In e eb a e Zoology, 2024, 21(1): 58–66 © INVERTEBRATE ZOOLOGY, 2024
The shape o sucke ing ee h in he hec oco ylized pa
o kisslip cu le ish (Sepia lycidas)
A. Omu a1*, N. Masaki2, I. Oh a3
1 Design Cou se, Nihon Uni e si y College o A , 2-42-1, Asahigaoka, Ne ima-ku, Tokyo, Japan.
2 Hamama su BioPho onics Inno a ion Chai , Hamama su Uni e si y School o Medicine, 1-20-1,
Handayama, Higashi-ku, Hamama su, Shizuoka, Japan.
3 Ul as uc ual Analysis, Ad anced Resea ch Facili ies and Se ices, Hamama su Uni e si y School
o Medicine, 1-20-1, Handayama, Higashi-ku, Hamama su, Shizuoka, Japan.
* Co esponding au ho : [email p o ec ed]
Ayano Omu a: ORCID 0000-0002-2986-5265
No i aka Masaki: ORCID 0000-0002-4624-4727
ABSTRACT: Decapodi o m cephalopods ha e ‘sucke ing ee h’ in he sucke s o hei
a ms and en acles. The sucke ing ee h a e ha d s uc u es, and hei shape is ela ed o
hei unc ion; o example, he sucke ing ee h on he a m a e long and sha p, aiding in
p ey cap u e.
Among decapodi o m cephalopods, cu le ish ha e small sucke s on hei hec oco ylus,
in addi ion o hei a ms and en acles. The hec oco ylus, a modi ied (hec oco ylized) a m
p esen in male cephalopods, is speci ically mo phologically adap ed o g asping and
ans e ing a ba ch o spe ma opho es o emales du ing ma ing. The e o e, unde s and-
ing he shape o he hec oco ylus is c ucial o comp ehending he ma ing beha io and
ep oduc i e s a egy o cephalopods. Howe e , he mo phology o he sucke ing ee h
on he hec oco ylus in cu le ish emains unknown.
He e, we epo he mo phological ea u es o he sucke ing ee h on he hec oco ylized
pa o Sepia lycidas. We examined and quan i ied he ee h o he sucke ing using ield
emission scanning elec on mic oscopy (FE-SEM) and compa ed he shape o he sucke
ee h on he hec oco ylus wi h hose on he egula a m. The ee h on he hec oco ylized
pa we e sho e and mo e ob use compa ed o hose on he a m, and he e we e li le di -
e ences in ee h shape by posi ion on he ing ci cum e ence. In con as , he ee h on he
a m we e longe and sha pe , and hei leng h and sha pness a ied be ween he o al and
abo al sides. Possible causes o he mo phological ea u es o hec oco ylized sucke s in
ma ing beha io a e discussed; we sugges ha he sho e and mo e ob use sucke ee h
a ound he ci cum e ence o hec oco ylized pa would be op imized o a oid damaging
he spe ma opho es and o e icien ly ans e hem o he emale. This esul con ibu es o
unde s anding he basic mo phology o he hec oco ylus and ma ing s a egy o cu le ish.
How o ci e his a icle: Omu a A., Masaki N., Oh a I. 2024. The shape o sucke ing ee h
in he hec oco ylized pa o kisslip cu le ish (Sepia lycidas) // In e . Zool. Vol.21. No.1.
P.58–66. doi: 10.15298/in e zool.21.1.02
KEY WORDS: cu le ish, Decapodi o ms, hec oco ylus, Mollusca, sucke , sucke ing ee h.
Форма зубцов присосок гектокотилизированных рук
у каракатицы Sepia lycidas
А. Омура1*, Н. Масаки2, И. Охта3
1 Design Cou se, Nihon Uni e si y College o A , 2-42-1, Asahigaoka, Ne ima-ku, Tokyo, Japan.
2 Hamama su BioPho onics Inno a ion Chai , Hamama su Uni e si y School o Medicine, 1-20-1,
Handayama, Higashi-ku, Hamama su, Shizuoka, Japan.
The sucke ee h o he hec oco ylus o kisslip cu le ish 59
In oduc ion
Cephalopod ma ing beha io is e y unique
as i is ca ied ou using a modi ied a m. Mos
male cephalopods ha e a modi ied a m called
he hec oco ylus, which is used o ans e ing
a ba ch o spe ma opho es o emales (D ew,
1911; Squi es e al., 2013; Hanlon, Messenge ,
2018; Ibáñez e al., 2019). The hec oco ylus was
i s desc ibed in A is o le’s wo k. The name
hec oco ylus was gi en by Geo ge Cu ie , who
ini ially conside ed i a pa asi ic wo m and ga e
i a gene ic name by combining ‘hund ed’ and
‘hollow hing’ in 1829 (Tompson, 1913).
The shape o he hec oco ylus ( he modi ied
pa is called he hec oco ylized pa ) is speci ic
and unique o he males o each species (Nixon,
Yonge, 2003; Oku ani, 2010). Fo example,
he hec oco ylus in males o Eup ymna mo sei
(Ve ill, 1881) is g ea ly modi ied, wi h leshy
papillae o med om enla ged and elonga ed
swollen sucke pedicels (Raid e al., 2005), and
he hec oco ylus o Loligo o besii (S eens up,
1857) males has i s sucke pedicel modi ied in o
long papillae, which g adually dec ease in size
dis ally (Raid e al., 2005). These modi ied shapes
a e conside ed e ec i e o g asping a ba ch o
spe ma opho es and ans e ing hem o he
emale (Oku ani, 2010). The e o e, knowledge
o he hec oco ylus’s mo phology is impo an
o unde s and hei ma ing s a egy.
In mos membe s o he amily Sepiidae
(cu le ish), he hec oco ylized pa has been
desc ibed as ha ing ‘smalle ’ o ‘ educed’
sucke s compa ed o he o he a ms (Raid e
al., 2005; Na eewa hana, 2008). Howe e , he
3 Ul as uc ual Analysis, Ad anced Resea ch Facili ies and Se ices, Hamama su Uni e si y School
o Medicine, 1-20-1, Handayama, Higashi-ku, Hamama su, Shizuoka, Japan.
* Автор для корреспонденции: [email p o ec ed]
РЕЗЮМЕ: У десятируких головоногих моллюсков на роговых кольцах присосок рук
имеются зубцы. Зубцы на присосках — твердые структуры, форма которых связана с
их функцией; например, зубцы на присоске руки длинные и острые, что помогает за-
хватывать добычу. У каракатиц, относящихся к десятируким головоногим моллюскам,
имеются небольшие присоски не только на руках и щупальцах, но и на гектокотиле.
Гектокотиль — присущая самцам головоногих модифицированная (гектокотилизиро-
ванная) рука — морфологически приспособлен для захвата и передачи сперматофора
самке во время спаривания. Поэтому изучение формы гектокотиля имеет решающее
значение для понимания брачного поведения и репродуктивной стратегии головоногих
моллюсков. Однако морфология зубцов кольца присоски на гектокотиле у каракатиц
до сих пор не выяснена.
В данной работе мы рассматриваем морфологические особенности зубцов присоски
на гектокотиле Sepia lycidas. Мы изучили и количественно оценили зубцы присоски с
помощью эмиссионной сканирующей электронной микроскопии (FE-SEM) и сравнили
форму зубцов присоски на гектокотиле с зубцами на обычной руке. Зубцы присосок
гектокотиля оказались короче и тупее по сравнению с зубцами на руке, а различия в
форме зубцов в зависимости от положения по окружности кольца незначительными.
Напротив, зубцы на руке оказались длиннее и острее, причем их длина и острота
различались на оральной и аборальной сторонах. Обсуждаются возможные причины
влияния морфологических особенностей гектокотилизированных присосок на брач-
ное поведение. Мы предполагаем, что более короткие и тупые зубцы по окружности
присоски гектокотилизированной руки специализированы для того, чтобы не по-
вреждать сперматофоры и эффективно передавать их самке. Эти данные вносят вклад
в понимание базовой морфологии гектокотиля и стратегии спаривания каракатиц.
Как цитировать эту статью: Omu a A., Masaki N., Oh a I. 2024. The shape o sucke ing
ee h in he hec oco ylized pa o kisslip cu le ish (Sepia lycidas) // In e . Zool. Vol.21.
No.1. P.58–66. doi: 10.15298/in e zool.21.1.02
КЛЮЧЕВЫЕ СЛОВА: каракатицы, Decapodi o ms, гектокотиль, Mollusca, присоски,
зубцы присоски.
A. Omu a e al.
60
Fig. 1. Diag am o he hec oco ylus (le a m) and he a m ( igh a m) o Sepia lycidas (modi ied om Sasaki,
1929). A — hec oco ylus; B — a m. The ed squa e shows ou sucke s ha we e obse ed wi h he scanning
elec on mic oscope. The hec oco ylus has a hec oco ylized pa a i s base. The e a e small sucke s on he
hec oco ylized pa .
Рис. 1. Схема гектокотиля (левой руки) и руки (правой руки) Sepia lycidas (по Sasaki, 1929, с измене-
ниями). A — гектокотиль; B — рука. Красным прямоугольником показаны четыре присоски, которые
были исследованы с помощью сканирующего электронного микроскопа. В основании гектокотиля
имеется гектокотилизированная часть. На гектокотилизированной части имеются небольшие присоски.
mo e de ailed mo phology o he sucke on he
hec oco ylized pa (hec oco ylized sucke ) o
Sepiidae is no well unde s ood.
In pa icula , he shape o he sucke ing
ee h is impo an o unde s anding i s unc ion.
In gene al, a decapodi o mes’ sucke has sucke
ing ee h (Nixon, Dilly, 1977; San i, G aziadei,
1975; Tsuchiya, 2013), which a e ha d s uc u es
assembled om a p o ein amily called ‘suck-
e ins’ (Hiew, Mise ez, 2017). A sucke ing has
many sucke ee h on i s ci cum e ence. The
shapes o he sucke ee h on bo h he a m and
The sucke ee h o he hec oco ylus o kisslip cu le ish 61
Fig. 2. The cu a u e adius o a sucke oo h used o quan i ying he sucke oo h sha pness. I co esponds o
he adius o a ci cle wi h he same cu e as he a c. A — a s eepe cu e (sha pe oo h) ha shows a smalle
cu a u e adius; B — a gen le cu e (mo e ob use oo h) ha shows a la ge cu a u e adius.
Abb e ia ion: — cu a u e adius.
Рис. 2. Радиус кривизны зубца присоски, используемый для количественной оценки остроты зубца
присоски. Он соответствует радиусу окружности с той же кривизной, что и дуга. A — более крутая
кривая (более острый зуб), которой соответствует меньший радиус кривизны; B — более пологая
кривая (более тупой зуб), которой соответствует больший радиус кривизны.
Обозначения: — радиус кривизны.
en acle a e ela ed o hei hun ing unc ion: he
sucke ing ee h on he a m, which a e mainly
used o hold p ey and ans e i o he mou h
du ing ea ing, a e sha pe han he ee h ings on
he en acle, whose main pu pose is o ca ch and
e ac p ey du ing hun ing (Nixon, Dilly, 1977;
Nixon, Yong, 2003). Howe e , o he bes o ou
knowledge, he shape o he sucke ing ee h on
he hec oco ylized pa (hec oco ylized sucke )
o Sepiidae emains un e ealed.
He e, we epo he mo phological ea u es
o he sucke ing ee h o he hec oco ylized
sucke in Sepiidae. We compa ed he leng h and
sha pness o he sucke ee h on he hec oco yl-
ized sucke wi h hose on he co esponding a m.
Ma e ial and me hods
SPECIMENS. We used adul males o kisslip
cu le ish (Sepia lycidas G ay, 1849) (n = 4, Man le
leng h we e 21.5, 22.5, 23.4, 28.1 cm, espec i ely).
F esh ishe ies specimens we e pu chased a Washizu
Po (Shizuoka, Japan) a hei b eeding in May 2017,
which is hei b eeding season (Ap il o July in Japan;
Na suka i, Tashi o (1991)). Since male Sepiidae
de elop hei hec oco ylus o ma ing beha io on-
ogene ically, we used specimens du ing his season
o obse e he mo phology ac ually u ilized in ma ing
beha io .
The hec oco ylized pa o he le a m IV and he
co esponding si e on he igh a m we e ampu a ed
and p e- ixed o e nigh in 2% glu a aldehyde (TAAB,
Be kshi e, UK) in DPBS (Dulbecco’s phospha e
bu e saline; Sigma-Ald ich, MO, USA) a 4C. The
specimens we e hen insed se e al imes in DPBS,
pos - ixed o 2 h in 1% osmium e oxide (Nisshin
EM, Tokyo, Japan) in he same bu e a oom em-
pe a u e, dehyd a ed hough a g aded se ies o e hanol
solu ions, a e subs i u ion o e hanol wi h -bu yl
alcohol and imme sed in 100% -bu yl alcohol h ee
imes a 37C. Then he specimens we e eeze-d ied
(JFD300; JEOL, Tokyo, Japan) o o e nigh a 2C.
D ied specimens we e coa ed wi h osmium using
an osmium plasma coa e (HPC-1SW; VACUUM
DEVICE, Mi o, Japan).
We ha e analyzed ou sucke s on he middle
o hec oco ylized pa (le a m IV) (Fig. 1A) and
he co esponding si e on he igh a m IV (Fig. 1B)
o each indi idual (i.e., a o al eigh o sucke s o
each indi idual) o obse a ion and quan i ica ion
as below.
OBSERVATION OF THE SUCKER RING
TEETH. To unde s and o obse ing su ace ine
s uc u e a high esolu ion o he hec oco ylized
sucke s, we compa ed he s uc u es o hec oco ylus
and a m sucke s by Field Emission Scanning Elec on
Mic oscopy (FE-SEM) a Hamama su Uni e si y
o School o Medicine (Shizuoka, Japan). Hi achi
S-4800 Field Emission Scanning Elec on Mic oscope
(Hi achi, Tokyo, Japan) was used o pe o m FE-SEM
obse a ions and ope a ed a an accele a ion ol age o
5.0 kV. The accum le el o he obse a ion chambe
was 10–3 o 10–7 Pa. The de ec o o seconda y elec-
ons was a mix u e o signals om uppe and lowe
A. Omu a e al.
62
Fig. 3. Diag am o he sucke . The sucke consis s o he sucke ing ee h (ha d pa ) su ounded by he im (so
pa ). Sucke oo h leng h is he dis ance be ween he base o he sucke oo h and he ip o he sucke oo h.
Рис. 3. Схема присоски. Присоска состоит из зубчатого кольца (твердая часть), окруженного ободком
(мягкая часть). Длина зубца присоски — это расстояние между основанием и вершиной зубца.
de ec o s. The ollowing expe imen al pa ame e s
we e used: wo king dis ance, 30 mm; ape u e size,100
mm; and scan speed, 10 o 15 ames/s. These whole
p ocesses we e done a Hamama su Uni e si y o
School o Medicine (Shizuoka, Japan).
MORPHOLOGICAL QUANTIFICATION OF
THE SUCKER AND SUCKER RING TEETH. To
examine he mo phological ea u es o he sucke s on
he hec oco ylized pa , we quan i a i ely compa ed
he sucke s on he hec oco ylus and he a m. We used
ou sucke s on he middle o hec oco ylized pa (le
a m IV) (Fig. 1A) and he co esponding si e on he
igh a m IV (Fig. 1B) o each indi idual (i.e., a o al
eigh o sucke s o each indi idual). We quan i ied
i e sucke ee h on each side.
Fi s , we quan i ied he leng h o he sucke oo h
and he sha pness o he sucke oo h on bo h he o al
and abo al sides. The leng h o he sucke oo h was
measu ed om acqui ed SEM images using Adobe
Pho oshop CS5 so wa e. He e, we de ined he leng h
o he sucke oo h as he dis ance be ween he base o
he sucke oo h and he ip o he sucke oo h (Fig.
2). The leng h o he sucke oo h was s anda dized
agains he leng h o he do sal man le. We measu ed
he cu a u e adius o he oo h ips as he sha pness
o he sucke ee h (Fig. 3). Since he ips o he sucke
oo h a e no exac ly poin ed, we used he cu a u e
adius ins ead o he angle o quan i y he sha pness
o he sucke oo h. The cu a u e adius co esponds
o he adius o a ci cle wi h he same cu e as he
a c. A s eepe cu e (sha pe ee h) shows a smalle
cu a u e adius (Fig. 3A), while a gen le cu e
(mo e ob use ee h) shows a la ge cu a u e adius
(Fig. 3B). We conside ed he base- o-base dis ance
be ween ee h as a cu e and measu ed i s cu a u e
adius on SEM images using Adobe Illus a o CC
2019 so wa e.
Addi ionally, we measu ed he diame e o he
sucke s om SEM images (Fig. 2) using Adobe
Pho oshop CS5 so wa e.
The signi icance o he di e ences was s a is i-
cally compa ed using Welch’s - es wi h he s a is ical
compu ing so wa e R.
The sucke ee h o he hec oco ylus o kisslip cu le ish 63
Fig. 4. Scanning elec on mic oscope images o sucke s o Sepia lycidas. A — he sucke o he hec oco yl-
ized pa ; B — he sucke o he co esponding a m ( igh a m). The le images show he sucke s, and he
igh images show magni ied images o he sucke ing ee h. The uppe side is he abo al side, and he lowe
side is he o al side.
Рис. 4. Присоски Sepia lycidas, сканирующая электронная микроскопия (СЕМ). A — присоска гектоко-
тилизированной части; B — присоска соответствующей руки (правая рука). На левых изображениях
показаны присоски, а на правых — увеличенные изображения зубцов присоски. Верхняя сторона —
аборальная, нижняя — оральная.
Resul s
The shape o he sucke ee h di e ed be-
ween he hec oco ylus and he a m. The sucke
ee h o he hec oco ylus we e obse ed o be
sho e and mo e ob use in compa ison o hose
ound on he a m (Fig. 4). The leng h and sha p-
ness o he sucke ee h on he hec oco ylus did
no no iceably di e o e he en i e ci cum e -
ence (Fig. 4A). Mo eo e , no s a is ically sig-
ni ican di e ences we e de ec ed in he leng h
and sha pness o he sucke ee h be ween he
A. Omu a e al.
64
Fig. 5. Mo phological quan i ica ion o he sucke and sucke ing ee h. A — a e age leng h o he sucke
oo h on he o al and abo al sides o he hec oco ylus and he a m; B — a e age sha pness (cu a u e adius)
o he sucke oo h on he o al and abo al sides o he hec oco ylus and he a m; C — a e age diame e o
he sucke o he hec oco ylus and he a m. The e o ba ep esen s he s anda d de ia ion. Single as e isk
indica es p < 0.05, and double as e isk indica es p < 0.01.
Abb e ia ions: o — o al side; a — abo al side.
Рис. 5. Морфологическая количественная оценка присосок и зубцов присосок. A — средняя длина
зуба присоски на оральной и аборальной сторонах гектокотиля и руки; B — средняя острота (ради-
ус кривизны) зуба присоски на оральной и аборальной сторонах гектокотиля и руки; C — средний
диаметр присоски гектокотиля и руки. Диапазон погрешностей показывает стандартное отклонение.
Одиночная звездочка обозначает p < 0,05, двойная звездочка — p < 0,01.
Обозначения: o — оральная сторона; a — аборальная сторона.
The sucke ee h o he hec oco ylus o kisslip cu le ish 65
o al and abo al sides o he hec oco ylus (Fig.
5A, B).
In con as , he sucke ee h o he a m we e
longe and sha pe compa ed o hose o he
hec oco ylus (Fig. 4). Speci ically, he a m’s
o al side exhibi ed sho e and mo e ob use
ee h, whe eas he abo al side displayed longe
and sha pe ee h (Fig. 4B). These di e ences
we e s a is ically signi ican (Fig. 5A; a e age
leng h o he sucke oo h; o al side: 2.01 ±
0.85 [ ange] (a e age ± s anda d e o [ ange])
s. abo al side: 4.90 ± 1.42 [ ange]; - es , p <
0.05, Fig. 5B; a e age sha pness o he sucke
oo h; o al side: 0.06 ± 0.02 [ ange] (a e age ±
s anda d e o [ ange]) s. abo al side: 0.03 ±
0.02 [ ange]; - es , p < 0.05).
Fu he mo e, he diame e o he hec oco ylus
sucke s was no iceably smalle in compa ison
o hose o he a m (Fig. 4), a di e ence ha
p o ed o be s a is ically signi ican (Fig. 5C;
hec oco ylus: 1.45 ± 0.29 [ ange] (a e age ±
s anda d e o [ ange]) s. a m: 2.30 ± 0.36
[ ange]; - es , p < 0.01).”
Discussion
In his s udy, we i s epo ha he shape
o sucke ing ee h o he hec oco ylized pa
o S. lycidas di e s om ha o he a m sucke .
The o e all s uc u e was ypical o Sepiidae’s
sucke s; i had a so im enci cling he in un-
dibulum, wi hin which was a ing wi h sucke
ee h (Nixon, Young, 2003). As he shape o
sucke ing ee h is known o ha e a ela ion
o i s unc ion (Nixon, Dilly, 1977; Oku ani,
2010; Tsuchiya, 2013; Omu a, Ikeda, 2022),
he mo phological ea u es o he sucke ing
ee h o he hec oco ylus would be use ul o
ma ing beha io . Possible adap a ion s a egies
a e discussed below.
Fi s ly, he sho and ob use ea u es o he
sucke ee h a ound he en i e ci cum e ence
o he hec oco ylized pa would be sui able
o g asping spe ma opho es wi hou hooking
and sc a ching and o smoo hly ans e ing
hem o a emale. Gene ally, he sucke ee h o
decapodi o ms (including cu le ish) a e used
o ca ch p ey by hooking (Nixon, Dilly, 1977;
Oku ani, 2010; Tsuchiya, 2013; Omu a, Ikeda,
2022) and can damage p ey o an enemy (Ce ullo,
Rope , 2012). As o his hooking usage, he
sucke ee h o he con ol (non-hec oco ylized)
a m we e longe and sha pe han hose o he
hec oco ylized pa , and he ee h on he abo al
side a e longe and sha pe han hose on he o al
side (Figs 4, 5) o holding p ey and ans e ing
i o he mou h (Oku ani, 2010). Compa ing o
he longe and sha pe sucke ee h, sho e and
mo e ob use sucke ee h would no be sui able
o hooking. The hec oco ylus is used o g asp-
ing spe ma opho es and p essing hem agains
he emale du ing ma ing (Hanlon e al., 1999;
Wada e al., 2010). Fo his usage, he sucke ee h
o he hec oco ylus need o a oid hooking and
sc a ching in any di ec ion when he hec oco ylus
g asps he ba ch o spe ma opho es. The e o e,
he sho e and mo e ob use ea u es o he
sucke ee h a ound he en i e ci cum e ence o
he hec oco ylized pa would be bene icial o
g asping spe ma opho es wi hou damaging hem
and o smoo hly ans e ing hem o a emale.
Secondly, small-diame e sucke s wi hou
sha p hooking would enhance he hec oco ylus’
abili y o g asp spe ma opho es. In gene al, small
sucke s wi hou sha p hooking ac as a non-slip
s uc u e on a su ace, enabling hem o s ongly
g asp and manipula e he ba ch o spe ma o-
pho es e ec i ely; such a s uc u e appea s in a
non-slip glo e (Da id, 2002). Simila ly, small
sucke s on he hec oco ylized pa o S. lycidas
may aid in enhancing he con ol o g asping
and manipula ing spe ma opho es. The exis ence
o small sucke s on he hec oco ylized pa o
Sepiidae is consis en wi h he ea lie epo
abou he mac oana omy o S. lycidas (Sasaki,
1929) and o he species o cu le ish (Raid e al.,
2005; Na eewa hana, 2008).
We analyzed he mo phology o he sucke
ing ee h o he hec oco ylus o S. lycidas and
discussed hypo heses o mo phological adap a-
ions o ma ing beha io . Fu he in es iga ions
o he ma ing beha io o S. lycidas migh suppo
ou conclusions. Fi s , whe he he s uc u e o he
hec oco ylized sucke can g ip spe ma opho es
wi hou sc a ching hem should be s udied. The
i mness o spe ma opho es and g ipping o ce
o he hec oco ylus should be measu ed. Second,
e i ying whe he he hec oco ylized sucke
unc ions e ec i ely as an an i-slip de ice when
g ipping spe ma opho es is needed. Obse ing
he su ace s uc u e o spe ma opho es and
measu ing he ic ion and adhesion o ces o he
hec oco ylized sucke h ough expe imen al s ud-
ies should be conduc ed. This s udy con ibu es
A. Omu a e al.
66
o ou unde s anding o he basic mo phology
and ma ing s a egies o cu le ish.
Compliance wi h e hical s anda ds
CONFLICTS OF INTEREST: The au ho s decla e
ha hey ha e no con lic s o in e es .
Acknowledgemen s
We hank o Shige oshi Okazaki o p o iding
some eagen and le ing us use labo a o y. Takashi
Oku ani, and Tsunemi Kubode a o p o iding use ul
li e a u e on cu le ish. We hank Takano i Maeha a o
helping o keep specimens. We hank Jann Vende i,
Jona han Able , Kazuno i Hasegawa, and Masashi
Kimu a o gi ing use ul ad ice. This wo k was sup-
po ed by G an o Basic Science Resea ch P ojec s
om The Sumi omo Founda ion and Japan Socie y o
he P omo ion o Science KAKENHI (JP20K15605).
We also ex end ou g a i ude o he e iewe s o hei
me iculous e iews and aluable eedback.
Re e ences
Ce ullo M.M., Rope C.F.E. 2012. Gian squid: sea ching
o a sea mons e . Minneso a: Caps one P ess. 48 p.
Da id M.A. 2002. G ip-enhancing glo e // U. S. Pa .
US6427248 (B1).
D ew A.G. 1911. Sexual ac i i ies o he squid, Loligo pealii
(Les.) I. copula ion, egg-laying and e iliza ion // J.
Mo phol. Vol.22. P.327–359.
Hanlon R.T., Amen S.A., Gab H. 1999. Beha io al aspec s
o spe m compe i ion in cu le ish, Sepia o icinalis (Sepi-
oidea: Cephalopoda) // Ma . Biol. Vol.134. P.718–728.
Hanlon R.T., Messenge J.B. 2018. Cephalopod beha iou .
Camb idge uni . p ess. Camb idge. 376 p.
Hiew S.H., Mise ez A. 2017. Squid sucke ing ee h: mul-
iscale s uc u e–p ope y ela ionships, sequencing,
and p o ein enginee ing o a he moplas ic biopolyme
// ACS Bioma e . Sci. Eng. Vol.3. P.680–693.
Ibáñez C.M., Ja ie a P.Á., Jenni e C., Se gio A.C., Cecilia
M.P.G., En ico L.R. 2019. Sexual selec ion and he
e olu ion o male ep oduc i e ai s in ben hic oc opuses
// F on . Physiol. Vol.10. P.1–13.
Na eewa hana A. 2008. The Sepiidae (Cephalopoda) o
Thailand // Phuke Ma . Biol. Cen . Res. Bull. Vol.69.
P.25–41.
Na suka i Y., Tashi o M. 1991. Ne i ic squid esou ces and
cu le ish esou ces in Japan // Ma . F eshw. Beha .
Physiol. Vol.18. No.3. P.149–226.
Nixon M., Dilly P.N. 1977. Sucke su aces and p ey cap u e
// Symposium Zool. Soc. Lond. Vol.38. P.447–511.
Nixon M., Young J.Z. 2003. The b ains and li es o cepha-
lopods. Ox o d: Ox o d Uni . P ess. 406 p.
Oku ani T. 2010. [F esh decapodi o ms s udy]. Kanagawa:
Tokai Uni . P ess. 366 p [In Japanese, wi h English
summa y].
Omu a A., Ikeda Y. 2022. Mo phology o he sucke s o
hun ing beha io in b oadclub cu le ish (Sepia la ima-
nus) // Ecol. Res. Vol.37. P.156–162.
Raid A., Je eb P., Rope C.F.E. 2005. Cephalopod o he
wo ld; an anno a ed and illus a ed ca alogue o species
known o da e, chambe ed nau iluses and sepioids. FAO
species ca . ish. pu p. p ess. Cali o nia. 264 p.
San i P.A., G aziadei P.P.C. 1975. A ligh and elec on mic o-
scope s udy o in a-epi helial pu a i e mechano ecep o s
in squid sucke s // Tissue Cell. Vol.7. P.689–702.
Sasaki M. 1929. A monog aph o he dib anchia e cepha-
lopods o he Japanese and adjacen wa e s // J. Fac.
Ag ic. Hokkaido Uni . Vol.20. P.1–357.
Squi es Z.E., Ma k D.N., De i S.F. 2013. Ma ing beha iou
and gene al spawning pa e ns o he sou he n dumpling
squid Eup ymna asmanica (sepiolidae): a labo a o y
s udy // J. Mollusc. S ud. Vol.79. P.263–69.
S eens up J. 1857. Hec oco ylus o ma ion in A gonau a
and T emoc opus explained by obse a ions on simila
o ma ions in he cephalopoda in gene al // Ann. Mag.
Na . His . Vol.2. P.81–114.
Thompson D.W. 1913. On A is o le as a biologis : wi h a
p ooemion on He be Spence ; being he He be Spence
lec u e deli e ed be o e he uni e si y o Ox o d, on
Feb ua y 14, 1913. Ox o d: Ox o d Cla endon P ess. 36 p.
Tsuchiya K. 2013. [The esea ch o squid and oc opus].
Kyo o: PHP p ess. 63 p [in Japanese].
Ve ill A.E. 1881. The cephalopods o he no heas e n coas
o Ame ica. pa II. he smalle cephalopods, including
he “squids” and he oc opi, wi h o he allied o ms //
T ans. Conn. Acad. Vol.5. P.259–446.
Wada T., Takeshi T., Toh u M., Yu aka N. 2010. Spe m
emo al, ejacula ion, and hei beha iou al in e ac ion
in male cu le ish in esponse o emale ma ing his o y
// Anim. Beha . Vol.79. P.613–619.
Responsible edi o E.N. Teme e a
