Dasyomyliobatis thomyorkei is intermediate between the ‘rajobenthic’ and more derived ‘aquilopelagic’ stingrays, supporting the hypothesis that the aquilopelagic body plan arose in association with the evolution of durophagy (specializations for crushing or cracking hard prey) and pelagic lifestyle from a benthic, soft-prey feeder ancestor.
“Rays (Batoidea) are a diverse group of cartilaginous fishes whose body plan is adapted for a benthic lifestyle,” said University of Turin’s Professor Giorgio Carnevale and his colleagues.
“While guitarfishes and electric rays use their tail for locomotion, skates and stingrays (Myliobatiformes) use their pectoral fins for both locomotion and feeding.”
“Stingrays show the highest morphological disparity; most species possess a rounded to rhombic, soft and flexible pectoral disc supported by radials with four-chain catenated calcification that allow undulatory swimming in which multiple waves propagate along the pectoral-fin margin.”
“These features, coupled with a mostly negative fin-ray distribution index and low pectoral-fin aspect ratio, are particularly efficient for swimming at low speed above the bottom.”
“These stingrays also use their pectoral disc to constrain and press prey against the substrate (tenting behavior). Prey are then grasped and processed through batteries of numerous, small, holaulacorhizous teeth of orthodont or osteodont histotype, forming the so called crushing-type dentition.”
“This feeding apparatus is not designed for durophagy but allows benthic stingrays to grasp, suck and chew, giving them the ability to consume a large variety of soft prey mainly including bony fishes, annelids and thin-shelled crustaceans.”
“This body plan represents the generalized ‘rajobenthic’ ecomorphotype, making benthic soft-prey feeder stingrays among the most successful colonizers of shallow-water habitats in freshwater and marine environments.”
“Another group of…
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