effects of feeding on thermal selection...
TRANSCRIPT
Effects of feeding on thermalselection by Constrictor constrictor
Item Type text; Thesis-Reproduction (electronic)
Authors Combest, Wendell Lee, 1951-
Publisher The University of Arizona.
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Link to Item http://hdl.handle.net/10150/347972
EFFECTS OF FEEDING ON THERMAL SELECTION
BY CONSTRICTOR CONSTRICTOR
by
W endell Lee C om best
A T hesis Subm itted to the F acu lty of the
DEPARTMENT OF CELL AND DEVELOPMENTAL BIOLOGY
In P a rtia l F u lfillm en t of th e R equirem ents For th e D egree of
MASTER OF SCIENCE WITH A MAJOR IN ZOOLOGY
In the G raduate C o llege
THE UNIVERSITY OF ARIZONA
1 9 7 6
STATEMENT BY AUTHOR
This th e s is h as been subm itted in p a rtia l fu lfillm en t of r e q u irem en ts for an ad vanced d eg ree a t The U n iv e rsity of Arizona and is d ep o s ite d in the U n iv e rs ity L ibrary to be made a v a ila b le to borrow ers under ru le s of th e L ibrary .
Brief q u o ta tio n s from th is th e s is are a llo w ab le w ithout s p e c ia l p e rm iss io n , provided th a t acc u ra te acknow ledgm ent of sou rce is m ade. R eq u ests for perm ission for ex tended q u o ta tio n from or rep roduction of th is m anuscrip t in w hole or in part m ay be gran ted by th e head of the m ajor departm ent or th e D ean of th e G raduate C o llege w hen in h is ju d g m ent th e proposed u se of the m ateria l is in th e in te re s ts of s c h o la rsh ip . In a l l o ther in s ta n c e s , h o w ev er, perm ission m ust be ob ta ined from th e au th o r.
SIGNED: .
APPROVAL BY THESIS DIRECTOR
This th e s is .h a s been approved on th e d a te shown below :
ROBERT B. CHIASSONP rofesso r of Zoology
TABLE OF CONTENTS
LIST OF ILLUSTRATIONS
LIST OF TABLES . . . .
ABSTRACT . . . . . . .
INTRODUCTION . . . .
MATERIALS AND METHODS . . .
RESULTS ........................ . . . . . .
DISCUSSION AND CONCLUSIONS
REFERENCES............................... . .
LIST OF ILLUSTRATIONS
Figure Page
-I* F loorp lan of g rad ien t cham ber w ith 12 u n its u sed/ a s p o s itio n m arkers (51cm x 51cm x 1 9 8 c m ) . . 5
2* S u b stra te tem p era tu res a t each p o s itio n in th e g rad ien t . . . 5
3 . S e lec ted stom ach tem p era tu res for boa #1 fed a t 1200 . . . '. 11
4 . S e lec ted stom ach p o s itio n s for boa #1 fed a t 1200 ................ ... - 11
5« S e le c te d stom ach tem p era tu res for boa #2 fed a t 1200 . . . . 12
6« S e lec ted stom ach p o s itio n s for boa #2 fed a t 1200 . . . . . . 12
7 . S e le c te d stom ach tem pera tu res for boa #3 fed a t 1200 . . . . 13
8 . S e le c te d stom ach p o s itio n s for boa #3 fed a t 1200 .......... 13
9 . . S elected , stom ach tem pera tu res for boa #1 fed a t 1700 . . . . 14
10* .S e lec te d stom ach p o s itio n s for boa #1 fed a t 1700 ..................... 14
11. ; S e lec ted stom ach tem pera tu res for boa #2 fed a t 1700 . . . . 15
12. S e le c te d stom ach p o s itio n s for boa #2 fed a t 1700 . . . . . . 1 5 '
13. S e lec ted stom ach tem p era tu res for boa #3 fed a t 1700 . . . .- 16
14 . S e le c ted stom ach p o s itio n s for boa #3 fed a t 1700 . . . . . . 16
15 . S e le c ted stom ach tem pera tu res for boa #1 fed a t 2200 . . . . 17
16 . S e lec ted stom ach p o s itio n s for boa #1 fed a t 2200 .................... 17
17 . . S e lec ted stom ach tem p era tu res for boa #2 fed a t 2200 . . . . 18
18 . S e lec ted stom ach p o s itio n s for boa #2 fed a t 2200 .................. 18
iv
V
LIST OF ILLUSTRATIONS—C ontinued
Figure Page
19. ; S e lec ted s tom ach tem p era tu res for boa #3 fed a t 2200 . . . . . . 19
20 . S e lec ted stom ach p o s itio n s for boa #3 fed a t 2200 . . . . . . . 19
LIST OF TABLES
Table Page
1 . M ean S e lec ted Stom ach Tem perature °C „ 9
2 . Voluntary Maximum T em peratures °C . . . . . . . . . . 9
ABSTRACT
The e ffe c ts of feed in g upon g a s tr ic tem peratu re s e le c tio n of
sp ec im en s of C o n s tric to r c o n s tr ic to r w as in v e s tig a te d in a labo ra to ry
therm al g ra d ie n t. Fed sn ak es dem onstra ted a s ig n if ic a n tly h igher therm al- . -' i .
p reference than did nonfed a n im a ls . The sn ak es m ain ta ined a more or
l e s s reg u la r cy c le of tem peratu re s e le c tio n approxim ating 24 h o u rs .
E levated stom ach tem p era tu res u su a lly occurred in the la te even ing and
con tinued un til n ea rly m idnigh t, w ith th e lo w es t tem p era tu res recorded
in th e ea rly to la te m orning h o u rs . F eed ing did not a p p re c ia b ly a ffec t
th is b a s ic c y c le . All tem perature f lu c tu a tio n s were c o rre la ted w ith
stom ach lo ca tio n reco rd s and w ere due to the snake a c tiv e ly changing
h is p o sitio n in th e g rad ien t.
The vo lun tary therm al maximum w as found to be g rea te r in fed
sn ak es when com pared to nonfed s n a k e s . Time of fe e d in g , w hether
1200, 1700, or 2200, had l i t t le to no e f fe c t on e ith e r th e tem peratu re
se le c te d or the 24-hour c y c le s . ,
INTRODUCTION
Ambient tem peratu re has been shown to have an im portan t
in flu en c e on the ra te of g a s tr ic d ig e s tio n in many a n im a ls . Tempera
tu re e f fe c ts on feed ing and d ig e s tio n in f ish are w e ll kn o w n . Brett
an d H iggs (1970) dem onstra ted th a t the tim e for com plete d ig e s tio n
d e c re a se d for 147 hours a t 3 °C to 18 hours a t 23 °C in fingerling
so ck ey e sa lm o n . The ra te of d ig e s tio n in c re a se d w ith in c rea s in g tem
p era tu re from 20 °C to 23 °C in O ph iocephalus p u n c ta tu s (G erald 1973).
The p e rcen tag e of food rem aining in the stom ach of the ch an n e l c a tf ish
in c re a se d w ith d e c re a s in g w a te r tem pera tu re from 29 °C to 10 °C
(S h rab le , T iem eier, and D eyve 1969). A sadi (1967) rep o rted th a t the
s e c re tio n of d ig e s tiv e enzym es by ch an n e l c a tf ish w as low a t w a te r
tem p era tu res below 1 5 .5 ° C . Large mouth b a s s M icrop terus sa lm o ides
m ain ta in ed a t tem p era tu res of 10 , 1 5 , 2 0 , and 25 ° c req u ired 50 , 37 ,
2 4 , and 19 hours re sp e c tiv e ly fo r to ta l g a s tr ic d ig e s tio n (M olnar and
Tolg 1962).
E vidence for s im ila r tem peratu re e f fe c ts on feed in g and d i
g e s tio n a re p re se n t in mammals (M aitrya 1961) and am ph ib ians (Teorell
1949 , Sm it 1964, B ustard 1967). K epenis and M cM anus (1974) found
th a t the tu rtle C hrysem ys p ic ta w as le th a rg ic and did no t a c c e p t food a t
15 0C . W ith an in c re a se in am bien t tem p e ra tu re , bo th food in tak e and
fe c a l and u rine p roduction in c re a s e d . After fe e d in g , sp ec im en s of
P seudem ys sc rip ta in c re a se d th e ir therm al preferendum an d .b ask in g b eh av
io r (M oll and Legler 1971). C hem ical d ig e s tio n did no t o ccu r for two
w eek s in tu r tle s exp o sed to low tem p era tu res (Fox and M u sacch ia 1959).
M ost of th e work on p h y s io lo g ica l e ffe c ts of tem pera tu re on
sn ak es d e a ls w ith Og consum ption and h ea rt r a te . An in c re a se in body
tem p era tu re up to a ce rta in maximum is fo llow ed by an in c re a se in both
O2 consum ption and h ea rt ra te in se v e ra l s p e c ie s (Jacobsen and
W hitford 1971 , G reenw ald 1971, Buikema and Armitage 1969 , D m 'el and
Borut 1972).
- S k oczy las (1970a) found th a t d ig e s tio n in th e stom ach of the
g ra s s s n a k e , M atrix n a trix L . , ta k e s p la ce m ost rap id ly a t a tem pera
tu re of 25 °C and may be only s lig h tly s low er a t 35 ° C . At 15 °C
d ig e s tio n in th e g ra s s snake is very slow or com plete ly in h ib ited and
n ev er o ccu rs a t 5 °C (Skoczylas 1 9 7 0 a). In the k ing s n a k e , Lam propeltis
q e tu lu s ,g a s tr ic d ig e s tio n requ ired 10 to 40 hours a t a tem peratu re of
32 ° C , about 48 hours a t 22 ° C , and d ig e s tio n did not o ccu r a t 7 °C
(Root 1961).
In c re a se d tem peratu re is known to in c re a se th re e g a s tr ic a c t iv
i t ie s : (1) a c tiv ity of d ig e s tiv e e n z y m e s , (2) g a s tr ic ju ic e s e c re t io n ,
and (3) g a s tr ic m otility (Smit 1967). The q u a n ti ty , pH , and p ro teo ly tic
a c tiv ity of g a s tr ic ju ic e a re a lso a ffe c te d by tem peratu re (Skoczylas
1970b).; T hus, to an optimum le v e l , in c re a s in g the tem pera tu re
f a c i l i ta te s the d ig e s tiv e p ro c e s s . Above th e optimum le v e l , the tem
p era tu re ap p ea rs to have a re ta rd in g e ffec t in the g ra s s snake
(S koczylas 1970b) and d ig e s tio n occurred a t a s low er ra te a t 35 °C
th an a t 25 ° C .
C ow les and Bogert (1944) repo rted d ig e s tiv e fu n c tio n s in the
liz a rd Sceloporus m ag is te r may be fa c i l i ta te d by therm oregulatory
b eh av io r. E leva ted body tem p era tu res w ere recorded in a boa c o n s tr ic to r
one day a f te r feed ing by M cG innis and M oore (1969) and by K itchell
(1969). They o b serv ed th a t m ean body tem p era tu res a f te r feed ing w ere
h igher th an in unfed c o n tro ls . Regal (1966) a lso o b se rv ed th a t many
re p tile s norm ally a c tiv e a t low tem p era tu res seek h ig h er tem p era tu res
a fte r feed ing and concluded th a t the p re se n c e or a b se n c e of food in the
stom ach may be a d e term inan t in therm oregulatory b eh av io r .
A side from the o b se rv a tio n s of M cG innis and M oore (1969)
and Regal (1966), th e e ffe c t of feed ing on therm al s e le c tio n in
C o n s tric to r c o n s tr ic to r h as no t b een s tu d ie d . The p re se n t in v e s tig a
tio n w as undertaken to provide q u an tita tiv e da ta on fed and nonfed
s n a k e s .
MATERIALS AND METHODS
C o n stric to r co n s tr ic to r from northern S in a lo a , M exico w ere
c o lle c te d in Septem ber 1973, and h e ld in 51cm x 91cm x 122cm c a g e s
u n til M ay 1 9 7 5 / The to p and one s id e of, each cag e w as co n s tru c ted of
c le a r p le x ig la s . The floor and o ther th ree s id e s w ere of p lyw ood . Each
cag e housed th re e s n a k e s . A th e rm o s ta tic a lly -c o n tro lle d e le c tr ic h e a te r
m ain ta ined tem p era tu res in th e ca g es a t 29 °C during th e lig h t period ,
and a t 26 °C during th e dark period . Light w as provided from 0600 to
2000 by overhead f lu o re sce n t l ig h ts . . W ater w as a v a ila b le ad libitum
and food w as provided a t frequen t in te rv a ls .
Therm oregulatory behav io r w as observed w hile th e snake w as
en c lo sed in a therm al g rad ien t cham ber (F ig s . 1 and 2 ). The g rad ien t
cham ber w as co n s tru c ted w ith a g a lv an ized m etal bottom and an arch ing
p lex ig las top forming the lo n g itu d in a l h a lf of a cy lin d er w ith th e d im en
sio n s 51cm x 51cm x 198cm . The ends of th e h a lf cy lin d er w ere f itted
w ith w ooden doors through w hich the sn ak es w ere in tro d u ced to the
ch am b er. The m etal bottom w as covered by 1cm of sand and e lev a ted
above a ta b le s u rfa c e . Two 100-w att lig h t bu lbs under one end of the
cham ber provided a tem peratu re of 55 °C in th e cham ber d ire c tly above
th e b u lb s . The o p p o site end of th e cham ber w as coo led by re frig e ra te d
w ater c ircu la ted in a co iled copper tu b e . The tem peratu re on th e su rface
5
©1 w ater□
a
F ig . 1. F loorp lan of g rad ien t cham ber w ith 12 u n its u sed a s p o sitio n m arkers (51cm x 51cm x 198cm ).
O 60--
3 0 -
w io
F ig . 2 . S u b stra te tem p era tu res a t e a c h p o s itio n in th e g ra d ie n t.
. : ' . ' ' ' ■. of the- w a te r c o ils w as 18 °C w hile the a rea be tw een th e c o ils w as
m ain ta ined a t 20 ° C . S u b stra te tem p era tu res w ere determ ined w ith a
m ercury therm om eter in tro d u ced through sm all h o les in th e s id e s of th e
cham ber.
The s h a k e 's s tom ach tem peratu re w as determ ined by the u se o f
a b a tte ry -o p e ra te d te m p e ra tu re -se n s itiv e tra n sm itte r and an AM rad io
re c e iv e r . P u lse s from th e tra n sm itte r w ere re ce iv e d by th e rad io r e
c e iv e r , reco rded on a ta p e rec o rd e r , and tim ed w ith a 1 /1 0 second stop
w a tc h . The tra n sm itte r w as co n s tru c ted fo llow ing th e d e sc rip tio n of
MacKay (1970) and ca lib ra te d over a range of 20 °C to 42 °C w ith an
Ertco-76m m im m ersion m ercury therm om eter having a range of -5 °C to
105 ° C .
The tra n sm itte r w as e n c a se d in s ilic o n e and a tta c h e d to a
s trin g before feed ing to the s n a k e . The s ilic o n e e n c a se d tra n sm itte r
w as fo rc e -fe d to the nonfed a n im a l, but w as in se r te d in a fre sh ly
k ille d labo ra to ry ra t w hich w as then fed to the ex p erim en ta l snake to
o b ta in tem p era tu res a fte r e a tin g . The tra n sm itte r w as re tr ie v e d a t th e
co n c lu s io n of each experim ent by w ithd raw al of the a tta c h e d s tr in g .
Stom ach tem pera tu re m easurem ents w ere reco rd ed a t 3 - hour
in te rv a ls beg inn ing a t the tim e the tra n sm itte r w as in tro d u ced in to th e
sn a k e . Fed (tran sm itte r in a ra t c a rc a s s ) and nonfed con tro l tem pera
tu re m easu rem en ts w ere in it ia te d a t 1 2 00 , 1700, and 2200 , and
co n tin u ed over a 9 6 -h o u r p e rio d . A l e a s t sq u ares p e rio d ic re g re ss io n
lin e w as draw n through the d a ta p o in ts . A nalysis of v a rian ce u s in g an
f t e s t w ith a random ized b lock d es ig n w as u se d to determ ine le v e ls of- . x .
s ig n if ic a n c e .
RESULTS
Stom ach tem p era tu res s e le c te d over a 96-hour t e s t period are
p re sen ted in F igures 3 through 20. Therm al s e le c tio n in C o n s tric to r
c o n s tr ic to r ap p ears to be of a cy c lic n a tu re w ith c y c le s approxim ating
24 h o u rs „ The h ig h e s t tem p era tu res w ere s e le c te d in th e .la te ev en in g ;
b e tw een a few hours prior to s u n se t and approx im ate ly m id n ig h t. The
lo w e s t tem p era tu res w ere se le c te d be tw een the ea rly m orning hours and
n o o n . R ecordings of stom ach p o s itio n and tem peratu re re la te the tem
perature f lu c tu a tio n s to the behav io r of the sn ak es who a c tiv e ly change
th e ir p o s itio n in th e therm al g rad ien t (F ig s . 3 -2 0 , p ag es 1 1 -1 9 ).
The f ir s t m ajor a c tiv ity period ap peared a fte r a low tem peratu re
w as rea ch e d in th e e a rly to la te morning w hen the sn ak e moved tow ard
th e warm end of th e g ra d ien t. The seco n d m ajor a c tiv ity period u su a lly
occurred betw een m idnight and dawn when th e snak e moved tow ard the
co o ler end of th e g rad ie n t. T hese o b se rv a tio n s ag ree w ith M cG innis and
M bore (1969), who found the a c tiv ity of C o n stric to r c o n s tr ic to r during
a 24-hour period to be bim odal w ith m ajor m ovem ents occu rring about
noon and about m idnigh t.i '
M ean s e le c te d stom ach tem p era tu res are p re sen ted in Table 1.
F eeding re su lte d in a s ig n if ic a n t in c re a se in m ean s e le c te d tem p era tu re ,
bu t did not a lte r th e b a s ic d iurnal cy c le observed in nonfed s n a k e s . Fed
8
9
Table 1. M ean S e lec ted Stom ach T em peratures ° C .
F eed ing Snake 1200Time of F eed ing
1700 2200
#1 2 9 .1 2 9 .2 . 3 1 .1
Fed ■ . #2. 2 6 .8 3 1 .3 3 0 .7
#3 3 1 .7 2 9 .9 3 0 .8
. #1 2 8 .2 2 5 .7 - 2 7 .0
Nonfed #2 2 5 .5 2 6 .1 2 5 .6
#3 2 7 .4 2 7 .2 2 8 .5
Table 2. V oluntary M aximum T em peratures ° P .
Feeding Snake 120.0Time of F eed ing
1700 2200
#1 3 6 .6 3 6 .9 3 6 .1
Fed . #2 3 5 .0 3 6 .4 3 5 .2
#3 3 6 .2 3 6 .0 3 5 .1
#1 3 5 .2 3 6 .1 3 2 .0
NOnfed #2 3 0 .0 3 3 .8 3 3 .8
' #3 3 3 .9 3 1 .2 3 1 .2
■ ::: . ■ : 10
sn ak es b eh av lo ra lly m ain ta ined more e le v a te d te m p e ra tu re s . D iffe rences
in m ean tem perature s e le c t io n due to th e time of feed in g w ere not s ig n if
ic a n t . . ;
Voluntary therm al maximum a s defined by C ow les an d Bogert
(1944) w as h igher in fed sn a k e s than in nonfed an im als (Table 2). The
h ig h e s t s tom ach tem perature recorded w as 3 6 .9 °G in a fed sn a k e . The
mean vo lun tary therm al maximum for the th ree fed s n a k e s w as 3 6 .5 ° C ,
and for the th ree nonfed sn ak es w as 3 4 .6 °C . Brattstrom (1965) reported
a vo lun tary therm al maximum of 34 ° C Z and M cG inn is and M oore (1969)
recorded a maximum of 3 8 .5 0C for a spec im en of C o n s tr ic to r c o n s t r ic to r .
The la t te r au thors observed the 3 8 .5 °C read ing only o n c e , and i t w as
th e ir only record ing above 30 ° C .
Voluntary minimum tem pera tu res of 2 1 .3 °C and 2 0 .1 °C w ere
recorded for a fed and a nonfed sn a k e , r e s p e c t iv e ly . There were no
s ig n if ican t d iffe ren ces be tw een fed and nonfed sn ak es in th is r e s p e c t .
Figures 3> 5 , 7 , 9 , 11, 13, 15, 17 , 19: (Selected Stomach Temperatures) .
.F igures 4 , 6 , 8 , 10 , 12 , 14 , 16 , 18 , 20: (Selected Stomach P o s i t io n s ) ,.
© — Observed, pos ition points for fed snake
O bserved pos ition poin ts for nonfed ^ *"* snake.i- • '
. (See F i g . 1 and Fig. 2 for su b s t ra te tempera tures a t e ach p o s i t io n . )
L east sq u a res periodic re g re s s io n line for fed snake
L east squares period ic re g re s s io n line for nonfed snake
M ean tem pera tu res for fed snake
M ean tem pera tu res for nonfed snake
^/ / — Dark period (2000 - 0600)
O bserved da ta points for fed snake
O - O bserved da ta poin ts for nonfed . snake
11
36+
-2 9 .1-2 8 .2
• s
CZD,2 4 --
22 - -
Hours after FeedingFig . 3. S e lec ted s tom ach tem pera tu res for boa #1 fed a t 1200.
12- -
# i
S 8 -
# # #
E 6 - -
o o 00
O O< O
Hours after Feeding
Fig. 4. S e lec ted stom ach pos it io n s for boa #1 fed a t 1200.
1 2
3 64
34--
32--
5 3 0 - ,
E 28--
26--V -
/*C/D
24--
22 -
u L
Hours after FeedingFig. 5. S e lec ted stom ach tem pera tu res for boa #2 fed a t 1200.
1 2 -
10- - #
i »# i
Hours a fter FeedingFig. 6. Se lec ted s tomach pos i t ions for boa #2 fed a t 1200.
13
36-
A
•31.7
E 2 8 -f •27.4
2 6 -
C/D24--
2 2 -
Hours after FeedingF ig . 7. S e lec ted stom ach tem pera tu res for boa #3 fed a t 1200.
12-
6 6g in-- s • • • « # • O• e OO o
#
OO
o 4_.
o o o'<> o o
Hours after Feeding
Fig. 8. Se lec ted stomach pos i t ions for boa #3 fed a t 1200.
14
36 + oo
34--
32--
B 30i-•29.2
to 26- i '----- 25.7/ “
uD2 4 -
22-
Hours after FeedingFig . 9. S e lec ted s tom ach tem pera tu res for boa #1 fed a t 1700
oo10-
• • •• o
##
O DO o o or o o go o
o o o
Hours a f te r FeedingFig. 10. S e lec ted s tomach pos i t ions for boa #1 fed a t 1700.
15
36--
o #
-3U
E 28--
26.1
CO
22- -
Hours after Feeding Fig . 11. S e lec ted s tom ach tem pera tu res for boa #2 fed a t 1700.
8-
0 o§ 6~ *
©oo o
Hours af te r FeedingFig. 12. Se lec ted s tomach pos i t ions for boa #2 fed a t 1700.
364-
34--
•31.2
— y------------\ --------- 07— v — /---- 27.2— r 10fD1■M
26--
co2 4 --
22 -
Hours after FeedingFig. 13. S e lec ted s tom ach tem pera tu res for boa #3 fed a t 1700.
12- -
4->
§-o 10--,.##fe, "5 8 - - « > 0•6 ° fOo 6”+-»(0
» • •«• #
C O O
• #
:o■Mto
£ O O
Hours after FeedingFig. 14. Se lec ted s tomach pos i t ions for boa #3 fed a t 1700.
36+
# #
32--
CO 062 4 --
2 2 -
ezzHours after Feeding
Fig. 15. S e lec ted stom ach tem pera tu res for boa #1 fed a t 2200.
1 2 -
o<#e
• • s> 0
o oE 6 - -
oo06 0
Hours after Feeding
Fig. 16. S e lec ted stom ach po s it io n s for boa #1 fed a t 2200.
18
30.730--
t - i
--A - "t 25.6CO
2 2 -
N , , W , , W , , W" F70 6 12 18 24 30 36 42 48 54 60 66 72 78 84 90 96
Hours a fter Feeding Figure 17. S e lec ted stom ach tem pera tu res for boa #2 fed a t 2200.
1 2 - • •cQ)
&
10 - - • I • •• ee
• ex:oro§+j
• IWO§a
Hours after FeedingFig. 18. Se lec ted stomach p os i t ions for boa #2 fed at 2200.
19
32--•30.8
— 28.5E 2 8 --
2 6 --
co 24--
22- -
m , ,n72 78 84 90 960 6 12 18 24 30 36 42 48 54 60 66 : :
Hours a fter FeedingFig. 19. S e lec ted stom ach tem pera tu res for boa #3 fed a t 2200.
12- -
I mi£Cn o c 8 - -
o • • • # • • O# ## *
# #
o o o0fD1■M o o o03
4-1o§03
£
Hours a f te r Feed ingFig. 20. Se lec ted s tomach pos i t ions for boa #3 a t 2200.
DISCUSSION AND CONCLUSIONS
The in c re a se in both maximum volun tary and mean preferred
tem perature in fed sn ak es w as c o n s is te n t w ith Regal.'s (1966) o b se rv a
tio n th a t C o n s tr ic to r co n s tr ic to r w as more therm ophilic a f te r feeding
than befo re . This therm ophilia is s im ila r to th a t found in tu r t le s
(Gatten 1974, Moll and Legle r 1971). H ow ever, r e s u l t s from Caiman
c rocod ilus in d ica te th a t preferred tem pera tu res are in d ep en d en t of time
s in ce l a s t feed ing (Diefenbach 1975). The h igher s tom ach tem pera tu res
s e le c te d compared w ith Sm it 's (1967) finding th a t d ig e s t iv e p ro c e s s e s
are more e ff ic ien t a t a tem perature s lig h tly h igher th an the normal m ean
body tem perature in f i s h . H ydrochloric a c id co n cen tra tio n in the g a s t r ic
ju ice and p ro teo ly tic a c t iv i ty in the s tom ach proceed f a s te r a t e le v a te d
body tem pera tu res (D iefenbach 1975, S koczy las 1 9 7 0 a , and Asadi 1967).
E levated stom ach tem pera tu res cou ld be a c t in g to in c re a se
blood flow to the g a s tr ic g lands d e liver ing more oxygen and nu trien ts to
c e l l s producing the g a s tr ic se c re t io n s a s in frogs (Smit 1964). Lucey
(1974) found th a t heating of the sk in or c a rap ace of the tu r t le s P .
f loridana and C . se rpen tina w as fo llow ed by an in c re a se in blood flow
to the h ea ted a r e a . An in c re a se in blood flow to the s tom ach brought
abou t an in c re a se in a c id sec re t io n in d o g s '(P e te r e t a l . 1962). An
in terrup tion of the blood supply to the stom ach of the in ta c t dog rap id ly
‘ ■ ' . ■ ■ ■ ■ 2 0 ■ v : : v -
in d u ces a c e s s a t io n of sec re t io n (Coy e t ' a l . 1951). The in c re a se d
tem pera tu res would a lso exert a d irec t e ffec t a c c e le ra t in g the m etabo
lism of the g a s tr ic g land c e l l s and thereby in c re a s in g th e ir production
of a c id and p ro teo ly tic enzym es (Teorell 1949). In c re a s e s in s tom ach
m otility due to in c r e a s e s in tem perature would a lso a c c e le r a te g a s tr ic
s e c re t io n s (Smit 1967). At low am bient te m p e ra tu re s , s tom ach HC1
se c re t io n and p ro teo ly tic a c t iv i ty are a t a minimum or to ta l ly la c k in g ,
thus inh ib iting g a s tr ic d ig es t io n (Skoczylas 1970a, A sadi 1967).
Optimum d ig e s t iv e a c t iv i ty in C o n s tr ic to r co n s tr ic to r ap p eared not to
follow p a s s iv e ly , but com pelled the anim al to seek h igher am bient
tem pera tu res to f a c i l i ta te d ig e s t io n .
The mean preferred body tem perature s e le c te d by C onstric to r
c o n s tr ic to r in th is s tudy of 2.6.8 °C can be compared to 30 °C reported
by Brattstrom (1965). M cG innis and Moore (1969) show ed th a t juven ile ,
boa c o n s tr ic to rs had mean preferred body tem pera tu res of around 30 °C
in outdoor e n c lo su re s in San B ia s , M ex ico , The mean preferred tem
pera tu res of th ree a d u lts in a phototherm al cham ber w ere 2 2 .6 , 23 .1 ,
and 2 3 .7 . The th re e -d a y mean body tem perature of a f re e - l iv in g adu lt
boa m easured by rad io -te lem etry w a s 2 6 .4 . Carpet py thons M orelia
sp i lo te s have a preferred body tem perature of 30 °C in th e f ie ld and
in confinem ent (Webb and H eatw ole 1971). Cogger and Holm es (1960)
reported a preferred body tem perature for th is s p e c ie s of 34 ° C . S pec i
mens of Boa co n s tr ic to r found in the f ie ld in Sonora, M exico had
2 2
body tem pera tu res ranging from 2 5 .4 °C to 3 0 .4 0 C (Myres and Ells
1968).
, Although a con tinuous hea t source w as a v a i la b le , the an im als
vo lun ta ri ly ch o se to vary th e ir tem perature ra ther th an rem ain a t a
c o n s ta n t e le v a te d body tem pera tu re . This supports Regal.'s (1966)
finding th a t the l iza rd Klauberina r iv e rs ia n a may prefer ra ther than
simply to le ra te low environm ental te m p e ra tu re s . Regal (1966) reported
a minimum body tem perature for the boa co n s tr ic to r of 31 °C a f te r
feeding . My re s u l t s in d ica te a much low er minimum tem pera tu re a f te r
f e e d in g , often below 26 ° C .
The d iurnal tem perature s e le c t io n by C o n s tr ic to r co n s tr ic to r i s
b e s t co rre la ted with ligh t and dark p e r io d s , ra ther th an time of fe e d in g .
The h ig h es t tem peratures s e le c te d and the in c re a se in th e s n a k e 's
a c t iv i ty during the la te evening and n igh t support the b e l ie f th a t
C o n s tr ic to r co n s tr ic to r is primarily a noc tu rna l s p e c ie s (McGinnis and
Moore 1969).
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24
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25
P e te r , E. T . ; N ico lo ff , D. M . ; S o s in , H . ; W alder , A. I . ; andW a g e n s te e n , O. H. 1962. R e la tionsh ips be tw een g a s tr ic blood flow and s e c re t io n . Fed . Proc . 2 1 : 264 .
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