LSM3261_Lecture 13 --- Sensory Perception and Feeding

LSM3261 Life Form and Function

Sensory reception, feeding and other

features

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• 08 - Animal diversity and basic designs

• Lecture 09

• Animal symmetry;

• Organisation of the animal body;

• Transmission of messages/materials within the animal body

• Animal form and function in relation to:

• 10 - Protection

• 11 - Support & Locomotion

• 12 - Locomotion (Flight)

• 13 - Sensing the environment, Feeding

LSM 3261 Life Form Structure & Function

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Life Form and Function

Part I - Sensing the EnvironmentLSM3261 Zoology Lecture 6

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Objectives

• To think about:

• Sensing the environment

• Procuring food in animals

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• Importance

• detect changes in the environment (internal and external environment, position)

• respond to those changes in good time

Sensory reception

• How?

• Sensory receptors are free endings of neurons and/or specialised cells/tissue/organs which detect stimuli

• Information processed by nervous system to electrical energy

• Receptor potential generated which can initiate action potentials (nerve impulse)

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1. Mechanoreceptors

2. Chemoreceptors

3. Thermoreceptors

4. Electroreceptors

5. Photoreceptors

Types of sensory receptorsbased on the stimuli they receive

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1. Mechanoreceptorsrespond to touch, pressure, gravity, stretch or movement

Sensing

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• Touch receptors (invertebrates and vertebrates – tactile).

• Located in skin.

• Often associated with tactile hairs.

• Free nerve endings.

• Encapsulated nerve endings.

Mechanoreceptors - Detecting vibrations and movement

! Stimulated by mechanically-induced distortion! Associated with touch (pressure/pain), hearing, balance

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1.1 Types of mechanoreceptors

• 1.1a Proprioreceptors

• Inner ear

• Lateral line

• 1.1b Otoliths

• 1.1c Statocysts

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Mechanoreceptors

• 1.1a Proprioceptors (“inner sense,” “sense of self”)

coordinate muscle movement in vertebrates

• Stimulated by movement/tension in contracting

muscles, tendons, and ligaments

• Multisensory input contributes to ‘simple tasks’,

e.g. try standing on one foot

• Kinesthetic awareness = sense of body in space and time,

e.g. how your finger finds your nose

• E.g. ‘natural athletes’ versus clumsiness;

train to overcome

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Inner ear, humans- ends in hair cells

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• Inner ear – cochlea (tetrapods – auditory receptors)

• Three fluid filled canals. Middle (cochlear duct) with hair cells and endolymph

Sound waves

! tympanic membrane (ear drum)

! amplification: middle ear bones (malleus, incus, stapes)

! oval window

! stimulation of hair cells in cochlear duct

position, acceleration, and gravity changes

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• Inner ear – vestibular apparatus (vertebrates – sensing position and orientation of body)

• Saccule and utricle – chambers with hair cells and otoliths; different planes

• Semicircular canals – three canals at right angles, with hair cells and endolymph

Utricle

Saccule

Vestibular apparatus

Semicicular canals

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Dept Otarology, Washing School of Medicinehttp://oto2.wustl.edu/thc/otoconia.htm

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Balance disorder

• “A balance disorder is a disturbance that causes an individual to feel unsteady, giddy, woozy, or have a sensation of movement, spinning, or floating.”

• “Infections (viral or bacterial), head injury, disorders of blood circulation affecting the inner ear or brain, certain medications, and aging may change our balance system and result in a balance problem.”

http://www.nidcd.nih.gov/health/balance/balance_disorders.asp

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Lateral line system of fish

- ends in hair cells

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Skin

Lateral line

Lateral line nerve

Opening of lateralline canal

• Lateral line organ (aquatic vertebrates) – touch,

pressure, gravity, movement

" Hair cells - stimulated by vibrations in water

" Water transmits vibrations better air

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Tetra evading Kingfisher

Thanks to Xu Weiting(LSM3261-2008)

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Mechanoreceptors• 1.1b Otoliths (bony fish have three pairs)

• Small particles suspended in the viscous fluid of the saccule and utricle (ear).

• Inertia of otoliths during movement stimulates hair cells

• Tiny calcium stones in vertebrate ear are called otoconia

• Do you expect all these fish to have similar sized otoliths?

• Coral reef, rocky bottom

• Open ocean

• Flying fish

• How would ecologists find otoliths useful?

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Paxton, 2000. Fish otoliths: do sizes correlate with taxonomic group, habitat and/or luminescence? Phil. Trans. R. Soc. Lond. B.

Suggests

• Eel have small to very small otoliths - more important sense of smell than hearing.

• Bathypelagic nocturnal fish have large eyes as well as large otoliths - senses of both sight and hearing are heightened.

• Luminous species have slightly to much larger otoliths than non-luminous species in the same family. Need to hear better?

• Most epipelagic (surface) fish have very small otoliths, perhaps due to background noise and/or excessive movement of heavy otoliths in rough seas.

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A pair of sagittae from a Pacific Cod, (Gadus macrocephalus).

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ICE AGE PALEONTOLOGY OF SOUTHEAST ALASKAhttp://orgs.usd.edu/esci/alaska/fish.html

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Mechanoreceptors

• 1.1c Statocysts (invertebrates – gravity)

• Invagination of sensory epidermis with sensory hair cells (setae) and statoliths

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1.2 Seeing by sound:Echolocation in bats

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Take insects by the wing in total darkness

Seeing by sound: Echolocation in bats

Insectivorous bats produce ultrasonic squeaks (20kHz) and

pick up reflected echo.

Emit from mouth/nose - very loud.

Very precise – can catch 2 flying mosquitoes in half a second

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Aerial hunting bats capture prey either with the wing or the tail membrane. Acoustic tasks: target detection, localization, and tracking.

1. Emit short ultrasonic signals.2. Listen for the echoes reflected from

surroundings and prey. 3. Pursuit: signal duration decreases,

repetition rate increases:

• Search,

• Approach and

• Terminal buzz phase.

Hunting insects on the wing(Microchiropterans)

http://neurophilosophy.files.wordpress.com

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Moss, C. F. & S. R. Sinhay , 2003. Neurobiology of echolocation in bats. Current Opinion in Neurobiology, 13:751–758.

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Moss, C. F., K. Bohn, H. Gilkenson & A. Surlykke, 2006. Active listening for spatial orientation in a complex auditory scene. PLoS Biol., 4(4): e79 doi:10.1371/journal.pbio.0040079

Eptesicus fuscus capture of tethered insectsclose to background vegetation

(i.e. Distance of insect to vegetation)

FM signalling, suited for

open habitats

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1. Prey cannot hear predator - sitting duck?

2. Some moths can hear bat sonar, avoid bat.

3. Some bats whisper, go into “stealth mode”.

4. Some moths can emit sounds to jam bats.

5. Bats can shifting pitch to avoid jamming.

A good read - “Electronic Combat in Nature,” by Aaron Chia Eng Seng. DSTA Horizons 2006. http://www.dsta.gov.sg/index.php/DSTA-2006-Chapter-4/

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Brown Bat (Eptesicus fuscus)feeds on silenced Tiger Moth

Corcoran & Connor, 2009

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Bat sonar is jammed by Tiger Moth acoustics

Number of successful hunt increased by 75%when moth tymbal damaged

25% brown bats ignored moth prey- reasons unknown

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Sequencing fecal DNA revealed that barbastelle bats eat almost exclusively eared moths

Barbastelle calls are 10–100! lower in amplitude than those of other aerial-hawking bats

Bats with these “stealth” calls hear moth echoes before moths are likely to react

Stealth echolocation gives bats an advantage in the arms race with eared moths

An Aerial-Hawking Bat Uses Stealth Echolocation to Counter Moth Hearing.

Holger R. Goerlitz, Hannah M. ter Hofstede, Matt R.K. Zeale, Gareth Jones, and Marc W. Holderied. Current Biology, August 19, 2010 DOI: 10.1016/j.cub.2010.07.046

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• “The homing behaviour of Eptesicus fuscus (Big brown bat),

• can be altered by artificially shifting the Earth’s magnetic field,

• indicating that these bats rely on a magnetic compass to return to their home roost.”

Holland et al., 2006. Bat orientation using Earth’s magnetic field. Nature, 444: 702 - 702.

Not just echolocation

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After 45 min exposure to a rotated magnetic field

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1.3 Echolocation in toothed whales

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! 1. Mechanism

! 2. Diversity

! 3. Sperm whales used to predate on nautiloids

! 4. Echolocation in whales and bats an example of convergent evolution

Echolocation in toothed whales

(C)Photo TAI Chestnut Hill

http://southwest.com.au/~kirbyhs/dolphins4.html

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• Sperm whales, beaked whales, dolphins

• single blowhole dorso-anteriorly (one nostril dominant; baleen whales have two)

• asymmetric skulls

• melon on heads focus’ sound waves

• no vocal cords (blowhole system produces sound)

• no sense of smell or saliva glands.

Toothed whales

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Whales, dolphins, also use ultrasonic echolocation

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Whales, dolphins, also use ultrasonic echolocation

Prominent fatty melon on head of toothed whales involved in focusing ultrasonic clicks into a beam

Returning echoes reach inner ear via fat-filled lower jaw

Many use ultrasonic sound to stun fish

) ) ) ) ) ) ) ) ) ) ) )

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! All toothed whales (Odontocetes) echolocate

! Dive beyond reach of sunlight

! 200m - dolphins

! >1,000m - belugas, narwhals

! 3,000m - sperm whales

! The first whales entered water 45MYA

! No scooped forehead - did not echolocate

! Such skulls arose 32MYA" Echolocation allowed whales to find

food!

Echolocation in toothed whales

(C)Photo TAI Chestnut Hill

http://southwest.com.au/~kirbyhs/dolphins4.html

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Do sperm whales

eat giant squid?

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Do sperm whales eat giant squids?

• “Researchers estimate that more than 110 million tons (100 million metric tons) of squid

• —equivalent to the entire annual harvest of all the commercial fisheries on Earth

• —may be consumed by sperm whales every year.”

“Jumbo squid, sperm whale study reveals how the giant creatures feed, hunt,” by Stefan Lovgren.

National Geographic News, 12 Mar 2007.

Davis et al., 2007. Diving behavior of sperm whales in relation to behavior of a major prey species, the jumbo squid, in the Gulf of California, Mexico. MEPS, 333: 291-302.

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• During the day the whales and squid spent about 75 percent of their time at 180 - 400 m.

• At night, tagged squid spent at least half of their time above 180 meters, most likely following small vertically migrating prey rising form the depths.

• Diving pattern of tagged sperm whales only slightly altered at night; mostly remained at lower depths.

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• The whales are not foraging where the squid are the most abundant.

• Squid make rapid nighttime dives to deeper waters for recovery (not optimised for surface feeding) and are relatively inactive.

• During their deep night time foraging, recovering squid may be more susceptible to predation by sperm whales.

• At low-oxygen levels, the reaction times of squid may also be slower, making them easier to catch!

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NautiloidProfberger, http://

en.wikipedia.org/wiki/Image:Nautilus_profile.jpg

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Nautiloids

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• The first whales entered the ocean from land about 45 million years ago.

• They did not echolocate — fossil skeletons do not have the scooped forehead of today's echolocating whales.

Epipelagic predation of nautiloids by whales (2007)

http://berkeley.edu/news/media/releases/2007/09/05_WhaleSonar.shtml

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• When whales developed biosonar, nautiloids dominated the oceans.

• Whales were able to track hard-shelled nautiloids by bouncing sounds off their hard shells.

• An advantage over other whales dependent only on moon or starlight.

• And they could follow nautiloids into the depths (mesopelagic predation) when they migrated!

Epipelagic predation of nautiloids by whales

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• Cephalopod prey migrated up and down on a daily "diel" cycle for at least 150 million years.

• Even today, squid densities highest about a depth of 500 - 1,000 meters (day).

• At night, nearly half are within a 150 meters depth.

• Squid fishing is done at night!

Geomr, http://commons.wikimedia.org/wiki/Image:Hakodate_squid_fishing_2005-08.JPG

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http://berkeley.edu/news/media/releases/2007/09/05_WhaleSonar.shtml

Cephalopods have migrated up and down on a daily "diel" cycle for at least 150 million years

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• Over the millennia, shelled cephalopod species in particular fell as the number of whale species boomed. Predation?

• 10 MYA nautiloids driven out of open ocean into protected reefs.

• Whales forced to improve their sonar to hunt soft-bodied, migrating squid (including the giant squid) - requires more sophisticated sonar.

Whales ran out of nautiloids?!

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• Bats, developed a sensory system for seeing with sound.

! Whales did so too.

• Different bat species echolocate in different ways.

! Every single toothed whale species echolocates in a different way.

Convergent evolution in echolocation strategies:

whales and bats

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• Bat sonars has different phases during searching/hunting and acquisition of prey, including a terminal buzz.

! Whales exhibit the same. (regular series of "clicks" becomes "buzzes"

• Bats partition the tree canopy and preferentially hunt insects at specific heights.

! Whales partition the water column, specializing in harvesting squid at specific depths.

Convergent evolution in echolocation strategies: whales and bats

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Convergent evolution in echolocation strategies:

whales and bats

• Bats took advantage of unexploited food resources: nocturnal insects.

! Whales did likewise with cephalopods.

• Fruit bats that depend on dense seasonal resources do not echolocate.

! Likewise filter-feeding baleen whales lack biosonar.

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Some of the sources

• Lindberg, D.R. & N. D. Pyenson, 2007. Things that go bump in the night: evolutionary interactions between cephalopods and cetaceans in the tertiary. Lethaia, 40(4): 335-343/December 2007. 10.1111/j.1502-3931.2007.00032.x

• Review of this article - “Migrating squid drove evolution of sonar in whales and dolphins, researchers argue.” Science Daily, 06 Sep 2007. http://www.sciencedaily.com/releases/2007/09/070905143411.htm

• Watwood et al., 2006. Deep-diving foraging behaviour of sperm whales (Physeter macrocephalus). J. Animal Ecology, 75 (3), 814–825. doi:10.1111/j.1365-2656.2006.01101.x

• Review of this article -“Ecologists home in on how sperm whales find their prey.” Science Daily, 29 May 2006. http://www.sciencedaily.com/releases/2006/05/060529103339.htm

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1.4 Echolocationin humans

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! Human echolocation is an active mode of perceptionin which acoustic information contained in [echoes of] sounds returning from surrounding obstacles is processed to derive spatial information.

! Most visually handicapped people spontaneously and intuitively generate sounds when they move around in order to gather spatial information.

" e.g. tongue clicks, snaps, hissings or vocalizations [tapping of cane]

Human Echolocation

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! Congenitally blind children learn to attach spatial meaning to sound patterns to which they are exposed without specific training.

! Diderot’s "Letter on the Blind" (1749) describes a blind man who could render a squirrel unconscious by throwing an object accurate enough to hit the squirrel’s forehead.

! “Facial vision” until the 40’s.

Human Echolocation

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Ben Underwood

• Lost eyes to cancer, aged 2

• Mother learns of his ability to perceive surroundings, aged 5; now aged 16

• Echolocates

• 2006 - People magazine, CBS news, “Extraordinary People” tv series, Youtube, Oprah, etc.

slate.com

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Ben Underwood

• Exceptional, but not studied yet.

• Age factor?

• We can echolocate too.

• Not all blind people can hear well.

slate.com

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• [Innate ability] Ashmead, D.H., E. W. Hill & C. R. Talor, 1989. Obstacle perception by congenitally blind children. Perception and Psychophysics, 46[5]: 425-433.

• [Review of early literature] Kells, K., 2001. Ability of blind people to detect obstacles in unfamiliar environments. J. Nursing Scholarship, 33 (2): 153-157.

• [Review of subject] Wiener, W. R. & G. D. Lawson, 1997. Audition for the traveler who is visually impaired. In: B. B. Blasch, W. R. Wiener, R. L. Welsh (eds.), Foundations of Orientation and Mobility. 2nd edition. American Foundation for the Blind. Pp. 104-169.

Some references, for the curious

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2. ChemoreceptorsTaste and smell – detecting chemical substances in food, water and air

Sensing

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2. Chemoreceptors - Detecting chemicalsTaste and smell – detect chemical substances in food, water and air

Snakes actually taste air Catfish barbels covered with taste buds

Pheromones – small, volatile molecules, used to communicate (e.g., attracting mates, marking territory)

Antennae of male moth (Bombyx mori) capable of detecting 1 molecule of the female sex pheromone per 1015 air molecules

Male Indian luna moth (Actias selene) has most well developed chemical detection. Can trace female 11km away

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olfactory bulb

Young, 1981

Vomeronasal Organ (Jacobson’s organ)

- inside mouth- invaginations in palate

- lined with nerve endings- connected to olfactory bulb

- lacrhymal duct provides moisture

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http://maxshouse.com/vomeronasal-flehmem.htm

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http://en.wikipedia.org/wiki/Image:Sumatratiger-004.jpg

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“Mouth gaping by rattlesnakes has been observed primarily during feeding sequences and interpreted as functioning to

stretch the jaw in preparation for swallowing prey.

However, exposure of prairie rattlesnakes to conspecific sociochemical signals elicited increased mouth-gaping

actions, and the latter were sequentially followed by tongue flicks at significant levels.

Mouth gaping may function to facilitate vomeronasal olfaction independent of jaw-stretching effects.”

- Graves, BM & D. Duvall, 2005.Occurrence and function of prairie rattlesnake mouth gaping in a non-feeding

context. J. Experimental Zoology, 227(3): 471 – 474.

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• The world's largest hornet, Vespa mandarinia japonica (Japanese hornet, 27 to 55 mm length).

• Volatile alarm pheromone identifies nest invaders and marks prey (e.g. honeybees).

• Pheromone spurs an attack by a large group of nest-mates.

Japanese hornet alarm pheromone

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• en masse predation of other social bees and wasps

• A lone foraging hornet rubs around a prey food resource (e.g. honeybee colony),

• Hornet nest-mates congregate and attack marked site en masse!

• Only demonstrated by V. m. japonica

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Japanese hornet alarm pheromone (1995)

• 300 Japanese hornets can destroy

• a nest of 30,000 European honey bees

• in 3 hours

• Hornets are 5 times larger, armoured

• These two species did not co-evolve.

• European honey bees were only recently imported to Japan, i.e. non-native.

• Too recent to have evolved a defense.

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• The Japanese honeybee (Apis cerana japonica) can detect the hornet marking pheronome,

• responds by increasing the number of defenders at the nest entrance.

• The invading hornet is captured.

• > 500 other bees quickly engulf the hornet in a ball which contains isoamyl acetate (”smell of bananas” - chemical used in artificial flavouring, e.g. bubblegum)

• Ball temperature is very high (~47 °C) -lethal to hornet not the bees.

• Co-evolution; this unique defense not seen in the European honey bee.

Co-evolved defense of native honeybee

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3. ThermoreceptorsDetecting heat

Sensing

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3. Thermoreceptors - Heat detection

Pit organ

Two groups of snakes: Boidae, Crotalidae

Heat-sensitive pits contain membranes with numerous nerve endings

Sensitive to changes in infrared radiation or temperature

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• Invertebrates that feed on blood – detect endothermic prey using thermoreceptors

E.g. mosquitoes, ticks, leeches

• Mammals – thermoreceptors in skin and tongue

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The (immune) California ground squirrel (Spermophilus beecheyi) deters northern Pacific rattlesnakes by heating up its tail and

waving it over the heat-sensitive reptile.

Encounter with rattlesnake,

Crotalus oreganus

Encounter with non-heat sensitive

gopher snake, Pituophis

melanoleucus

An increase in tail temperature effectively deterred the snakes from approaching.

Rundus, Owing, et. al., 2007

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4. ElectroreceptorsDetecting electrical fields

Sensing

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4. Electroreceptors - detecting electrical fields (fishes)

• Navigation

• Orientation

• Communication

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http://en.wikibooks.org/wiki/Image:Electroreceptors_in_a_sharks_head.svg

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Electric ray aka Numbfish (Narcine sp.)83

5. PhotoreceptorsDetecting light

Sensing

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5. Photoreceptors - Seeing by light

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Many origins, opsins common

eye spot in Euglena

pinhole in Nautilus

cup eye spot in Planarians

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Most invertebrates:

• Eyespots (ocelli)

• Groups of light-sensitive cells for detecting direction and intensity of light

• Do not form images

• Compound eyes (many facets)

• Highly sensitive to movement

• Sensitive to UV light

• Composite or mosaic image (images poorly formed)

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Vertebrates and cephalopod eyes:

• Camera-like:

• Adjustable lens (accommodation – changing focus between near and far objects)

• Adjustable diaphragm (iris)

• Light sensitive-layer (retina)

• Images sharp

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Suspensory ligaments taut

Ciliary musclesrelax, and lens is

pulled to a flatter shape

Distant vision

ACCOMODATION

Accommodation for close vision requires tension to be exerted to

deform the lens—contraction of ciliary muscles changes the shape of the lens.

Accommodation is the process by which the eye increases optical power to maintain a clear image (focus) on an

object as it draws near the eye. Near visionRetina

Lens stretched

Ciliary muscles contract, lens “rounds up”

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Position of eyes

• Predator - binocular

• Prey - lateral

Also (tested in raptors),

• lateral vision - scan for distant prey in open areas

• wide binocular field - enhance prey detection in closed habitats (O’Rourke et al., 2010)

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Thomas Shahan @ Flickr

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“Jumping spiders, or salticids, sample their environment using a combination of two types of eyes.

‘Principal’ eyes - a forward-facing pair with narrow fields of view, but exceptional spatial resolution

‘Secondary’ eyes - two or three pairs with a wide field of view and function especially well as motion analysers.

Motion detected by the secondary eyes may elicit an orienting response, whereupon the object of interest is examined further using the high-acuity principal eyes.

Females have a higher propensity to orient toward moving objects than males, probably as females experience higher nutritional demands.”

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Aragog

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Hogna Wolf Spider

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Life Form and Function

Part II - FeedingLSM3261 Zoology Lecture 6

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Carnivorous species can

• wait for prey to come within reach• actively hunt prey

Various strategies to increase opportunities or chances of success for food procurement:

1. Immobilising prey

2. Jaws

3. Mouth

4. Teeth

5. Talons, Claws, Chelae

6. Sticky tongue

7. Lures

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1. Immobilising prey

Feeding

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1. Immobilising prey

Species can take more active prey by immobilising them

Coiling round prey or injecting venom (e.g., snakes, cone shells,

spiders, scorpions)

Shock waves (e.g., snapping shrimp, numbfish, dolphins,

whales)

Entangle prey in sticky or mucus threads (e.g., spiders, hagfish,

velvet worm)

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2. Jaws/Mouth

Feeding

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Development of jaws among the vertebrates (from fish) enabled them to take large and active prey, thus increasing

food opportunity- Developed from visceral skeleton

In invertebrates, moving mouth parts such as mandibles help to grip prey

- Developed from appendages or exoskeleton

2. Jaws

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Roles for Dlx transcription factors in patterning along the proximal–distal axis of the pharyngeal arches in agnathan and gnathostome vertebrates.

Homologous pharyngeal arch segments are numbered 1–7; skeletal elements and the Dlx genes they express are color-coded (red=dorsal; blue=intermediate; yellow=ventral). DEPEW ET AL., 1999; 2002.

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Extensible jaws

• Mechanism in fish efficient for sweeping/sucking prey into mouth

• Food sucked into mouth by expansion of buccal cavity and

protrusion of jaws (premaxillae) to form “suction tube”

• Mechanism of tube formation by jaws evolved independently in

different groups of fishes

Example of convergence

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2.2 Pharyngeal jaws

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3. Mouth

Feeding

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The archerfish can shoot a jet of water accurately at a resting insect on a branch above the

water

Tube formation - tongue raised against groove in roof of mouth

Jet of water forced out of mouth by rapid closure of gills

3. Mouth modification in Archer Fish

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Tube formation with ridge on

tongue and groove in roof of mouth.

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• For any given size of prey, the fish hit them with about ten times the force needed to dislodge their adhesive parts from their footholds.

Schlegela, T., C. J. Schmidaand & S. Schustera, 2006. Archerfish shots are evolutionarily matched to prey adhesion. Current Biology, 16 (19):

R836-R837. doi:10.1016/j.cub.2006.08.082

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4. Teeth

Feeding

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4. Teeth

Teeth are useful for preventing prey from struggling out of the

mouth

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Python skull – teeth directed backwards which prevents escape of prey from mouth

Homodont dentition(fishes, amphibians, reptiles)

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3.1.4.3---------3.1.4.3

3 1 4 3I C P M 3 1 4 3

Heterodont dentition in most mammals

• For varied diets (carnivory, herbivory, omnivory)

• Incisors; canines; premolars; molars

• Dental formula:

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Incisors

CaninesPremolars Molars

CARNIVORECanine

Incisors

Premolars Molars

HERBIVORE

Canines

Incisors

Premolars Molars

OMNIVORE

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Order CARNIVORA

• Includes predators/hunters with specialised morphological adaptations (e.g., cats)

• Teeth differentiated: incisors for cutting; enlarged canines for tearing; blade-like premolars and anterior molars for cutting; posterior molars reduced

• Last upper premolar and first lower molar modified into cutting blades - carnassials

• Jaws powerful, articulation firm and rigid

• Toes end in strong claws which are held back by ligaments and extended by muscles only when needed

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Hickman et al, 2011

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temporal

masseter

Massive cheekbones for attachment of jaw

muscles

Muscles attaching lower jaw to upper known as

masseter muscles

Move lower jaw forwards and backwards

cheekbone

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5. Talons, Claws, Chelae

Feeding

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5. Talons, claws

Predatory birds use well-developed talons to seize prey

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Schenk, S. C. & P. C. Wainwright, 2001. Dimorphism and the functional basis of claw strength in six brachyuran crabs. J. Zoology, 255 (1): 105-119.

http://journals.cambridge.org.libproxy1.nus.edu.sg/action/displayAbstract;jsessionid=83F240F586FAF6D7E02EA7F49D235647.tomcat1?fromPage=online&aid=83423

6. Chelae

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6. Sticky tongue

Feeding

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Sticky tongue

Sticky tongue efficient in terrestrial environment (ineffective in the aquatic

environment)

Use of sticky tongue to capture prey evolved independently in various

tetrapod groups

Frogs

(Amphibia: Anura)

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• Chameleons preferred habitat = shrubs and trees

• Foraging mode = sit-and-wait ambush predator

• Chameleons diverge from the primitive prey-capture mode with a highly specialised ballistic tongue projection mechanism - they projecting their tongue ballistically up to twice their body length to capture prey.

• Other morphological and behavioural characters for this niche:

• cryptic coloration,

• slow locomotion and muscle physiology,

• zygodactylous feet and

• a prehensile tail.Schwenk, K. (2000). Feeding in lepidosaurs. In Feeding:

Form, Function and Evolution in Tetrapod Vertebrates (ed. K. Schwenk), pp. 175–292. San Diego: Academic Press.

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Chameleons(Reptilia: Chameleonidae)ballistic tongue projection

Common Chameleon,Chamaeleo chamaeleon

What is this an example of?

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Pough et al., 1990

Woodpeckers (Aves: Piciformes)

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Anteaters have long sticky tongues that are efficient in

sweeping up ants and termites and in probing tight crevices for the

insects

Mammalia: Edentata

Giant anteater Armadillo

Tamandua

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Ant-eating habit has developed independently among unrelated groups of mammals (convergence):

Banded anteater (Marsupialia)

Pangolin (Pholidota)

Aardvark (Tubilidentata)

Spiny anteater (Monotremata)

• Anteaters have in common:

• long snout & long, sticky tongue

• large salivary glands

• reduced teeth

• strong front limbs with long claws

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7. Lures

Feeding

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Use of lureE.g., frog fish

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Use of lure. E.g., alligator snapping turtle

Humpback anglerfish133

Sexual parasitism

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Reading Week Consultation• sivasothi@nus.edu.sg - email me questions

or ask for an appointment

• See me at @ Lab 7 - Fri 18 Nov 2011: 2pm-6pm

• IVLE Chat session for LSM3261: Fri 18 Nov 2011: 9.00pm

• Exam on Wed 23 Nov 2011: 9am - 11am

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