429
land to restore urea that is continuously lost to the sea faster than it can be generated
metabolically (Gordon and Tucker 1968 ).
The mechanism responsible for reduced evaporative water loss in F. cancrivora
is unknown. The only mechanism known to provide for reduced evaporative water
loss in frogs in a given environment other than through cranial co-ossifi cation or
cocoon formation (see for review Wygoda et al. 2011 ) is by lipid secretion onto the
skin surface from lipid glands or lipid-secreting mucous glands (reviewed by
Lillywhite 2006 ). The histology of F. cancrivora skin has been examined and was
found to be unique among amphibians in having (in addition to mucous glands) two
previously undescribed glands (vacuolated and mixed) and no granular glands (Seki
et al. 1995 ). Because Seki et al. ( 1995 ) did not stain their skin samples for lipids, it
is not known whether any of these gland types are lipid sources. Further examination of F. cancrivora skin might help elucidate the mechanism that provides this
species with its low level of resistance to evaporative water loss.
Sucking Disk The fi sh species termed Echeneis naucrates and known as the sharksucker was originally described by Linnaeus in 1758. The genus name, Echeneis , is
derived from the Greek ‘ echein ’ meaning to hold and ‘nays’ meaning ship; suckling
fi sh, or remora (see for review Richards 2006 ). In ancient time, Greek sailors
believed in mysterious magical powers of sharksuckers which could slow down or
even stop their ships.
Transportation of one organism by another, phenomenon known as phoresy,
is related to characteristic behavioural features of remoras, which usually can be
observed on large fi sh species like swordfi sh or tuna, or even, in the case of
small specimens, traveling in the mouths or gills of large manta rays, sailfi sh, and
ocean sunfi sh.
After the young remoras are about 1 cm long, the sucking disc became visible
and is fully formed when the fi sh reaches about 3 cm. In adult forms, the sucking
disc is well visible due to a series of paired, transversely oriented, “ pectinated
lamellae ” which forms the most conspicuous structure on the surface of dorsoventrally fl attened head. The pair of pectinated lamellae together with the interneural
ray and intercalary bone represent the skeleton of the sucking disc (Bonnell 1962 ).
“The main part of each pectinated lamella is formed by bilateral extensions of the
base of the fi n spine just above its proximal tip, each of which develops a row of
spinous projections, or spinules, along its posterior margin. The number of rows and
the number of spinules increase with size, and they become autogenous from the
body of the lamellae,” (Britz and Johnson 2012 ) (Fig. 14.4 ). The spino-occipital and
anterior spinal nerves are responsible for innervation of the muscles and the skin of
the disc that is originally belonged to the anterior region of the trunk (Houy 1910 ).
“A series of lateral line nerve innervated sense organs at the rim of the disk’s suction
cup are similar in structure to Meissner’s corpuscles in mammals, sensitive to touch,
and play an important role during the attachment of the remora. The remarkable
behaviour of remoras to attach to large animals in the water has led to a similarly
fascinating, but true, use of remoras for catching fi sh and turtles. This is only possible
because of the great force that is needed to dislodge a remora once it has attached”
(Britz and Johnson 2012 ; see also Fulcher and Motta 2006 ).
14 Epilogue
land to restore urea that is continuously lost to the sea faster than it can be generated
metabolically (Gordon and Tucker 1968 ).
The mechanism responsible for reduced evaporative water loss in F. cancrivora
is unknown. The only mechanism known to provide for reduced evaporative water
loss in frogs in a given environment other than through cranial co-ossifi cation or
cocoon formation (see for review Wygoda et al. 2011 ) is by lipid secretion onto the
skin surface from lipid glands or lipid-secreting mucous glands (reviewed by
Lillywhite 2006 ). The histology of F. cancrivora skin has been examined and was
found to be unique among amphibians in having (in addition to mucous glands) two
previously undescribed glands (vacuolated and mixed) and no granular glands (Seki
et al. 1995 ). Because Seki et al. ( 1995 ) did not stain their skin samples for lipids, it
is not known whether any of these gland types are lipid sources. Further examination of F. cancrivora skin might help elucidate the mechanism that provides this
species with its low level of resistance to evaporative water loss.
Sucking Disk The fi sh species termed Echeneis naucrates and known as the sharksucker was originally described by Linnaeus in 1758. The genus name, Echeneis , is
derived from the Greek ‘ echein ’ meaning to hold and ‘nays’ meaning ship; suckling
fi sh, or remora (see for review Richards 2006 ). In ancient time, Greek sailors
believed in mysterious magical powers of sharksuckers which could slow down or
even stop their ships.
Transportation of one organism by another, phenomenon known as phoresy,
is related to characteristic behavioural features of remoras, which usually can be
observed on large fi sh species like swordfi sh or tuna, or even, in the case of
small specimens, traveling in the mouths or gills of large manta rays, sailfi sh, and
ocean sunfi sh.
After the young remoras are about 1 cm long, the sucking disc became visible
and is fully formed when the fi sh reaches about 3 cm. In adult forms, the sucking
disc is well visible due to a series of paired, transversely oriented, “ pectinated
lamellae ” which forms the most conspicuous structure on the surface of dorsoventrally fl attened head. The pair of pectinated lamellae together with the interneural
ray and intercalary bone represent the skeleton of the sucking disc (Bonnell 1962 ).
“The main part of each pectinated lamella is formed by bilateral extensions of the
base of the fi n spine just above its proximal tip, each of which develops a row of
spinous projections, or spinules, along its posterior margin. The number of rows and
the number of spinules increase with size, and they become autogenous from the
body of the lamellae,” (Britz and Johnson 2012 ) (Fig. 14.4 ). The spino-occipital and
anterior spinal nerves are responsible for innervation of the muscles and the skin of
the disc that is originally belonged to the anterior region of the trunk (Houy 1910 ).
“A series of lateral line nerve innervated sense organs at the rim of the disk’s suction
cup are similar in structure to Meissner’s corpuscles in mammals, sensitive to touch,
and play an important role during the attachment of the remora. The remarkable
behaviour of remoras to attach to large animals in the water has led to a similarly
fascinating, but true, use of remoras for catching fi sh and turtles. This is only possible
because of the great force that is needed to dislodge a remora once it has attached”
(Britz and Johnson 2012 ; see also Fulcher and Motta 2006 ).
14 Epilogue