Feeding Strategies in Teleost FishesBIOE 127

Summer 2015

Vikram B. BaligaEcology & 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 birth22 bones as an adult

Very little kinesis

# of bones varies widely among speciesTypically 30 to 60 bones

Highly kinetic

suction

ram

manipulation(biting)

Aquatic prey capture

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

PolypterusHow Conserved?

Morphological Diversity

Seahorses

Mastacembalus

Anguilla

Catfishes

Cichlids

1) Inertial suction

2) Ram Feeding

3) Manipulation

Three Major Feeding Categories in the Aquatic Environment

NotMutuallyExclusive

Feeding Mechanisms

Suction

Body Ram

JawRam

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

Suction

Body Ram

JawRam

Pure Ram

Pure Ram Strategy

Feeding Mechanisms

Suction

Body Ram

JawRam

Pure Ram

Biting

Extending the Strike

Ram Biters

Biting Diversity

Model Jaw Closing

3rd order lever

Speed Force

0 1

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

Cundall &Greene, 2000

Mehta & Burghardt, 2008; Mehta 2009

Snakes

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

kPa = -1• Micropterus salmoides

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

Suction

Body Ram

JawRam

Pure Ram

Biting