Publication Date

2008-06-23

Availability

Open access

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PHD)

Department

Biology (Arts and Sciences)

Date of Defense

2008-04-04

First Committee Member

Steven Green - Committee Chair

Second Committee Member

Philip Motta - Committee Member

Third Committee Member

Keith Waddington - Committee Member

Fourth Committee Member

Daniel DiResta - Committee Member

Abstract

Foraging presents a significant challenge for neonatal predators. Both physical maturation and predatory experience may improve predatory abilities. To tease apart which improvements in predatory abilities were due to increased maturation and which to increased experience, several experiments that isolated the effects of maturation and experience were conducted. Individual whitespotted bamboosharks, Chiloscyllium plagiosum, improved predatory efficiency with both maturation and experience. Physical maturation, when isolated from experience, improved predatory efficiency of naïve sharks foraging on shrimp, an elusive prey, but not of sharks foraging on worms, a non-elusive prey. Predatory experience, when isolated from maturation, improved predatory efficiency of sharks foraging on worms but not of sharks foraging on shrimp. Both maturation and experience are important in the development of whitespotted bamboosharks' predatory abilities and may influence the type of prey they can exploit. To determine whether whitespotted bamboosharksare able to retain the ability to capture and eat prey after a period of prey absence, sharks that had 20 days of foraging experience were denied access to live prey for 18 days, after which they were re-exposed to live prey. Predatory efficiency of sharks did not decrease during the 18 day prey-absence period. After sharks were re-exposed to live prey, their predatory efficiency was similar to that of sharks of the same age with equivalent experience but no prey-absence period, but was higher than that of naïve sharks. Whitespotted bamboosharks retain the ability to catch and consume prey after a short period of prey absence. This retention may improve their ability to forage on prey that is spatially or temporally patchy. To determine whether experience with one prey type affects the whitespotted bambooshark's ability to forage on novel prey, sharks that had 20 days of experience foraging on one type of prey (either worms or shrimp) were given foraging trials with the other prey. Experience with one prey improved sharks abilities to forage on novel; sharks foraging on novel prey were as efficient as sharks that had foraged on that prey for 20 days. Whitespotted bamboosharks can maintain or easily modify many predatory skills when foraging on novel prey.

Keywords

Predatory Behavior; Learning; Shark; Fish; Growth

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