31 AN ABNORMAL THORNBACK RAY RAJA CLAVATA
Trans. Suffolk Nat. Soc. 41 (2005)
AN ABNORMAL THORNBACK RAY RAJA CLAVATA WITH ADDITIONAL PECTORAL FINS
J. R. ELLIS
An abnormal thornback ray Raja clavata Linnaeus, 1758 was caught by long line on 9 March 2005 near the Shipwash Bank (south-east of Orford, at approximately 52º 01’N, 01º 39’E). The specimen was an immature male of 54 cm total length (36·5 cm disc width and 27 cm disc length), and weighed approximately 850 g. Two additional fins were present on the dorsal surface, each originating from the mid-line and lying on the right hand side of the fish (Figure 1a). The anterior additional fin was relatively large, and the more posterior additional fin smaller.
The distance between the tip of the snout and the origin of the base of the anterior additional fin was 12 cm, and the origin of the base was 27 mm behind the spiracles. The maximum length and width of the anterior additional
Figure 1: Abnormal thornback ray Raja clavata showing (a) the dorsal surface with the anterior additional fin (A1), posterior additional fin (A2), and (b) x-ray of the specimen showing the upper jaw or palatoquadrate (Pal), lower jaw or Meckel’s cartilage (Mec), pectoral radials (p.r.), branchial arches (Bra), pectoral girdle (Pec), vertebral column (Ver), proterygium (Pro), mesopterygium (Mes) and metapterygium (Met), and with the approximate position of the additional fins marked.
Figure 1a Figure 1b
Trans. Suffolk Nat. Soc. 41 (2005)
Suffolk Natural History, Vol. 41 32
Def
orm
ity
Sp
ecie
s L
ength
W
idth
S
ex
Dat
e L
oca
tion
Ref
eren
ce
Th
ree
add
itio
nal
fin
s (6
, 9 a
nd
13
cm
in
le
ng
th)
on
d
ors
al
surf
ace,
sli
gh
tly
to t
he
rig
ht
of
the
mid
-lin
e
Dip
turu
s b
ati
s 8
4 c
m
- M
-
Aber
dee
n
Ren
nie
(1906
)
Ad
dit
ion
al
pec
tora
l fi
n
(9
cm
lon
g)
on
mid
-lin
e, l
yin
g t
o t
he
rig
ht
Dip
turu
s b
ati
s -
- -
- A
ber
dee
n
Ren
nie
(1906
)
Ad
dit
ion
al
pa
ir
of
fin
s as
soci
ated
w
ith
th
e b
ran
chia
l
arch
es a
nd
pec
tora
l g
ird
le o
n t
he
ven
tral
su
rfac
e
Leu
cora
ja c
ircu
lari
s -
47·5
cm
M
-
Nort
h S
ea
Har
per
(1933
)
Ad
dit
ion
al
pa
ir
of
fin
s as
soci
ated
w
ith
th
e b
ran
chia
l
arch
es o
n t
he
ven
tral
su
rfac
e
Leu
cora
ja c
ircu
lari
s 7
5 c
m
46
cm
M
-
NE
Shet
lan
d
Isle
s D
u B
uit
(1978)
Ad
dit
ion
al
fin
on
th
e d
ors
al
surf
ace,
lyin
g t
o t
he
rig
ht
Leu
cora
ja n
aev
us
- -
- -
Cel
tic
Sea
D
u B
uit
(1978)
An
ad
dit
ion
al f
in (
11
cm
hig
h)
on
the
left
w
ing
, cl
ose
to
th
e
scap
ula
Ra
ja c
lava
ta
91 c
m
- F
1845
Norm
andy
Des
long
cham
ps
(1853)
Ad
dit
ion
al
fin
as
soci
ated
w
ith
the
scap
ula
an
d
lyin
g
on
th
e
rig
ht
han
d
sid
e o
f th
e d
ors
al
surf
ace
Ra
ja c
lava
ta
- -
- -
Cel
tic
Sea
D
u B
uit
(1978)
Ta
ble
1:
Det
ail
s of
ska
tes
(Ra
jid
ae)
rec
ord
ed i
n N
ort
h-w
est
Eu
rop
ean
sea
s w
ith
ad
dit
ion
al
fin
s p
rese
nt
33 AN ABNORMAL THORNBACK RAY RAJA CLAVATA
Trans. Suffolk Nat. Soc. 41 (2005)
Tab
le 1
. C
on
tin
ued
Def
orm
ity
Sp
ecie
s L
ength
W
idth
S
ex
Dat
e L
oca
tion
Ref
eren
ce
Ad
dit
ion
al fi
n ar
isin
g fr
om
th
e
mid
lin
e on
th
e dors
al
surf
ace,
as
soci
ated
wit
h t
he
scap
ula
, an
d
lyin
g t
o t
he
rig
ht
Ra
ja c
lava
ta
- -
- -
- S
chnak
enbec
k
(1942)
Ad
dit
ion
al
fin
(7·5
cm
h
igh
) ly
ing
to t
he
rig
ht
of
the
mid
lin
e R
aja
cla
vata
49 c
m
35 c
m
- -
Co K
erry
H
illi
s (1
966)
Ad
dit
ion
al
fin
on
th
e d
ors
al
mid
lin
e p
ost
erio
r to
th
e h
ead
an
d
lyin
g t
o t
he
left
Ra
ja c
lava
ta
- 4
2 c
m
F
- A
ngle
sey
Gro
ve
and R
ober
ts
(1982)
Ad
dit
ion
al f
in (
2·2
cm
hig
h)
on
th
e d
ors
al
surf
ace
lyin
g
to
the
left
Ra
ja c
lava
ta
16·5
cm
11·1
cm
F
A
pr
1994
Sw
anse
a E
llis
(u
npubli
shed
)
Ad
dit
ion
al f
ins
lyin
g t
o t
he
rig
ht
of
the
mid
-lin
e on
th
e d
ors
al
surf
ace
Ra
ja c
lava
ta
54 c
m
36·5
cm
M
M
ar 2
005
South
ern
Nort
h S
ea
This
stu
dy
Sm
all
(5–6
cm
) ad
dit
ion
al p
ec-
tora
l fi
n
pro
ject
ing
fr
om
th
e
rig
ht
sid
e of
the
pec
tora
l g
ird
le
on t
he
ven
tral
su
rfac
e
Ra
ja m
on
tag
ui
- 2
4 c
m
- Ja
n 1
917
Gre
at O
rme
Johnst
one
(1920)
Trans. Suffolk Nat. Soc. 41 (2005)
Suffolk Natural History, Vol. 41 34
Sp
ecie
s L
eng
th
Wid
th
Sex
D
ate
Loca
tion
Ref
eren
ce
Pec
tora
l fi
ns
not
fuse
d t
o h
ead
Am
bly
raja
ra
dia
ta
63
cm
-
M
Nov 1
958
New
foundla
nd
Tem
ple
man
(1965)
Leu
cora
ja s
pp.*
-
- M
S
ep 1
909
Aber
dee
n
Wil
liam
son
(1911)
Ra
ja a
steri
as
- -
F
Nov 1
886
- B
ure
au (
18
89)
Ra
ja b
rach
yura
1
2 c
m
8 c
m
- A
pr
1934
Conca
rnea
u
Leg
endre
(1935)
Ra
ja b
rach
yura
4
1·5
cm
-
M
1943
La
Roch
elle
L
etac
onnou
x (
1949)
Ra
ja c
lava
ta
- 1
1 c
m
- S
ep 1
905
Bla
ckp
ool
Johnst
one
(1906)
Ra
ja c
lava
ta
- 6
0 c
m
M
- -
Vai
llan
t (1
908)
Ra
ja c
lava
ta
- 4
7.5
cm
F
-
- W
illi
amso
n (
1911)
Ra
ja c
lava
ta
- 4
6 c
m
F
- -
Wil
liam
son
(1911)
Ra
ja c
lava
ta
- 5
1 c
m
M
Feb
1930
Off
Ply
mouth
F
ord
(1930
)
Ra
ja c
lava
ta
72·8
cm
5
1·4
cm
M
A
ug 1
963
Conca
rnea
u
Du B
uit
(1
964)
Ra
ja c
lava
ta
- -
- -
Conca
rnea
u
Du B
uit
(1
978)
Pec
tora
l fi
ns
not
fuse
d t
o h
ead
(ri
gh
t si
de o
nly
)
Ra
ja m
icro
ocell
ata
-
26
cm
F
Ja
n 1
928
Off
Ply
mouth
F
ord
(1930
) R
aja
ra
du
la
54
cm
3
7 c
m
M
Mar
1975
Gulf
of
Tunis
C
apap
é an
d
Pan
toust
ier
(197
5)
Ro
stro
raja
alb
a
26
cm
1
8·5
cm
-
- A
dri
atic
D
’Anco
na
(1933
)
Pec
tora
l fi
ns
not
fuse
d t
o h
ead
an
d f
lesh
y l
ob
es b
etw
een
an
teri
or
marg
ins
of
pec
tora
l fi
ns
an
d h
ead
* E
ith
er L
. n
aevu
s or
L. fu
llo
nic
a
Ta
ble
2:
Det
ail
s of
ab
norm
al sk
ate
s (R
aji
da
e) w
ith
oth
er d
eform
itie
s of
the
pec
tora
l fi
ns.
35 AN ABNORMAL THORNBACK RAY RAJA CLAVATA
Trans. Suffolk Nat. Soc. 41 (2005)
fin were 91 mm and 60 mm respectively, and the base of this fin was 28 mm. The posterior additional fin was approximately 10 mm behind the anterior fin. The maximum length and width of the posterior additional fin were 39 mm and 25 mm respectively, and the base of this fin was 17 mm.
Both additional fins were pigmented on both sides, but paler towards the margins, and the skin was spinulose, although smoother nearer the margins. The anterior additional fin had several associated thorns, including median thorns posterior and anterior to the base, a well-developed thorn on the innermost part of the fin, and three spines on the lower posterior margin. The smaller of the additional fins had a median thorn near the base.
Cartilaginous radial elements were present in both additional fins, and were well developed in the more anterior fin. The large size and structure of the anterior fin, including the presence of a well-developed thorn, suggest that this was an additional pectoral fin, and the x-ray of the specimen (Figure 1b) confirmed that this fin was associated with the pectoral girdle. The pectoral girdle on the specimen was not symmetrical, and the connection between the pectoral girdle and metapterygium on the right hand side of the fish was malformed.
There are occasional reports of additional fins in skates (Table 1), including common skate Dipturus batis (Linneus, 1758) (Rennie, 1906), sandy ray Leucoraja circularis (Couch, 1838) (Harper, 1933; Du Buit, 1978), cuckoo ray L. naevus (Müller & Henle, 1841) (Du Buit, 1978), spotted ray Raja montagui Fowler, 1910 (Johnstone, 1920) and R. clavata (Deslongchamps, 1853; Schnakenbeck, 1942; Hillis, 1966; Grove and Roberts, 1982). Interestingly, in the majority of these reports, the additional fin lies on the right hand side of the fish.
Several other forms of abnormal development have been reported in skates and rays, though most of these reported abnormalities relate to specimens where the pectoral fins are not fully fused to the head, and these deformities have been reported in a range of batoids, including skates (summarised in Table 2), and sting and eagle rays (e.g. Chhapgar, 1964; Bennet, 1964; Easwaran, 1967). Other types of abnormality that have been observed in batoids include two-headed embryos (Lazarus, 1985), specimens with “extra snouts” (McIntosh, 1886), specimens where the rostral cartilage has not extended anteriorly, thus resulting in a blunt-snouted condition (Templeman, 1965), spinal deformities, particularly with regards the tail (Ford, 1930, Templeman, 1965; Du Buit, 1978), albinism and partial albinism (Wilson, 1951; Capapé and Pantoustier, 1975), abnormal dentition (Gudger, 1933), spinulose skin (Du Buit, 1978) and intersexuality and hermpahroditism (Quignard and Negla, 1971; Quignard and Capapé, 1972).
Though there are occasional reports of additional fins in skates, reports of additional fins in teleost fishes tend to be rare (Dawson, 1964, 1966, 1971; Venkateswarlu, 1972; Singh and Reddy, 1989; Raadik, 1993), though this is not surprising given that malformed larval stages are likely to have high mortality. In contrast, skates are oviparous and the embryo develops over a period of several months prior to hatching, with recently hatched fish relatively well developed. This may result in malformed skates having a greater chance of surviving after hatching.
Trans. Suffolk Nat. Soc. 41 (2005)
Suffolk Natural History, Vol. 41 36
Acknowledgements Thanks to Pete Draper (SFI, Lowestoft) for passing on information regarding the specimen, Bernard Seret (Muséum National d’Histoire Naturelle, Paris) for providing information from early references, and Wangford Veterinary Clinic for providing the X-ray.
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Jim Ellis CEFAS Lowestoft Laboratory Pakefield Road Lowestoft Suffolk NR33 0HT