Lecture 8, Jan. 27

1. Lecture 8, Jan. 27 Scutigera Adhesive locomotion: walking on glue -- sliding on snot Sidewinding and serpentine snakes Fish swimming shapes Jumping onto dogs

2. Arthropod of the day: Class Chilopoda: house centipede Legs moved in a metachronal stepping wave: one step-cycles after another -- just out of phase; opposite is a synchronal wave: all in synchrony. The movement of Nereisparapodia during swimming is metachronal.

3. sidewinders Only certain portions of the body wave are placed in contact with the substratum

4. Crotaline movement in snakes The snake puts down body ‘segments’ at B and lifts them up at A [tractor]; the snake is not sliding its ‘segments’ along the ground What would happen when a crotaline snake tried to employ sidewinding in water?

5. Fish swimming Webb, Paul W. 1984. Form and function in fish swimming. Scientific American 251: 58-68. Sfakiotakis M., Lane D.M., Davies J.B.C. 1999. Review of fish swimming modes for aquatic locomotion. IEEE Journal of Oceanic Engineering 24: 237-252

6. Thrust: forces that tend to advance the fish; drag: forces that tend to retard it Retrograde body wave pushes back against the water; creates a reaction force resolvable into two components: one lateral and the other propelling the animal forward: thrust; lateral forces of the right and left sides tend to cancel out. Propulsive element: small segment of body Inclination of reaction force is toward the head The farther back a propulsive element is located the steeper this incline toward the head; thus more of the reaction force is thrust as one moves posteriorly out along the tail. Rearward elements are moving through a greater displacement – in the same time – so they needs must go faster. Change medium to ‘pegs’: snake locomotion serpentine on land

7. Undulation and oscillation; ribbon fin;feathering, draw strokes, flexible canoe paddle. In oscillation a fin attached by a short peduncle (base) moves rapidly back and forth to propel without any wave motion. Diversity of fish body shapes relate to locomotion: corners of the triangle: tuna sustained cruising, strong ‘narrow necking’; butterfly fish for maneuvering, plate in water; pike or barracuda for acceleration.

8. Pedal locomotion in Gastropoda Mantle cavity has been converted into a lung: hence ‘pulmonate snails’ of which slugs are just one type; edges of mantle cavity sealed to back except for pneumostome opening; roof of mantle cavity vascularized, no gill. >16000 species. From Wikimedia Commons Arionater, black slug

10. Denny, M. 1980. The role of gastropod pedal mucus in locomotion. Nature 285: 160-161. See also: Barnes, Invert. Zool. 7thed, p. 363. Monotaxic and ditaxic species

11. The schnauzer and the blood-sucking ectoparasite Adaptiveness of flea side-to-side body flattening; flea setae (hairs) orientation

12. Rothschild, M. et al. 1973. The flying leap of the flea. Scientific American 222: 92-101

14. Rebound resilience of the protein resilin is 97% Fleas can jump 100 X its body length Accelerates from rest to 1 metre p sec in a distance of 0.4 mm; extends its legs in about 8/1000 th of a second. Power rate of doing work Resilin located in the pleural arch Energy loaded into pleural arch and held there by catches Release is by body width change.

15. The trochanteral depressor is located a relatively long way from the trochanter; it originates on the notum and inserts on the trochanter (B, C). The insertion is via a massive tendon-like apodeme and this attaches anterior to the (dicondylic) axis of the trochanteral rotation (see blue dots in A, B, C). So the contraction of the trochanteral depressor pulls the trochanter, rotating it forward on the coxa and extending it (= depressing it) against the substratum.