Bonnett), extracts of A. parva and P boecki gut contents - from the strongly positive ship-board
test - were analysed by thin layer chromatography. An exact correspondence of
elution position of the porphyrin esters was found in the two samples, ie. the porphyrin contained in the gut contents offield-collected P boecki was indistinguishable from protoporphyrin isolated from A. parva (Bonnett et al. 1979). This indicates the presence of Atolla material in the amphipod's gut, though this evidence
alone is insufficient to identify A. parva specifically as the main target of the amphipod's feeding.
10
P. G. MOORE & P. S. RAINBOW
Fig. 3. A) Parandania boecki; squash preparation of a ventral caecum, showing octahedral crystals
stained Prussian blue with potassium ferrocyanide (Perl's method for ferric iron). Scale bar = 50
!L m .
B) P boeclci; ferritin crystal in ventral caecal cell. Alcohol fIXed, 70 nm section, stained with uranyl
acetate - lead citrate, 0 = mitochondria. Scale bar = 4 !Lm.
C) P boecki; ferritin crystal (Fe) exceptionally positioned in the nucleus of a ventral caecal cell. AIcohol fIXed, 70 nm section, stained with uranyl acetate - lead citrate; n.m. = nuclear membrane,
c.m. = cell membrane, ehr. = chromatin. Scale bar = 2 !Lm.
D) P boecki; ferritin crystal in ventral caecal cello Alcohol fIXed, 70 nm section, stained with uranyl
acetate -lead citrate. Note: crystal not membrane bound; charaeteristic lattice structure of ferritin
visible. Scale bar = 0.05 !Lm.
E) P boecki; 'calcium granules' (Ca) in ventral caecal cells. Fixed in glutaraldehyde and osmium
tetroxide, 40 nm section, stained with uranyl acetate -lead citrate; m = mitochondrion. Scale bar
= 1 pm.
F) 'Amphora' structure from bell-edge tissue of the medusa Atolla parva. Note: 'top' end invaginated. Scale bar = 50 !Lm.
G) 'Amphora' structure in (F) at higher magnification showing surface scale pattern. Scale bar =
•......
.~~
")~
.... :;,;;~., ~'.c1.f"
•• ~
...'
~ w"."~
....
,:,
~;'~':' :
--
.~."....
A. \- '....
•
".:'''''
..,f
20 !Lm.
H) 'Amphora' identical in form to those in Atolla parva tissues (see F, G), recovered from the
stornach contents of Parandania boecki. Note: surface scale pattern visible towards the top right ofthe
picture. Scale bar = 20 p.m.
....
Gut contents 01 P b0ecki
A variety of items was found in the stomachs of P boecki. In descending order of
prominence, these items were a) pieces of complex musculature, usually with
blobs ofdark pigment and sometimes with tendril-like appendages interpreted as
being pieces of medusa bell, b) amorphous lumps ofdark pigmented tissue, often
revealing nematocysts ofvarious size and shapes when examined microscopically, c) crustacean fragments, including one whole augaptilid copepod, and d)
chaetognath jaws (including one head identifiable as Sagitta macrocephala). No
sand grains or other detrital material were found.
In order to cross-match the nematocysts observed in the amphipod's gut contents with potential prey coelenterates, a variety of voucher medusae was kindly
made available to us by Dr P. J. Herring (1.o.S., Wormley). Table 2 presents the
results of this investigation. It is clear that the best cross-match with the amphipods' gut contents is to be had with Atolla parva. The exact nature of the strange
'amphorae' discovered (Fig. 3F-H) is uncertain. They seem very large to be
nematocysts: there was no evidence of any thread either contained within or expelled without these capsules, yet the wider end was clearly capable of invagination. Their outer surface was covered in minute hair-like scales. Most of these
deep-water medusae are dark in colour (reddish or brownish, see RusseIl1970),
a feature consistent with the darkly pigmented nature of many of the tissue pieces
in the amphipods' guts.
,
t
,
t
f
t
"
,~.:
.
... ., .,.",., .
...
~~.~~~~~'.'
:~"."::
The presence 0
cells of the vent
this species frm
,.
FEEDING IN PARANDANIA
11
tahedral crystals
. Scale bar = 50
ined with uranyl
al caecal cd!. Allear membrane,
ined with uranyl
cture of ferritin
'top' end invagiern. Scale bar
=
overed from the
e top right ofthe
:lding order of
, usually with
interpreted as
:d tissue, often
nicroscopical)epod, and d)
:rocephala). No
pod's gut con,ae was kindly
2 presents the
ith the amphi,of the strange
larato be
with!!"or exe of invaginaIMost of these
IRussell 1970),
le tissue pieces
t
Crystals in the ventral gut caeca 0] P boecki
The presence of single (usually) octahedral, iron-rich crystals (Figs 3A-D & 4) in
cells of the ventral caeca, as previously reported by Moore & Rainbow (1984) for
this species from histological and histochemical examination, was confirmed by
12
P. G. MOORE & P. S. RAINBOW
Parandania boecki
Table 3. The conce:
three sr
Fe
Species
Parandania boecki
crystal
AI
p
AI
p
Atolla parva (whoIe)
Ca
Ca
- (part)
Atolla w~villelrt)
cytoplasm
Periphylla periphylla
Mg
Fig. 4. Spectra ofelemental analyses of octahedral crystals (top) and adjacent cytoplasm (bottom)
in cells from the ventral caeca of Parandania boeckz; vertical scale is an arbitrary number of counts,
horizontal scale is a relative scale ofX-ray energies. The strong Fe peaks are restricted to the crystal. Minor peaks for Mg, P and Ca were also present in the cytoplasm. The strong Al peaks are
artifactual products of the support grid.
ultrastructural studies and X-ray micro-analysis (Figs 3D & 4). Crystals were not
membrane bound. They attained a size of27.9x12.9 p.m (cf. Moore & Rainbow
1984). There can be no doubt that these crystals, like those of S. christianiensis, also
consist of ferritin. In the majority of cases ferritin CrystalS occurred in the
cytoplasm of the cell (as also for S. christiam'ensis), but in a single exceptional case,
a ferritin Crystal was found in the eell nucleus (Fig. 3C).
Other smaller, irregular granules in eells of the ventral eaeea of some individuals were identified by X-ray micro-analysis as ealeium-rieh granules (Fig.
3E), as deseribed also for S. chTistianiensis (Moore & Rainbow 1984). Such ca1cium-rieh granules in Orchestia gammarellus are variably present in ventral eaeeal
t
,t
cells according tc
ation, either assc
unusual absence
Ir
1
Table 3 shows th(
sae Atolla parva, .!
both P. per.la ;
er of magnitude i
eies' small size ar
ing on A. paTva (
predicted would I
We presume th;
Stegocephaloides chi
13
FEEDING IN PARANDANIA
Table 3. The concentration of metals (J.lg g-I dry wt.) in individual amphipods Parandania boecki and
three species of medusae sampled in summer 1987 (n.a. = not analysed).
g
Fe
~~
Cu
~~
Zn
~~
Parandania boecki
0.0080
0.0117
0.0375
0.0128
110
111
44
93.8
21.3
28.5
12.4
20.8
52.5
141
75.1
84.0
n.a.
25.6
38.2
9.1
Atolla parua (whoie)
0.0505
0.0096
0.00440.0072
0.0092
0.0057
0.0038
0.0109
0.0238
0.0703
174
117
325
113
491
104
239
488
233
45.5
7.9
16.7
50.0
26.9
19.6
31.6
42.1
33.6
15.4
2.8
25.7
20.8
40.9
16.7
22.8
67.8
18.4
57.3
48.3
42.7
0.99
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
13.8
13.3
8.5
Atolla wyuillei (part)
0.0135
0.0828
0.2096
1.3873
20
14.5
10.5
9.4
7.4
4.8
3.8
4.9
11.1
13.3
13.4
12.6
6.2
1.8
2.1
3.1
Periphylla periphylla
0.8141
0.9128
0.4950
1.3352
0.6203
17.2
14.5
20.7
12.7
16.5
7.4
6.3
6.3
5.6
4.8
24.6
36.4
55.6
30.0
34.2
2.8
2.1
4.5
3.2
2.0
Dry wt
Species
al
- (part)
rasm
)plasm (bottom)
1mber of counts,
icted to the crys·
mg Al peaks are
fstals were not
re & Rainbow
~tianiensis, also
the
reptional case,
curr.
of some indigranules (Fig.
i). Such calciventral caecal
t
ceHs according to the stage of the moult cyde (see Meyran et al. 1986). Such variation, either associated with moulting or feeding cydes, may also account for the
unusual absence of ferritin crystals in occasional individuals sectioned.
Iran and other metals in P. boecki and certain medusae
Table 3 shows the concentrations ofFe, Cu, Zn and Cd in P. boecki and the medusae Atolla parva, A. wyvillei and Periphylla periphylla. The concentration of iron in
both P. periphylla andA. wyvillei was substantially lower than inA. parva. The order of magnitude increase in Fe in A. parva may weH be assoc'iated with that species' small size and hence relatively large surface area for iron adsorption. Feeding on A. parva could weH represent the iran challenge to P. boecki which we
predicted would be met with a ferritin crystal elaboration and expulsion system.
We presume that the amphipod ultimately expels its ferritin crystals (like
Stegocephaloides christianiensis): we have not proven this condusively. However,
.
14
P. G. MOORE & P. S. RAINBOW
certain sections (which unfortunately were ofinsufficient quality for photographic reproduction) were suggestive of the breakdown of the distal region of cells
bearing a ferritin crystal. Such degeneration (apocrine secretion?) would liberate
crystals into the caecallumen.
direct observati(
also possible tha
could be detacht
(inner plates; p;
palp, again a far
ticles plays no e~
fragments ofcor
stomachs of P b(
may not limit th
muscularized m
compress and p;
Functional morphology ofmouthparts of P. boecki
The mouthparts of P. boeeki are noticeably specialized fordeaJj.n-Z.'YÜ!!§gfLJle.§p:y
greatly
developed into long, smooth cutting
(Fig.
fooel. The }ncisonv~re
." ._---;(
..
-- - blades
._- ..1), and the cC)ßcave corpora mandibul,\e,. result in a cowl-~hape.~ mandibular
scoop, accommodating alarge bitten mot~el (Fig. 2B). The labrum forms a positioning chock keying the mandibles (ie. it is not 'folded back' in the manner
described by Stebbing (1888) whose observation must have been on a contorted
specimen). The massively developed epistome would receive structural reinforcement from its carinate gibbous form and is weIl developed to transmit strong
arcuate forces to the mandibles during any posteroventral rotation of the head.
Such a head movement incorporating posteriorly gaping incisors (their anterodistal corners may be keyed together by their alate teeth and crescentic pads)
applied against a soft substratum would produce a surface shaving or gouging effect which would be especially effective if applied along a ridge of exposed tissue.
Concentration of feeding at suitable edges might be achieved by initial choice of
feeding site (Fig. 2A) or by primary disruption of tissues by the gnathopods (or
both).
The unique micromorphology of the incisors reported above has, as yet, no
functional interpretation. The lack of a well-developed molar spine row for gripping food is, we presume, more than compensated for by the large, anteromedially directed setae bordering the anteromediaIly-angled inner plates of the first
and second maxillae (Figs 1 & 2E). These long setae from left and right sides (Fig.
2E) could form a 'creel eye' through which food pieces could easily be pushed anteriorly into the mouth, but which would effectively prevent movement in the
reverse direction (cf. also Broyer & Thurston 1987 on Alieella gigantea). Large
pieces offood would be forced dorsally towards the mouth, mostly likely by compressive forces produced by the anterior rotation ofthe maxillipeds transmitted
via their wedge-like, basally fused and reinforced inner plates (Fig. 1) which marry snugly into the V -shaped furrow between the left and right maxillary inner
plates. The la,ck of mandibular IIloJa,.r.s.. {<.t.J~!!!i!L<;.h~.!!'!:.~!e.I;'!~!~1.p.!.~.~1l.l.g!;~_9,ny
t!:Ü.l.l.!~tiQJ}.<?ff()<:>(t Indeed we have found that P. boee1ci ingests food fragments at
least as broad as the space between the labial lobes. It is possibly noteworthy that
the diamond-shaped section of the mouth gape and of one food fragment recovered in situ both had side lengths which matched the blade length of the incisors
which could suggest that a single mouthful might be detached by taking two juxtaposed bites. The exact mechanism ofbiting, however, is likely always to elude
.
~-
~
•
•
All present indic
concerning the li
Barnard 1961) ar
ferritin c~s.
cifically a . u t
phorae'); second
the laboratory; t
tribute of Atolla s
contents of P bo
boeeki (see Introd
nent is that A. pa
other mesopelag
size and hence I
hedral crystals in
appearance and
(1984) establishet
of ferritin. The r
grains in its st(
Stegoeephaloides eh
The morpholo
striking resemblc
certain ca-an-fc
that this sdW'tra
a non-triturative
mained unnotice
ly detailed. Most
result ofcompres:
three-dimension;
FEEDING IN PARANDANIA
direct observation because of the head's concealment by the anterior coxae. It is
also possible that strips or pieces of soft tissue larger than the mouth dimensions
could be detached and stuffed through the mouth aperture using the maxillipeds
(inner plates; palps may assist in this too). Certainly the lack of a mandibular
palp, again a family diagnostic character, would suggest that handling small particles plays no essential part of these species' feeding repertoire. That some food
fragments ofconsiderable size, when unfolded, were recovered from the dissected
stomachs of P boecki lends further weight to the view that mouth dimension alone
may not limit the geometry of ingested fragments of such soft tissues. The highly
muscularized maxillae ofthis species (Fig. 1) may be associated with an ability to
compress and pack flexible materials through the mouth.
r photographegion of cells
ould liberate
ith soft, fleshy
g blades (Fig.
d mandibular
forms a posin the manner
n a contorted
ructural reinansmit strong
n of the head.
ors (their anescentic pads)
orgeAngefxpos~issue.
itial choice of
nathopods (or
as, as yet, no
e row for grip~, anteromediI
~tes of the first
ight sides (Fig.
be pushed anIvement in the
igantea). Large
likely by comds transmitted
1) which marlaxillary inner
. precl~s any
dfral'ntsat
bteworthy that
~ragment recol of the incisors
aking two juxu.ways to elude
15
DISCUSSION
I
I
All present indications confirm our earlier hypothesis (Moore & Rainbow 1984)
concerning the likelihood of Parandania boecki being a coelenterate feeder (see also
Barnard 1961) and having an iron expulsion mechanism in its gut caeca based on
ferritin crystals. Firstly, P boecki collected in situ contained recognizable and specifically attributable remains of medusae in their stomachs (nematocysts, 'amphorae'); secondly, P boecki was observed to feed on one medusa (Atolla parva) in
the laboratory; thirdly, protoporphyrin which apparently is a characteristic attribute of Atolla spp. (Dr P. J. Herring 1987, pers. comm.) was detected in the gut
contents of P boecki taken from the field; fourthly the depth distributions of P
boecki (see Introduction) andA. parva (see Russell1970) are coincident. Also pertinent is that A. parva has a significantly higher tissue iran concentration than the
other mesopelagic species of medusae tested, possibly associated with its smaller
size and hence relatively larger surface area for adsorption. Iron-based octahedral crystals in cells of the ventral caeca of P boecki have the same fine-structural
appearance and X-ray dispersion spectrum as those which Moore & Rainbow
(1984) established by X-ray diffraction in Stegocephaloides christianiensis to be made
of ferritin. The pelagic habitus of P boecki is further reflected in the lack of sand
grains in its stomach contents, compared with an epibenthic species like
Stegocephaloides christianiensis (Moore & Rainbow 1984).
The morphological adaptations ofthe mouthparts in this stegocephalid bear a
striking resemblance to those described by Sainte-Marie (1984) as characterizing
certain carrion-feeding lysianassid amphipods. We agre~ with his proposition
that this set oftraits (broad shea.!il1gjI1<::is()r~itl1'<:Q.I!f.~Y~c()rpusIJl4I1gil:>J!1'!C:;_4J1Q
a non-triturative molilr)!llay be more widespread in the Amphipoda, but have remained unnoticed because drawings or descriptions of mandibles are often poorly detailed. Most important is that illustrations of mandibles usually suffer as a
result ofcompression into_one plane (under a coverslip), effectively destroying the
three-dimensional configuration of the part. Species with mandibles of such a
16
P. G. MOORE & P. S. RAINBOW
form as herein deseribed have 1Potentialfc:>r_~~tin.g=9jIlarge pieees of food; also
by ~E.IIl!QatiI].ßthe ehewing proeess and aetively funnelling food into the gut the
ingestion offood is hastened (Sainte-Marie 1984). Couple this with the already
noted (Moore & Rainbow 1984) voluminous stomaeh of P. boecki (presently eonfirmed) and one has the ideal feeding apparatus for a predator eapable of swimming fast and rapidly exploiting an unpredietable supply of soft-tissued food,
whether it be small medusae in the mesopelagie realm (as here), or ephemeral
benthie earrion (in the ease of the speeies studied by Thurston 1979, SainteMarie 1984 and Broyer & Thurston 1987).
Although eoelenterate tissues were a eonsistent feature of the stomaeh eontents
of P. boecki) other identifiable items also oeeurred. Most notably these included
erustaeean fragments, including a whole augaptilid eopepod, pieees of unidentifiable muscle tissue - often darkly pigmented, and ehaetognath fragments
(some attributable to Sagitta macrocephala). Several possible explanations ean be
advaneed to aeeount for these observations, a) that P. boecki is naturally eapable
of eapturing and feeding on a wider variety of prey items than just medusae, b)
that P. boecki ean steal prey items already immobilized by medusae, e) that whilst
ingesting medusae tissues P. boecki might inadvertently eonsume material already
ingested by the medusa, or d) that in the eonfines ofthe eapture-net eod-end for
up to 3h, an aetive predator like P. boecki) eneountering potential prey items at an
unnaturally high density, might gorge on an unusual seleetion of organisms immediately prior to net hauling. None of these possibilities ean be excluded eategorieally on the basis of present data. It should be reealled, however, that in the
laboratory, P. boecki.§.hQwed keen interest in a deadJi~hllQ.j.Lf!lE.Y.JtotJ~ed e~clu­
.sively .on medusae. Also noteworthy is the report by Sainte-Marie & Lamarehe
(1985), that whilst eod-end feeding appeared not to be a major problem in the lysianassid genus Anorryx (being restrieted to a few individuals more than 17 mm
long), when it did oecur, it was with ealanoid eopepods that the amphipods
gorged themselves. It seems most likely, however, that had sueh frenzied eod-end
feeding oeeurred during the eollection of P. boecki (whieh were about 17 mm in
length), many more items would have been reeovered from eaeh amphipod
stomaeh than in faet was the ease.
Most of what we have found in the stomaehs of P. boecki ean be explained by aeeepting that its primary feeding eneounter is with medusae - perhaps espeeially
with Atolla parva - with other organisms only being ingested ineidentally.
The eoneentration of Fe in P. boecki is lower than that reported by Moore &
Rainbow (1984) as eharaeterizing a range of inshore arnphipod speeies: presumably related both to the expeeted decline in available Fe eoneentrations in oeeanie
vs coastal waters and to the large size of Parandania) redueing the eontribution of
surfaee adsorbed iron to the total body eoneentration (Rainbow & Moore 1986).
Moreover the very presenee of an iron exeretory meehanism would lower any aeeumulated iron eoneentration of P. boecki. The coastal amphipod speeies analysed
•
•
earlier do not al
a ferritin-based
haneed Fe eone·
eontained less I
Rainbow (1984)
It seems more li:
mily Stegoeeph;
eess dietary iro
proeessed via a
Same eomme
this juneture. In
eopper in P. boe,
eient to allow fOl
eatalysis. The p<
Rainbow (1987)
needs. The eone
found by Rainb,
Millport, ie. 1.9
to have hi_ac
the deeapod Syst
ived from dietar
animallongevit;
identified as the
a relatively high
vestigated.
Clearly, furth,
this enigmatie aI
in whieh ferritin
importanee ofa 1
biology of its tri'
,
I
Barnard, J. L., 1961
Rep. 5: 23• .
Barnard, J. lWJ64
Sei. 18: 315-335.
Barnard, J. L., 1969
natn. Mus. 271:
Birstein, Ya. A. & M
north-western pa]
(In Russian).
"
FEEDING IN PARANDANIA
es of food; also
nto the gut the
ith the already
presently conpable of swimt-tissued food,
, or ephemeral
1979, Sainte-
mach contents
these included
ces of unidenath fragments
nations can be
turally capable
st medusae, b)
e, c) that whilst
aterial already
etc.endfor
rey Items at an
orgamsms Imexcluded caterver, that in the
not feed excluie & Lamarche
üblem in the lyIre than 17 mm
the amphipods
enzied cod-end
,bout 17 mm in
:ach amphipod
:xplained by ac-haps especially
dentally.
~~i::.S:~:
~
ions in oceanic
contribution of
Moore 1986).
ld lower any ac:pecies analysed
I•
17
earlier do not apparently feed on diets rich in available iron and do not resort to
a ferritin-based, iron expulsion system. Atolla parva, although exhibiting enhanced Fe concentrations compared with other deep-water medusae analysed,
contained less Fe than the Fe-rich coastal coelenterates analysed by Moore &
Rainbow (1984). It is possible that the iron inA. parva is particularly bioavailable.
It seems more likely, however, that as a result of the evolutionary history of the family Stegocephalidae, involving exploitation of strongly iron-rich diets, anyexcess dietary iron (however little) now assimilated by extant stegocephalids is
processed via a ferritin expulsion system.
Some comments on the status of the other metals analysed are appropriate at
this juncture. Intriguingly for a potentially active swimmer, the concentration of
copper in P boecki, following White & Rainbow's proposition (1985), is insufficient to allow for haemocyanin production and may only be enough for enzymic
catalysis. The possibility ofCu deficiency in the deep ocean is noted by White &
Rainbow (1987). Enough zinc, however, is present to underwrite theoretical
needs. The concentration ofcadmium in P boecki is considerably higher than that
found by Rainbow & White (unpublished) in littoral Echinogammarus pirloti from
Millport, ie. 1.91±O.46 p.g Cd g.l dry wt. Many mesopelagic crustaceans appear
to have high cadmium concentrations compared with coastal counterparts, ego
the decapod Systellaspis debilis studied by White & Rainbow (1987), possibly derived from dietary sources (Ridout et al. 1985) or possibly involving variations in
animallongevity. It is of interest to note that Atolla parva, which present work has
identified as the likely dietary focus for P boecki, in addition to high iron also had
a relatively high cadmium concentration compared with the other medusae investigated.
Clearly, further comparative work on the feeding biology of other members of
this enigmatic amphipod family is much to be desired, especially on those species
in which ferritin crystals are reportedly absent. In conclusion, we emphasize the
importance of a knowledge ofa species' natural history in the interpretation of the
biology of its trace metal composition.
REFERENCES
Barnard, J. L., 1961. Gammaridean Amphipoda from depths of 400 to 6000 meters. - Galathea
Rep. 5: 23-128.
Barnard, J. L., 1964. Some bathyal Paeifie Amphipoda eolleeted by the U.S.S. Albatross. - Pacif.
Sei. 18: 315-335.
Barnard, J. L., 1969. The families and genera of marine gammaridean Amphipoda. - BuH. U.S.
natn. Mus. 271: 1-535.
Birstein, Ya. A. & M. E. Vinogradov, 1958. Pelagie gammarids (Amphipoda - Gammaridea) ofthe
north·western part ofthe Paeifie Oeean. - Trudy Inst. okeanol. Akad. nauk SSSR 27: 219-257
(In Russian).
1
18
P. G. MOORE & P. S. RAINBOW
Birstein, Ya. A. & M. E. Vinogradov, 1970. On the fauna of pelagic gammarids in the KurileKamchatka region ofthe Pacific acean. - Trudy Inst. okeanol. Akad. nauk SSSR 86: 4-01-4-19
(English translation: Fauna of Kurile-Kamchatka Trench and its environment, 4-19-4-38. Jerusalern, Israel Program for Scientific Translations, 1972).
Bonnett, R., E. J. Head & P. J. Herring, 1979. Porphyrin pigments of some deep-sea medusae. J. mar. biol. Ass. u.K. 59: 565-573.
Broyer, C. de & M. H. Thurston, 1987. New Atlantic material and redescription ofthe type specimens of the giant abyssal amphipod Alicella gigantea Chevreux (Crustacea). - Zool. Scr. 16:
335-350.
Gurjanova, E., 1962. Bokoplavy sevemoi chasti Tixogo Okeana (Amphipoda - Gammaridea)
chast'1. - Opred. po Faune SSSR, Akad. Nauk SSSR 74: I-HO.
Lowry,]. K., 1986. The callynophore, a eucaridan/peracaridan sensory organ, prevalent among
the Amphipoda (Crustacea). - Zool. Sero 15: 333-349.
Meyran, J.-C., F. Graf & G. Nicaise, 1986. Pulse discharge of calcium through a demineralizing
epithelium in the crustacean Orehestia: ultrastructural cytochemistry and X-ray microanalysis.
- Tissue & Ce1l18: 267-283.
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.
_--- ..
Mr D. Morritt (
1988) he took t'A
of1750-2000m
58; 47°N, 20 0 \A
tained large am(
including, in on,
sp. medusa. Thi
allows us to prec
E. gigantea, in lir.
Rainbow 1984).
e
t
•
!
t
•
,
FEEDING IN PARANDANIA
marids in the Kurileauk SSSR 86: 401-419
·ronment, 419-438. deep-sea medusae. -
f
ption ofthe type speeifeea). - Zool. Sero 16:
poda - Gammaridea)
gan, prevalent among
ugh a demineralizing
X-ray mieroanalysis.
d Stegocephaloides chris-
ephaloides christianiensis
.onal interpretation. -
PhiPowstaeeans. 1985. Coneentrations
frorn the East Atlantie
I
)niversity Press, Carn-
,
i
)ur speeies oflittoral or
ion-feeding lysianassid
ing behaviour. - Sarsia
,Challenger during the
Crustaeea Arnphipoda
H. bio!. Ass. u.K. 56:
\tlantie Oeean. - Mar.
er and zine in molluses
1..
eets in the rnesopelagie
eod e~ystern for the
2: 1583-1589.
19
Note added in press
Mr D. Morritt (Bristol University) has kindly informed us that recently (29 June
1988) he took two specimens of the stegocephalid Euandania gigantea from a depth
of 1750-2000 m in the Atlantic from RRS 'Discovery' (station: Biotrans 11794 #
58; 47°N, 20 o W; gear RMT 8M-3) and that both these animals similarly contained large amounts of deep red (presumed porphyrin-rich) material in the gut
including, in one specimen, an intact seetion ofmarginal ring from a small Atolla
sp. medusa. This observation is in fuH agreement with our hypothesis above, and
aHows us to predict the presence of octahedral ferritin crystals in the gut caeca of
E. gigantea, in line with our earlier report of their presence in E. ingens (Moore &
Rainbow 1984).