STUDIES ON THE LARVAL STAGES OF THE BARNACLES BALANUS CLANDULA
DLTTI
(TTNMETT
MNABIT

DARWIN, 1854, BALANL
NNABULUM (LINNEUS, 1758), CHTHAMALUS

V
ZS POLIMERUS (SOWERBY, 1833).
DALLI PILSBURY, 1916, AND POLLI
BY
JOHN B. SNODGRASS
The Hopkins Marine Station of Stanford University, Pacific Grove, California-
Chthamalus dalli, Balanus glandula, Balanus tintinnabulum, and
Pollicipes polymerus are common barnacles on the coast of Central Cali¬
fornia. All are intertidal species except B. tintinnabulum which lives
continually submerged. Published accounts of larval development in these
species are lacking. It was the purpose of the present study to raise
larvae of each of the species and to describe successive instars suffi¬
ciently to permit identification of each naupliar stage of each species.
Past attempts at in vitro larval cultivation have met with varying degrees of
success. Herz (1933) found eight naupliar stages and one cyprid stage in
in vitro culture of Balanus crenatus. Bassindale (1936) reared Verruca
srosemia to the cypris stage although no settling of the cypris was observed.
Costlow and Bookhout (1957, 1958) successfully raised Balanus amphitrite
denticulata amd Balanus eburneus from hatching to the cypris. Costlow
and Barnes (1961) also raised Balanus balanus to the cypris stage. Moyse
(1933) reared larvae of Balanus balanoides, Elminius modestus, Chtham-
alus stellatus and Lepas anatifera to the cypris stage. Not as suc-
cessful, Sandison (1954) raised several South African barnacle species
only to stage three nauplii. Barnes (1959) and Crisp (1961) managed to raise
3alanus nubilis and Balanus hameri, respectively, to the third naupliar stage
1. Permanent address:



442
22.
John B. Snodgrass - 2
also.
For this study B. glandula was collected on intertidal rocks and
B. tintinnabulum from the underside of an offshore float near the
Hopkins Marine Station of Stanford University, Pacific Grove, California.
polymerus and C. dalli were obtained at Yankee Point, South of
Carmel, California. Mature ovigerous lamellae were removed from the
mantle cavity and placed in fingerbowls containing millipore filtered
seawater. The nauplii that hatched swam immediately toward the lighted
end of the fingerbowl where they were collected in a Pasteur pipette
and transferred to another fingerbowl of millipore filtered sea-
water. This fingerbowl contained Platymonas sp., a flagellate known
to provide a diet on which a våriety of barnacle larvae survive and
grow (Okamoto, 1967). Platymonas was obtained from the Hopkins Marine
Station culture collection. The larvae were cultured at room temp¬
erature (21-23° C). Three to four times daily, samples of each barnacle
species were removed and examined under a compound mocroscope. A few
additional specimens were examined from cultures of nauplii raised on
Platymonas by E. Okamoto at the Hopkins Marine Station.
Three characters which proved most useful in distinguishing
species and instars were antennule setation (Newman, 1965), body
shape, and tail morphology. Two lesser features that proved useful were
the appearance of a separate carapace at stage IV (see Crisp, 1961) in
three of the species examined, and the appearance of a compound eye in
C. dalli in stage Vl. Antennae and mandibular setation were helpful in
identifying certain instars of particular species. Äfter identification
of a particular stage, drawings were made with the aid of a camera luc¬
22
John B..Snodgrass-3
ida. Length measurements were obtained by measuring from the anterior
end to the tip of the tail; in stages IV-VI length from the anterior
tip of the carapace to posterior end was also measured. Set tion of
the appendages was recorded according to the method of Newman (1965).
It was possible to obtain naupliar instars I-IV in B. glandula and
P. polymerus, and to raise C. dalli to thé cypris stage. B..tintinn-
abulum survived only through the third naupliar stage. The results
of the study appear in Figures 1-9 and Tables 1-4. The species studied
show differences in size and body shape, between species and also
between different stages in the same species (Fig. 1, Tables 1-4).
The setation of the antennule proved most useful in separating stages
I-V in C. dalli and at least stages I-IV of the other species (Figs.
1-4, 6-9 ). However, since setation of the antennule was the same for
of species
comparable stages of all four barnacles, identification is dependent
on tail morphology and body shape (Figs. 1, 5 ). Notable features
of the stages of the species studied are discussed below.
Stage I
Size proved to be the only distinguishing feature between the four
species. (Fig. 1, Tables 1-l).
Stage II
At this stage each species attains a characteristic shape (Fig. 1).
C. dalli is shaped much like a heart whose anterior portion is flattened.
The frontolateral horns project at right angles to the body and the
carapace does not yet appear as a separate entity. The body tapers to
a sharp point posteriorly. The tail ends in a prong-like process;
proximally it bears two sharp lateral spines (Fig. 5).
ee
John B. Snodgrass -1
B. glandula has a shield shape with its frontolateral horns
upturned and projecting at approximately 15° from the body; the tail
is long and slender and also ends in a pronged process (Fig. 5).
P. polymerus is shaped like a wine goblet and its frontolateral
horns project at right angles from the body. The tail is much like
that of B. glandula except that it bears small, spiny projections (Fig.
5).
B. tintinnabulum is characterized by its large size, second only
to B. glandula, a rounded body, ahd frontolateral horns which resemble
cattle horns in their positioning. (Fig. 5).
Stage III
In all species this stage'is larger than the preceding one. A new
process appears on the dorsal side of the antennule, immediately prox-
imalto the distal group of four setae. (Figs. 2-4). This was noted
in B. hameri (Crisp, 1961) and in B. nubilis (Barnes, 1959). The tails
increase in size and become jointed above the end prongs in all four
species (Fig. 5 ).
Stage IV
At this stage in B. glandula, P. polymerus, and C. dalli the
carapace becomes markedly differentiated from the main body (Fig. 1).
Also a new process appears on the antennule to make a total of two
which are located proximal to the terminal four (Figs. 2-4, 6-9 ).
As shown in Figure 5 the tails are very characteristic for each species.
These features plus an increase in size make the fourth instar easily
distinguishable from the preceding three.
2
John B. Snodgrass 5
Stage V
In C. dalli there is an increase in size over stage IV and
another seta appears on the dorsal side of the antennule, bringing
the number in the proximal group to three (Fig. 6).
Stage V
The transitions from stage V to stage VI involve no change in
number of setae on the antennule, and size is the simplest, though
not always definite, criterion for distinguishing between the two
stages. Compound eyes have been reported as occurring in the late
stage VI larvae by Costlow and Bookhout (1957). While develop¬
ment of the compound eyes was not followed in C. dalli, larvae of the
same size, both with and without compound eyes, were observed; both
are here classified as stage VI (Fig. 1).
The Cypris Darva
The cypris of C. dalli (Fig. 1 ) was raised in culture and was
observed to settle.
SUNMARY
B. glandula and P. polymerus were raised in vitro from hatching
to the fourth instar nauplius and C. dalli from hatching to settlement
of the cypris. B. tintinnabulum was raised through stage III. Cultures
were maintained at room temperature and fed on a diet of Platymonas sp.
Larval size, shape, and details of the tail and appendages are presented
for all species and all stages observed. Definite differences between
instars, and between species at the same instar, permit identification
of species and stage of development. Setation formulae, particularly
of the antennule, though of limited value for distinguishing different
22
John B. Snodgrass - 6
species, proved good indicators of specific instars. Body shape and
tail morphology provide the most useful characteristics for species
recognition.
ACKNOWLEDGEMENTS
The writer wishes to express his thanks to Dr. D. P. Abbotof
Hopkins Marine Station, Pacific Grove, California, without whose
editing and kind advice, this paper would not have been presented.
I also wish to thank F. Okamoto, a collegue at Hopkins Marine Station,
who supplied me with later stage C. dalli larvae and helpful hints on
larvae nutrition.
2
John B. Snodgrass -7
MEASUREMENTS OF BARNACLE LARVAE
Chthamalus
dalli
Number of
Total length(u),
Length of
Instar
carapace (u),
specimans
mean am extremes
mean k ext
measured
remes
210
11
—
228 - 243
310
II
17
—
305 - 319
373
III
15
—
315 - 388
333
393
315 - 351
375 - 110
385
510
8
364 - 108
185 - 540
510
1130
VI
110 - 450
520 - 565
510
Cyp.
500 - 515
Width of
body (),
mean &
extremes
115
105 - 119
192
173 - 198
215
210 - 223
294
270 - 302
363
345 - 370
370
365 -372
270
263 - 271


20
John B. Snodgrass - 8
MEASUREMENTS OF BARNACLE LARVAE
Pollicipes polymerus
Length of
Total length(u)
Number of
Instar
carapace(),
mean & extremes
specimans
mean & ext¬
measured
reme
—
247
7
210 - 251
310
8
II
298 - 315
396
16
III
391 - 107
385
123
IV
15
379 - 395
113 - 125
Width of
body (u)
mean &
extremes
115
110 - 118
192
180 - 202
210
237 - 242
291
289 - 301

23/
c
John B. Snodgrass - 7
MEASUREMENTS OF BARNACLE LARVAE
Balanus glandula
Instar
Total Length(u)
Number of
Length of
specimans
mean & extremes
carapace (u).
measured
mean & ext¬
remes
260
14
248 - 272
180
11
163 - 194
—
550
III
17
—
520 - 576
580
190
IV
576 - 583
187 - 196
Width of
body().
mean &
extremes
170
164 -172
210
204 - 211
250
213 - 262
290
280 - 291
Tabi

C
John B..Snodgrass - 10
Balanus tintinnabulum
Total length(u)
Number of
Instar
mean & extremes
specimans
measured
236
11
225 - 210
131
II
12
120 - hh2
510
8
196 - 515
Width of
body (u),
mean &
extremes
115
109 - 116
200
196 - 207
270
259 - 273

233
John B. Snodgrass - 11
CAPTIONS TO FIGURES
Figure 1. Camera lucida drawings of naupliar stages examined; all
are shown in dorsal view at the same scale. A -- stages
1-6 of C. dalli. B -- stages 1-4 of P. polymerus. C --
stages 1-4 of B. glandula. D -- stages 1-3 of B. tintin-
nabulum.
Figure 2.
Camera lucida drawings of the naupliar appendages of C.
dalli. A, - antennule, stages 1-6. A» -- antenna, stages
1-6. M -- mandible, stages 1-4.
Figure 3.
Camera lucida drawing of the naupliar appendages of P.
polymerus. A, -- antennule, stages 1 and 2. A2 -- an-
tenna, stages 1 and 2. M -- mandible, stages 1 and 2.
Camera lucida drawings of the naupliar appendages of B.
Figure 1.
glandula. Aj -- antennule, stages 1-4. A» -- antenna,
stages 1 and 2. M -- mandible, stage 1.
Camera lucida drawings of the tails of stages 2-5 in C.
Figure 5.
dalli, stages 2-4 in P. polymerus and B. glandula, and
stages 2-3 in B. tintinnabulum. C -- Chthamalus dalli,
P -- Pollicipes polymerus, G - Balanus glandula, T --
Balanus tintinnabulum.
Diagrammatic representation of the setae of the appendages
Figure 6.
of the naupliar stages examined in C. dalli. Broken line;
setae without setules. Solid lines; setae with setules.
Lines with lateral branches; stout comb-like setae.
2.
John B. Snodgrass-12
Figure 7.
Diagrammatic representation of the setae of the appendages
of the naupliar stages examined in P. polymerus. Broken
line; setae without setules. Solid lines; setae with setules.
Lines with lateral branches; stout comb-like setae.
Figure 8.
Diagrammatic representation of the setae of the appendages
of the naupliar stages examined in B. glandula.. Broken line;
setae without setules. Solid lines; setae with setules.
Lines with lateral branches; stout comb-like setae.
Figure 9.
Diag
immatic representation of the setae of the appendages
of the naupliar stages examined in B. tintinnabulum.
Broken line; setae without setules. Solid lines; setae
without setules. Lines with lateral branches; stout comb-
like setae.
285
John B. Snodgrass - 13
REFERENCES CITED
Barnes, H. and M. Barnes, 1959. The naupliar stages of Balanus ny
Darwin. Canadian Journal of Zoology, 37: 15-23, figs. 1-4, tabs. 1,2.
Barnes, H. and J. K. Costlow Jr., 1961. The larval stages of Balanus
balanus (L.) da Costa. J. mar. biol. Ass. U.K., hl: 59-68.
Bassindale, R., 1936. The developmental stages of 3 English barnacles,Bala-
nusbalanoides, Chthamalus stellatus, and Verruca stroemia. Proc.
Zool.Soc.Lond., 1: 57-71.
Costlow, J. D. and C. C. Bookhout, 1957. Development of Balanus ebu
in the laboratory. Biol. Bull. 112: 313-323, figs. 1-5, tabs. I, II.
Costlow, J. D. and C. G. Bookhout, 1958. Larval development of Balanus
amphit
trite var. denticulata Broch reared in the laboratory. Biol.
Bull. Woods Hole, 111: 281-295.
Crisp, D. J., 1962. The larval stages of Balanus hameri (Arcanus 1767).
Crustaceana, 1(2): 123 - 130, figs. 1-4, tabs. 1, 2.
Herz, L. E., 1933. The morphology of the later stages of Balanus Crenatus
Biol. Bull., 64: 132 - hhl, plates 1-3, table, I.
Bruguière.
Moyse, J. 1963. A comparison of the value of various flagellates and
diatioms as food for barnacle larvae. Conseil Internat. l'exploration
de la Mer., 28(2): 175-187.
Newman, W. A., 1965. Prospectus on larval cirriped setation formulae.
Crustaceana 9(1): 51-56, figs. 1-2, table 1.
Okamoto, E., 1967. Utilization of Platymonas,
Nitzschia, Dun liella,
Chlorella, and Stichococcus in rearing larvae of the barnacles
Balanus glandula and Chthamalus dalli. Unpublished manuscript.
Sandison, E. E., 1954. The identification of the nauplius of some
South African barnacles with notes on their life histories. Trans.
Roy. Soc. S. Africa, 34: 69 - 101.
236
O5
—
1

1

11
111

1111
11
1111

Exopodite
—



Exopodite
1






111
11

111
11
11
111


1


111
1 1
11
1111
111
Antenna
Mandible
111

111
111
1
1

1111
1111
111
Endopodite

1
111
1

1111
11

1
11
1111
11111

111
Endopodite
111
1
1
11
11
1


1

111





E



F96


9
0


23
Stage
Exopodite

11
11 1
11

Exopodite
- —



Antennule











Antenna


11
1111
Mandible
11
11
11


111
1
111
111
Endopodite




Endopodite

6
O
Otage
Exopodite

Exopodite
Antennule


1
Antenna
Mandible

Endopodite

11
1
1


1
11
Endopodite
1
I


1
111

O
6
O
tage
Exopodite


Exopodite
.
Antennule
1
11
1111

11
11

1
Anfenna
Mandible


S
Endopodite


11 1
Endopodite

111
1

111

1
111
111

24
Suelgan -.18
Fagne I(lttredd)

O




—
sdgn
Siguddde rechen


—2000
I
c
uolaar p: 20.




2
fag I (Rguttachen


CYP
24
W
0











1



Va

Al
2


4 M
A2
2)
M







A2

—


2000
— Pechevu 93
Spodhres-p?
246
Suodgans —p.2
gustgan p.25
Egne 7
Leglssede
2
c2
c3
C4
C5
P2
C2

12
P3
C3

73

P4
G4
100


Susdgran, p. 26
241