W41. Examples of Oriented Behavior. Collective behavior of bacteria around a food source. Sensory Guidance and Oriented Behavior

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1 Sensory Guidance and Oriented Behavior Lecture 40 BioNB4240 W41 1) Spend 4 hours normally devoted to writing assignment on your Wikipedia project 2) Put your notes and outlines and sources down in outline form as far as you have progressed 3) Print and hand in class Monday 4) Your assignment grade (0-10) will be based on subjective estimate of progress made so far. 1 2 Sensory Guidance and Oriented Behavior How organisms respond to external stimuli: ORIENTATION: turning response, or oriented response guided by stimulus location or direction. RESPONSE SELECTION: choice of response behavior as appropriate to stimulus. Nearly every behavior has a component to it that involves orientation. Examples of Oriented Behavior Chemotaxis Chemical trail following Directional tactile sense Sensing compass directions Using landmarks and memory 3 4 How do organisms sense the direction of a stimulus? by detecting the incident direction of the stimulus using an array of detectors by measure of stimulus gradient with two simultaneous sensors Collective behavior of bacteria around a food source by comparing two sensors by successive comparison of a single comparison in time with a single sensor compared successively in time

2 Bacterial Chemotaxis Taxes Orientation relative to a stimulus direction Phototaxis: orientation toward the light Negative phototaxis: orientation away from the light no attractant cell tumbles attractant cell runs orientation of a planaria primitive photoreceptors provides some directional cue 7 8 Trail following in an ant Olfactory orientation to prey by a snake normal trail following one antenna, one removed. Snake (Vipera aspis) path of head movements tracks the pathway left by a mouse, recently dead by snake bite, which has been dragged across the 1x1 m arena. Dotted line: path of live mouse. Circle (hiding place of mouse). antennae crossed 9 10 Pheromone Sensing in Moths Paramecium has a directional tactile sense paramecium avoids contact by reversing direction of swimming

3 Electrophysiology of Paramecium Orientation to Vibration Sources microelectrode recording anterior stimulation posterior stimulation anterior: posterior: depolarize Ca++ hyperpolarize K+ From studies by R. Eckert Using the sun to orient flight Jaques Loeb s Model for Taxes informing dance is performed in the hive food is located at a distance from hive Loeb (1918) Mechanistic approach to animal orientation: taxes and kineses. Applies to numerous cases of sensory guidance: light, heat, odor, sound, gravity, electroreception. 15 Orientation in Digger Wasps the sun is used as the landmark the direction of the dance corresponds to the direction of food relative to that of the sun. Gravity is substituted 16 reference. Special Senses (Tinbergen and Kruyt, 1938) Insect eye: sensitive to polarized light. Pigment molecules are embedded in membrane at random. random Membranes are organized into structured microvilli. Digger wasp leaves nest and circles opening for 6 second. Pine cones are placed there during time when she is belowground Female returns to provide food. Pine cones have been moved. Thus, behavior is guided by learning. 17 Orientation of pigment in rhabdome now has a preferred alignment relative edge of microvilli. Senses polarized light. 18 3

4 Vertebrate Rod R. Wehner polarized light sensitive area of honey bee is essential to orientation to the sun s compass. Ommatidia in dorsal POL are sensitive to UV light. The rhabdom does not twist in this area (so the plane of the microvilli are aligned only in one direction) area retain polarization sensitivity. Other areas: twist destroys polarization sensitivity 19 Orientation in the desert ant, Cataglyphis bicolor 20 Land and Collett (1974): Visual chasing in flies A classic paper in neuroethology. Use of sun depends upon polarized light sensitivity in UV. Demonstrates visual guidance is controlled by angular position of target, target and by angular velocity of target across the retina. Eye is organized to match the pattern of sky polarization polarization. Ant gets intensity readout which is directionally sensitive. Demonstrates that males have fovea dorsal region of high velocity and temporal resolution How do electric fish locate sources?

5 25 Schluger and Hopkins (1986) 26 Schluger and Hopkins (1986) 5