Comparative analysis of the morphology of the feeding apparatus in myliobatiform rays (Chondrichthyes: Batoidea)

• Grant number: 12/22366-4
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date: February 05, 2013
• End date: April 04, 2013
• Field of knowledge: Biological Sciences - Zoology - Taxonomy of Recent Groups
• Principal Investigator: Marcelo Rodrigues de Carvalho
• Grantee: Akemi Shibuya
• Supervisor: Luiz A. Rocha
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: California Academy of Sciences, United States
• Associated to the scholarship: 11/23683-0 - A comparative morphological study of the feeding mechanism in rays of the order Myliobatiformes (Chondrichthyes: Batoidea), BP.PD

Abstract

The euhyostilic jaw suspension of batoids is effected only by the hyomandibular cartilages supporting the mandibular elements, without any articulation or connection between the neurocranium and palatoquadrate. However, morphological differences in the feeding apparatus and orobranchial musculature can lead to different prey capture and manipulation modes in batoids. Inaddition, some species are capable of feeding on hard prey, such as mollusks and crustaceans, which may be related to trabeculation of the palatoquadrate and Meckelian cartilages that absorb the stress generated by crushing prey of this type. Thus, in order to understand the evolution and function of thejaw suspension in myliobatiforms, the arrangement and morphology of the jaw suspension and associated orobranchial musculature will be extensively analyzed in species of this order. The morphology of the feeding apparatus will be related to existing information on the diet and feeding habits of the analyzed species. Specimens will be obtained from museums and collections for dissection. The orobranchial musculature will be removed and its performance during prey capture and manipulation will be analyzed using the value of relative dry mass of each muscle set involved in the feeding process. The morphology of jaw suspension will be described and the palatoquadrate and Meckelian cartilages will be analyzed histologically to reveal trabeculation. To comprehend theevolutionary significance of the different feeding patterns, the results will be incorporated into available phylogenetic hypotheses for myliobatiform rays. The relationship between a specific feeding apparatus and its functionality, in relation to the consumption of different prey types, may provide information concerning the peculiar feeding mechanics of myliobatiform species, and may also contribute to clarify the evolution of this order. (AU)