Natural History of Sharks, Skates, and Rays Locomotion MARE 394 Dr. Turner Summer 2008

Body Form & Propulsion Body form: Distinctive heterocercal tail External morphological symmetry Ventrolateral winglike pectoral fins extending laterally from the body Distinct from actinopterygian (bony) fishes

Body Form & Propulsion Teleost body forms and propulsion mechanisms Anguilliform Carangiform Subcarangiform Ostraciform

Propulsion Mechanisms A&B – Rover Predator C – Lie-in-wait Predator D – Surface Oriented Fish E – Bottom Oriented Fish F – Bottom Clinger G – Flatfish H – Rattail I – Deep-bodied Fish J – Eel-like Fish

Body Form & Propulsion Chondrichthyan body forms and propulsion mechanisms

Body Forms and Fin Shapes Great degree of variability in paired & unpaired fins of sharks – 4 body forms Body Type 1: conical head, large deep body, large pectoral fins, narrow caudal peduncle with lateral keels

Body Form 1 Conical head Large deep body Large pectoral fins Narrow caudal peduncle with lateral keels High aspect ratio tail (high heterocercal); externally symmetrical Thunniform propulsion Fast swimming sharks; reduced pelvic, 2 nd dorsal, and anal fins

Body Form 1 External symmetrical tail aligns mouth with center of mass & thrust to increase feeding efficiency

Body Form 2 Flattened ventral head Less deep body Large pectoral fins Lower heterocercal Lacks keels Subcarangiform propulsion

Body Form 2 Greatest range of swimming speeds Moderately sized pelvic, 2nd dorsal, and anal fins – highly maneuverable

Body Form 3 Large head Blunt snout Anterior pelvic fins More posterior 1 st dorsal fin Low heterocercal; small to absent hypochordal lobe, large subterminal,lobe Subcarangiform propulsion

Body Form 3 Slow swimming speeds; epibenthic, benthic, & demersal

Body Form 4 Wide variety of body shapes United by few characterisitics Lack anal fin Large epichordal lobe Anguilliform propulsion Typically deep to deep-sea

Body Form 4 Typically deep to deep-sea

Body Form 5 Body dorso-ventrally flattened Enlarged pectoral fins Reduction in caudal ½ of body Typically benthic; some pelagic Most batoids, angelsharks, mylobatiforms & Rajiforms

Body Form 5 Most batoids, angelsharks, mylobatiforms & Rajiforms Undulatory Oscillatory

Body Form 6 Laterally compressed Undulate pectoral fins; not axial body Tail long and tapering (leptocercal) to heterocercal

Locomotion in Sharks Orientation of the body one of most important factors 1° means of force Induced swimming with body horizontal (x) and no vertical (y) motion produces positive body angles (lift) Angle of attack decreases as speed increases toward 2l/s

How Locomotion is Measured High speed imagery recorded of shark along with reflective particles in wake

Locomotion in Sharks dd

Locomotion in Sharks Motion of the tail is a key aspect to locomotion – complex 3d manner Kinematics indicates the shark caudal provides thrust and lift by moving water posteriorly and ventrally

Locomotion in Sharks 2 distinct types of pectoral fins in sharks Aplesodic – cardilagenous radials are blunt and extend up to 50% into the fin with the distal web supported only by ceratotrichia* Plesodic – have radials that extend more than 50% into the fin to stiffen it and supplement the support of the ceratotrichia *unsegmented, filamentous fin rays

Locomotion in Sharks Aplesodic fins are more maneuverable; may be used for “walking” on substrate

Locomotion in Sharks Heterocercal tail angle causes a change in body angle

Locomotion in Sharks Which causes lift in a swimming shark Degree of lift is dependent upon the type of tail

Locomotion in Sharks Body orientation, tail thrust, and maneuvering the pectoral fins all coordinate in force balance during swimming

Locomotion in Skates & Rays Batoids either undulate or oscillate the pectoral fins

Locomotion in Skates & Rays Basal batoids (guitarfishes, sawfishes, & electric rays)– undulate thick tails like sharks

Locomotion in Skates & Rays Rays use strict pectoral fin locomotion Undulation – stingrays Oscillation – cownose & manta Movie

Locomotion in Holocephalans Chimeras have long flexible pectoral fins; both undulatory & oscillatory