Modification of pectoral fins occurs during the larva-to-juvenile transition in the mudskipper (Periophthalmus modestus)

Abstract

BackgroundMudskippers are amphibious fishes that use their pectoral fins to move on land. Their pectoral fins are specifically modified for terrestrial locomotion. Studies of the anatomy and kinematics of adult mudskippers suggest that modifications of the pectoral fins, such as their protrusion and elongation of the proximal radials, may provide greater control and flexibility in pectoral fin–based locomotion. However, it is unknown when and how the unique features of these pectoral fins form during the development of mudskippers, which begin life as a planktonic organism.ResultsHere we examined the developmental process of the pectoral fins of the mudskipper Periophthalmus modestus to address these questions. We also observed other developmental characteristics to provide clarified descriptions, including indicative morphological changes that occur during metamorphosis.ConclusionOur results show that the localized cell division of the proximal part of the endoskeletal disc—the primordium of the proximal radials—and subsequent cell division along the proximal-distal axis, which is restricted to the distal part of the disc during the larva-to-juvenile transition (metamorphosis), lead to the elongation of the proximal radials.Electronic supplementary materialThe online version of this article (10.1186/s40851-018-0105-z) contains supplementary material, which is available to authorized users.

Land Invasion by the Mudskipper, Periophthalmodon septemradiatus, in Fresh and Saline Waters of the Mekong River

“…However, the gills invariably diminish and atrophy with increasing dependence on aerial respiration both in extant fishes 40 and in Devonian transitional animals 1 . It seems therefore possible that the difference in calcium concentration in ambient water affects skeletal modification during the mudskipper’s metamorphosis from larvae (pelagic) to juveniles (amphibious) 41 . Our preliminary examination demonstrated a number of subtle, but significant, differences in body morphologies between sites (Supplementary Tables S3 and S4), indicating a need for further detailed study on the skeletal anatomy.…”

Direct development of the catfish pectoral fin: An alternative pectoral fin pattern of teleosts

“…The anterior margin of the scapulocoracoid contacts the developing intramembranous ossification-that is, the cleithrum bone. 2,4,5,11,18,46,47 The larval muscles are present as two main masses (adductor and abductor) separated by the endoskeletal disk. 12,28 The larval fin innervation is associated with the later muscle differentiation and consists of the first four anterior nerves entering the dorsal and ventral regions of the fin and forming the diffuse network in the muscles and fin membrane.…”

“…2,9,10,12,13 Participation in respiration is regarded as the primary function of the larval fin, 14,15 whereas the adult fin carries other functional loads: locomotion, sensitivity, defense, etc. [16][17][18][19] The fin's larval-adult transition is a part of complex metamorphic transformation that affects various organs and tissues and proceeds under the thyroid hormones' control. 18,[20][21][22][23][24][25] However, the remarkable morphological and functional diversity of teleosts' pectoral fin allows suggesting the hidden developmental potential and existence of lineage specific developmental patterns.…”

“…[16][17][18][19] The fin's larval-adult transition is a part of complex metamorphic transformation that affects various organs and tissues and proceeds under the thyroid hormones' control. 18,[20][21][22][23][24][25] However, the remarkable morphological and functional diversity of teleosts' pectoral fin allows suggesting the hidden developmental potential and existence of lineage specific developmental patterns. 26 Here, we present a thorough description of the development of the pectoral fin skeleton and soft tissues in the North African (African sharptooth) catfish, which displays an alternative fin pattern characterized by a lack of the larval stage typical of other teleosts.…”

No Correlation between Endo- and Exoskeletal Regenerative Capacities in Teleost Species

“…As zebrafish have only a small pectoral endoskeleton, we decided to extend our studies to another teleost species. We chose a mudskipper (Periophthalmus barbarous), as representatives of this family have equally well developed pectoral endo-and exoskeletons ( Figure 1) [33]. Our results from both species suggest that the regenerative capacities of the Teleost endoskeleton are negligible compared with that of the exoskeleton.…”