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ABSTRACT
The gastreped Calliastema camaliculatum demonstrates a violen
ape espanet the aa Pypedia ellianthidehee
escape mechanism is a highly complex series af reactions that
culmenates in the secretion of a noxious yellow substance from the
animal's hypebranchial gland. The extent to which C. ganaliculatuun
will ge te escape from Eygnepedia without using the secretien
demenstrates a general reluctance to use the methed if it can be
ayoided. The source of this excretion appears to be endogenous to
C. canaliculatum and does not come from its diet. Once secreted, the
snail needs between 4-7 days te regenerate the substance te its tull
capacity, but four days appears to be sufficient for the
effectiveness of the zubstance to reach its full strength.
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INTRODUCTION
The gastroped Calliestema camaliculatum is one of many species
af Mallusca that exhibitz an escape respenze when preveled hy ar
asteroid (Bulleck, 1753; Feder, 1963,1967; Mentgomery, 1767; Mauzey
et al., 1768; Fhillips, 1776; Daytom et al., 1977; Moitza and
Fhillips, 1979; Abbett and Haderlie, 1980; Harrald, 1781, 1982:
Herrlinger, 1783; Watanabe, 1783). C. canaliculatum reacts
particularly vielently to the seastar Fyenspodia heliantheides.
Many of the initial stages of this escape respense are shared with
sther snails of this gemus (Harreld, 1781; Herrlinger, 1783), but
Ca canaliculatum also secretes a moxious yellow substance from its
hypcbranchial gland when stimulated by Eygnepedia (Baxter and Gilly,
personal communication). This added feature to the typical
Calliestoma genus escape mechanism appears to be quite effective.
Herrlinger, 1983, reported that althaugh gastrepeds made up 77 cf
the typical Eymmemedia's diet, enly abeut 1.54 of these were
C. canaliculatum compared to Ca ligatum which makes up almest 25 at
the gastropods eaten. C. ligatum does not display the secretion of
the yellow substance.
The cbjectives of this study were to extensively observe the
stages of C. canaliculatum's escape mechanism from Eyenepodia, to th
extent that it became predictable, and to determine the source af th
noxious exudate as being derived from the snail's diet of the kelp
Macracystis pyrifera, the red algae Gigartina gemymbifema, and the
encrusting invertebrates present on these plants (Hunt, 1977
Sellers, 1977; Abbatt and Haderlie, 1980) ar frem some endogencus
sGurde.
MATERIALS AND METHODS
aperimental imal:
Calligstoma canaliculatum and Eyenspedia heliantheides (here¬
after Eycnapodia) were collected in the kelp beds off of Hopkins
Marine Life Refuge (HMLR) an Foint Cabrille, Pacific Grove,
California using SCUBA. The C. canaliculatum were mest often
faund feeding en the blades of the brown alga Macrecytis
pymifema and occasionally on the red alga Sidartina
gorymbifera on the sandy bettom.
Behavieral Experiments:
A total of thirty C. canaliculatum were used to determine a
characteristic escape response to Fyenepedia. The snails were kept
in running seawater tanks with plenty of kelp to feed on. One snai
at a time was placed in an 8'x 4'x 2' seawater tank where a
Eycnepedia was being held. Individual tube feet were removed from
the seastar using forceps and then applied to varying parts of the
snail so the behavioral response could be observed. A whole Pyenemee
as kalaattlttv
that the respense was the same as that observed when the individual
tube feet were used. The snails were divided into twe groups of
fifteen and placed on either a horizental or vertical substratum
within the tank. After observations were made, the tested snail was
placed in a seperate holding tank than the untested ones. Unce a
characteristic response could be predicted, illustrations were made
(Fiss, 2-9) to demenstrate the escape mechanism.
Secretion Production Exmeriments:
A total of eighty C. camaliculatum (different from the thirty
used in the above experiments) were cellected an Hay 4, 1988 and
induced to release the yellow substance that day. To collect the
exudate, a snail was held with the aperature up while a Fyenepedia
tube foct was applied to the head of the animal. The snail then
retracted inte its shell while secreting the product mixed in
seawater. This mixture was callected using a micrepipet and
stared in a refrigerated flask.
The snails were then randomly divided inte four groups a
twenty and placed inte seperate running seawater tanks, each
cantaining a different fecd source:
TOMK 1 = Kelp with blades encrusted by sessile
invertebrates
TOMH 2 = Kelp with ne invertebrate
TNaia
lancealata
TAMK 4 = Me Focd
All of the kelp, Macrecystis pymifema, and red algae, Gigartina
corymbifera, were collected off of HMLR using SCUBA. Invertebrates
were remaved from the kelp used in TANK 2 by cheasing ycunger
sections of fronds and washing them off and scrubbing them down.
Twenty-four heurs later five snails were removed fram each tari
and numbered 1-5. These were then induced to release their exudate
using the method descriped above. This process was continued to
produce four sampling regimes within ach tank:
GEGUF 1 - snails 4'd i-S were induced to secrete
every day
ROUP  - snailz 'd 4-10 were induced to secrete
every a days
GEQUF 3 - enails 'd li-is were induced to secrete
avery 3 days
GEOUF 4 - snails 4'd 1-2O were induced te secrete
averyday
The test was conducted for twelve days. Each time a snail underwent
the precess of "being slimed" the ameunt of secretion released was
yisibly determined by the ameunt af yellow product that appeared in
the seawater mixture and recorded. The follewing relative scale was
used to quantify the results:
O pane
pana-deak ameunt sereted
waa amaunt secretd
3 weak-maderate ammunt secreted
4  maderate amaunt zecrete
Sm mederate-strang amaunt secreted
strang amount secreted
The "6" an the scale was equivalent to the amount af exudate
sscreted from the average snail just captured from the ccean.
Ofter gellecting the exudate in Mppendorf tubes and labelling
them, a bicassay was run on a live Eygnepedia. The same seastar
was used for all biclegical tests; the Eycnepodia was removed trom
its holding tank and placed in a container (approximately 12"  6'
3 5") with seawater. A control was run using SOul of ardinary
smawater and "shesting" it at the tip of ene arm of the Eyenepediat
ubserve the response. The test consisted of expesing an arm af the
seastar to a MOul sample (e.g., the peoled collection from snails 1-t
fram the Kelp tank on May S was one sample, etc.) of the secretion
and recording the response on a O-o scale of the strength of behavior
response (Fig.1). The Pyenepedia was then rested for 5 minutes
befare the next SOul sample was administerec.
Finally, after the twelve day testing peried the snails ware
returned to the Bay and forty new C. manaliculatum were collected.
These were divided up inte greups af ten and placed in the faur
tankz mentiened abeve. This hatch was nat induced te secrete the
slime befere heing placed inte the tanks. After ane week, all
forty snailz underwent the zegretien precess, and amounts and
bicassay recordings were made as described abeve.
RESULTS:
HehavieralEperimet
A predictable escape respense was determined for .
camaliculatum from Pyenapedia on both horizental and vertical
surfaces. On the herizantal zubstratum the follewing was
abserved:
1) When a Exenepedia tume foct was touched to the head
tentacles af O gamaliculatum, the snail quickly turned
auay from the stimulated area (Fiq. 2).
2) When "attacked" from behind C. canaliculatum lifts up its
shell and begins to ru away. Approximately 50 af the
spails tested in this maner released the hypebranchial
secretien while they were rumming, and this tends te
stick to the snail's shell and mucus trail (Fig. 3).
3) Ofter repeated stimdlatien from behind, the soail begins
te ratate its shell back and forth while threwing its fact
adainst the substratum gausing a samersaulting reactien
away from the Fyenapadia. In 1004 of animals tested, the
yellaw secretion respense takes place in canjustic
with this mevement, wrapping armund the snail as it
retates (Fig. 4).
4) Once on its back the snail continues to rotate its foot
until it is stimulated again by the tube fest. Ot this
peint the animal retracts most of the way into its shell,
dives a final pulse that shects out mare exudate, and
pulls all the way back into itz shell (Fig. S).
Un the vertical substratum the follawing was abserved:
1) When C. canaliculatum was attacked by a tube foot from
helgw its pesition on the substratum (i.e., an the back
af its foot), it ran up, away from the Eyenapedia (Fig. 6).
When the snail was stimulated at its head by the tube
foct, it displayed a substratum release respense (hig. 7)
3) Upon landing upside-down an the horizental surface, E.
canaliculatum tried immedistely to right itself. When
tauched again by the tube feat befare turning ever, the
animal just retracted, pulsed out exudate, and pulled all
the way inte its shell (Figs. S,9). Ne faat-shell rataticr
waz ebserved in these snails.
4) If the animal was given the chance to right itself, it ran
in any direction with its tentacles wildly reaching out
for input. If stimulated with a tube fect the snail
eshibited the same horizontal responses already described.
In addition, all snails, regardless af what surface they were
attached to, responded anly when actually touched by the tube
feet.
Saerationkdutaa
Fig. 10 shows the amount of exudate produced did nat depend on
the foed source aver the twelve day experimental period, but rather
that the major factor in C. canaliculatmim's regeneration of the
eaudate was the time it was given to de so. Alse, as the time
between induced secretion was ingreased so did the strength of the
Eycnepedia reaction to it (Fig. 11).
Of eighty criginal snails that were induced to slime on the
day they were captured, ten of these did not produce the yellow
exudate. The second batch of forty snails that were left in the
identical tanks for ane week before being induced to secrete producee
a 100x positive response, as appesed to the 87.5% of snails in the
griginal batch that secreted the yellow substance. Furthermore, the
forty mnails in batch 2 all secreted at level 4, while the relative
ameunt af slime mecreted by these in match 1 covered the entire mang
fram 0—6.
DISCUSSION
Behavieral Experiments:
One preblem I encountered with these studies was the
reluctance af the Eyenapodia to naturally forage after the C.
ganaliculatum in aquaria. Attempts were made to induce the seastar
inte moving in the general direction of the snail placed in the tank
mut to no avail. Therefore, the technique using individual tube
feet described abeve was used to simulate an attacking seastar.
With a nutural predatery event there would be more variability in
timing and persistence. The described behavier represents a
hierarchy of responses to a sustained attack. It would be of great
interest ta ebserve the behavier in the field te decument its form,
success, and ather consequences.
I noticed that for all thirty snails tested the secretion af
the exudate was a last ditch technique used to escape. The C
canaliculatum were very reluctant to release the product. Also, I
aften faund the snails halding en the substrate with the antericr par
af their feet, while the ventral side of the posterior part of their
feet wrapped up onte the dersal surface of their shells. This has
been observed in Ca ligatum as well (Harrald, 1781), and is
apparently used te maintain a mucus layer on the shell. Therefere,
the observed shell retation reaction must have several functions:
1) It makes it even more difficult for the starfish to get a
seed grip an the snail due te its mucus-layered shell.
It samersaults the snail aut af the pathway af the
starfich (Althauch in Harrald, 181, this behavier in
C.ligatum was not too effective unless the snail was near
alede).
3) Finally, it wraps the yellow exudate around the snail so
that whenever the zeastar attempts to grab hald ot the
prey it is in censtant contact with the noxicus substance.
The substance alse sticks to the mucus trail that the running snail
lays down, therfore the Fyenspedia is faced with the secrection while
still in pursuit of its meal.
The release response I cbserved alse illustrates the extent
to which C. ganaliculatum will ge to avoid using the exudate to
escape. On the vertical zurface the responze differs when centacted
frem abeve or belew. It would be maladaptive to release and fall
inte the multiarmed Eyanepedia, however the snail gains escape
velccity by releasing its hold on the substrate and falling when
attacked from above. This would work on either a vertical reet tace
er on those rare calm eccasions when Pycnepodia climbs kelp to forage
(Baxter, personal communication). Of course, when a snail releases
and falls it may be placing itself in jeopardy from the tentacles of
a waiting anemane, and this is ancther petential predater which may
he defeated by the hypebranchial secretien.
Once C. canaliculatum secreted its hypobranchial slime and
retracted all the way back inte its shell, the animal remained
pulled in for upwards of 30-3 minutes sometimes, even when they
were no langer being proveked by a simulated Fyeneedia.is
seems to be yet more evidence for the observation that the release
of the product is the last stage in this animal's complex escape
response to the seastar; C. canaliculatum cheoses to remain
withdraun and helpless until it seems safe te ceme aut again.
Finally althaugh Myndiads at
studies an its dist have mhoun that this snail is nat a preferred
prey, while its clese relative Ce limatum is a major source or
nutrition for the seastar (Herrlinger, 1783). The latter species
has an almest identical escape respense to that of Ce canaliculattm.
with the impertant exception af the hypchranchial secretion (Harreld,
1781: Herrlinger, 1783). Thus, it seems evident that the intensity
of the Cy canaliculatum escape response is directly correlated to the
Fycnepedia's dietary preferencey this correlation between actively
esgaping from predators and the abundance of prey that ended up in
the diet has been extensively studied using different predater-prey
relationchips (Feder, 1753. 1747; Fhillips, 1974: Dayten at al.,
17771 Maitcza and Fhillips, 1979; Harrald, 1981, 1982; Herrlinger,
1783: Watanabe, 1783).
samationkaedut
Ihe question of whether the moxicus substance is derived form
the diet or by andegenous synthesis seams to be decided in faver ar
andagenous synthesis. The ability to preduce the hypcbranchial
seatidt deethe ftha
(at least aver a twe week peried when secretion was repeatedly
alicited), but rather on the time it has te regenerate the substande
Spails in all four af the experimental tanks were increasingly abl
te secrete the substande as the recavery time between induced
semrationz was increased. Further zupport for this conclusion ceme
fram results ahtained in the secend experiment using ferty new snal
that were left in the tanks for a week before being preveked inte the
mecretion precess. All forty of these snails, after one week with ne
predators to attack them, were able to secrete a large amount
(equivalent te the "4" an the scale) of the hypebranchial substance.
But, the eighty eriginal snails that were induced to secrete the
slime en the day they were collected only had a 87.5 pesitive
megretion rate, and not all of them secreted the "A" equivalent.
This indicates that mame af these snails had prebably been recently
attacked in the field and ferced to use the exudate to escape and not
had time te regenerate it befare they were captured. This has the
matential to allow predater-prey studies in free ranging pepulations
by messuring the numbers af attacks that were not successtal.
Furthermere, when comparing the averages calculated for both
the amounts and the bicassay reactions (Figs. 10,11), it appeare
that four days is not encugh time to generate the strang "
reading for the ameunt of secreticn released, but it is a lang
enough time to generate a strengly velatile secretion, therstere
1) The recevery peried necessary te preduce the largest
amaunt of the exudate lies somewhere between the lengest
tested pericd, 4 days, and the ebserved peried at whicn
100 af the Ce canaliculatum population secreted the
sauvalattte aday
2) Singe the "4" on the Eyenepedia reaction scale did net
gerrempond to the "A" an the scale for ameunt at yellew
chzeryed, it appears that the active reagent af the
gampaund daas nat lie in the yellaw part af the substance.
This latter observation is supperted by bicchemical tests run on
10
C
the secretion (Smaby, personal communicatien).
SUMMARY
The purpose of this study was to figure out the dynamics af the
escape response that C. canaliculatum exhibits in the presence of th
predater Eycnopedia, in terms of both the behavioral and production
mechanisms. It appears that the diet af the snail has no impact an
its ability to generate a volatile secretion. C. gamaliculatum can
regenerate the substance in large and effective quantities, but this
requires over four days to achieve maximum amount and titer. Ameunt
of secretion in the experiment were measured by eye in terms at the
yellowness of the mixture. It would be more accurate to develep a
spectrophetometris method. It appears that the active ingredient
dees not necessarily lie in the yellow factor because the strongest
reactions in the bicassay were ebserved even theuch the ancurt
secreted did not reach the peak on the scale. If the active compeun
(er compounds) can be identified a quantitative measure can be
developed. The snail also goes through a rigorous patterns of
predictable actions before it will exude the substance, suggesting
quite a bit of reluctance in using this mechanism unless absolutely
necessary.
ACKNOMLEDGEMENTS
Chuck Baxter deserves mere thanks than can possibly be
expressed in a few words; he was infinately available wheneyer I
needed him to help me solve my many problems, and the suggestions he
dave me are a large part of the reason this preject was completed.
I would alse like to express my unending gratitude to Tom Otis.
Niels Smaby, and Tiffany Tom for going above and beyond the call of
Guty when it came to diving for me whenever it was necessary (which
turned cut to be quite often). Thanks to Dre. William Gilly and
Stuart Thompsen for their suggestions and interest in the "slime".
and to Rob Sweezey and Chris Fatton for taking time eut to help on
the graphics at a period when their time was in the greatest demand,
Finally, a big thank you to the rest of the class, especially Niels
(my partnær in "slime") and the rest of the residents of 1009 Ferest
Evende, for making these past twe monthe a couple of the mest
memerable in my life.
LITERATURE CITED
Abbett, D.F. and E.C. Haderlie. 1980. Froscbrarichias Marine smails
Ins Intertidal invertebrates of Califormia. Morris, R.H., D.
Ahbett and E.C. Haderlie teds). Stanford University Press,
Stanford, Calif. p. 230-307.
Fulleck, T.H. 1953. Fredater reccgniticn and escape responses ot
some intertidal gastropods in the presence of starfish.
Behavior S: 130-140.
Dayton, D.K., R.J Rosenthal, L.C. Mayer and T. Antezena. 1977
Egpulatien structures and foraging hiclogy af the predacecus
Chilean asteroid Meyemaster gelantingsus and the escape bielot
of its prey. Mar. Eiel. 39: 361-370.
Feder, H.M. 1943. Gastrepod defense respenses and their
effectiveness in reducing predation by starfishes. Ecclcgy 44
—12
Feder, H.M. 1967. Organisms response to predatory seastars. Sarsi
29: 371-393.
Harrold, C. 1981. Feeding ecology of the asteroid Eisaster
didanteus in a kelp forest system: Prey selection, predator-
pray interactions, and energenics. Fh.D. Diss., Univ. Gr
Calif., Santa Cruz. 54-59 p.
Harrold. C. 198. Escape resonse and prey availability in kelp
forest predater-prey system. Am. Nat. 119: 132-135.
Herrlinger, T.J. 1983. The diet and predator-prey relationships e
the seastar Eygnopodia haliantheidms from a central California
kelp forest. M.A. Thesis, San Jose State University. 25-2 p
Population dynamics of Tegula and Calligstema in
Hunt, D.E. 1977.
Carmel Bay, with special reference to kelp harvesting. M.G.
Thesis, Sam Francisce State University, S1 p.
Mauzey, K.F., C. Eirkeland and F.K. Dayton. 1968. Feeding behavic
of the astercids and escape respenses of their prey in the Fuge
Sound regien. Ecelagy 49: 603-619.
Moitza, D.J. and D.W. Fhillips. 1979. Frey defense, predater
preference, and nen-randem diet: The interactions between
Eycnepedia heliantheides and two species of sea urchins. Har.
Bial. SS: 299-304.
Montgomery, D.H. 1947. Responses of two Haliotid gastropods,
Hallictis assimilis and Halligtis rufesgens to the forcipulate
astnikaealta
Valigar
Fhillips, D.W. 1974. The effect of a species-specific avoidance
response to predatory starfish en the intertidal distribution
two gastropeds. Oecologia 23: 83-94.
Sellers, R.G., Jr. 1977. The diets of four species of Callicstema
and some aspects af their distribution within a kelp bed. M.
Thesis, Stanferd University, Hepkins Marine Station.
atana a deoth
dastropods: Contrasting adaptations of closely-related prey
species. J. Exp. Mar. Biel. Ecel. 71: 257-270.
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FIGURE LEGEND
Figure 1. Quantification of the Eymmepedia's reactions in the
bidassay. O m na exn, same as cantral with seawater 1
arm af zeastar wraps aver tube feet; 2 retraction et
arm, fallawed by streching aut af tube feet 3slight
arm curl; 4 = curl seen in "3", follewed by lifting and
halding arm vertically: S - strang curl af arm; a ever
tighter curl, followed by starfish meving away from area.
Ce ganaliculatum cames in contact with a Eyenemedia tube
Figure
fast at its anterier and and hegins to turn away.
Cw camaliculatum is proveked by Fyenmpedia tube fect from
Figure 3.
the anterier and, resulting in the snail lifting up it
shell and running away, sometimes secreting the yelle
hypsbrancial subztange at the same t.
After repeated pesterier provecation with a Fymnapadia
Figure 4.
tube foot. Cy canaliculatum begins to spin its shell back
and farth and thrawz itzelf forward in a zamersaulting
metion while secreting the hymchranchial substande.
Frevecation centinuz after C gamaliculatum turns itself
Fig
ayer, and the snail retracts mest of the way inteits
shell, pulses aut mere af the yellow substance, and pulls
all way back inte ithel 1.
Cy ganaliculatum is attacked on a vertical surface from
Figura 6.
the pesterior and hy a Fyanapadia tube fect causing the
mnail to run up the substratum.
Ea gamaliculatum displaym the substratum release respense
Figure 7.
after Being pravaked Trem the anteriar end an a ver tical
surface by a Myanmpadia tube foct.
Fallauin sustatu alase.  aaliculatum land
Figure.
itz back and tries ta rightitslt.
Cy canaliculatum is proveked by a tube foot before being
Figure
able to right itself and it quickly pulses aut the yella
substanze and retracts inte itz sheil.
mach paint an the graph is an average af the ameunt cr
Figure 10.
vellow substance secreted by each group af snails within
the four seperate tanks thraughaut the testing per iad.
The visually determined ameunts based an the yelicwmes
af the mixture were quantified using the scale deserid
in the Materials and Mathads zectien of this paper.
Wach peint an the graph is an average af the reactier
Figure 11.
displayed by Exenmpadia to the yellow substande secreted
hy sach greup af snails within the four seperate tan
throughout the testing peried. The visually qualitied
O
responses wera quantified using the zcale deseried
the Materialz and Metheds mection af this paper.
HGURE L. QUANTIF ICATION oF
PYCNOPODIA BIOASSAV
NONE. (- NO RXN
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