Feeding Strategies in Teleost Fishes BIOE 127 Summer 2015
Vikram B. Baliga Ecology & Evolutionary Biology UC Santa Cruz
Environment
Characteristic Air Water Density 1.21 kg m-3 1.024 x 103 kg m-3 Dynamic Viscosity 18.08 x 10 -6 Pa*s 1.07 x 10 -3 Pa*s
O2-Carrying Capacity 95% less than air Thermal Conductivity 23 x air Human Skull Fish Skull
44 bony elements at birth # of bones varies widely among species 22 bones as an adult Typically 30 to 60 bones Very little kinesis Highly kinetic Aquatic prey capture
suction
ram
manipulation (biting)
Liem, 1980 Steven Day Tim Higham
Roi Holzmann Kristen Bishop Lepomis macrochirus
DPIV Experiments DPIV: Flow Velocity Hydrodynamics of Suction Feeding (Day et al. 2005)
I. Flow = symmetrical
II. Velocity decreases drastically away from the mouth
III. Fluid speed is only significant within 1 mouth diameter How Polypterus Conserved?
Morphological Diversity
Seahorses Mastacembalus Anguilla Catfishes Cichlids Three Major Feeding Categories in the Aquatic Environment
1) Inertial suction
Not 2) Ram Feeding Mutually Exclusive
3) Manipulation Feeding Mechanisms
Body Ram
Suction
Jaw Ram Jaw Ram Necessitates Jaw Protrusion Jaw Protrusion Extremes Why might jaw protrusion have evolved? 1. Sneak up on your prey
2. Increase forces exerted on your prey Research on Jaw Protrusion
• Accelerates the water around the prey
• Increase by up to 35% the total force exerted on attached, escaping and free-floating passive prey
• the strike. Feeding Mechanisms
Body Pure Ram Ram
Suction
Jaw Ram Pure Ram Strategy Feeding Mechanisms
Body Pure Ram Ram
Suction
Jaw Ram Biting Extending the Strike Ram Biters Biting Diversity Model Jaw Closing
3rd order lever
0 1
Speed Force MA jaw –closing
Needlefish 0.04 (Strongylura incisa)
Gar 0.051 (Lepisosteus osseus) Barracuda 0.27 (Sphyraena barracuda) Queen trigger 0.43 (Balistes vetula) Summary Functional Roles of Suction
1. Respiration
2. Prey Capture
3. Prey Transport Gill Filaments 4,5 Prey Transport
Mouth -> -> -> Branchial Arches -> oesophagus Sciaenops ocellatus -Red Drum
Grubich and Westneat. 2006. Journal of Anatomy 1: 79-92 Pharyngeal Musculature Pharyngeal Jaw Epibranchial
Pharyngobranchial
ceratobranchial Pharyngeal Diversity
(a) Papilliform –plant shredding (b) Molariform- crushing snails Snakes
Mehta & Burghardt, 2008; Mehta 2009
Cundall &Greene, 2000 Elongate Limb-reduced Forms Teleost Phylogeny Anguilliforms Morays
• ~ 200 species • Complete limb loss • Coral reefs
Snakes Morays
• Elongate & limbless • Can attain large sizes • Obligate predators/ Consume large prey whole • Affect local prey densities How do morays consume large prey whole in the aquatic environment?
Moray Skull
What consequences do these features have on feeding behavior? Can morays generate suction? Pressure Data
• Muraena retifera • Micropterus salmoides kPa = -1 kPa = -8
Mehta, unpubl data. Biters use suction to transport prey Inertial Feeding
Pharyngeal Jaws
Halichoeres bivittatus Morphological & Functional Innovation Prey Transport Behavior Thank you
UCLA HARVARD LABORATORIES Feeding Mechanisms
Body Pure Ram Ram
Suction
Jaw Ram Biting