1 / 18

Lecture 10 Bio 325

Lecture 10 Bio 325. Necks, tagmata petioles, peduncles and pedicels: wasps, spiders, katydids, fish Tagmosis : division of a metameric body into groups of segments specialized for a common purpose. Chaetopterus compared with Nereis and tagma for pumping water

chidi
Download Presentation

Lecture 10 Bio 325

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Lecture 10 Bio 325 Necks, tagmata petioles, peduncles and pedicels: wasps, spiders, katydids, fish Tagmosis: division of a metameric body into groups of segments specialized for a common purpose. Chaetopterus compared with Nereis and tagma for pumping water Form and function in fish swimming Snakes and retrograde body waves Crotaline movement

  2. Tiktaalik is technically a fish, complete with scales and gills — but it has the flattened head of a crocodile and unusual fins. It is evolving toward a terrestrial tetrapod. from last lecture: ‘a fish with a neck’ Thanks to Jennifer Shadoff

  3. Musing about necks Necking lovebirds Agapornis • Necks contribute to gathering sensory information with the head, e.g., directing eyes, scanning skies. Bird necks make bird heads really mobile and its adaptive. • Vertebrae in the neck (atlas, axis) ressemble a universal joint. Songbirds are constantly glancing about or cocking one eye skyward: alert for stooping hawks when out of cover. Jerky scanning movements characterize bird motor activity.  I suppose a bird with a sore neck has a special problem.

  4. Necks seem to relate to tagmata: grouping of metameres specialized for a common function; or perhaps a neck might be said to be a one-segment tagma. • Potter wasp petiole. • Two ‘necks’, one behind the head, and one between the thorax and abdomen: making both the abdomen and the head mobile re the thorax. • One might say there are 4 tagmata: thorax, head, abdomen and the petiole (a tagma of one segment. petiole Hymenoptera petioles provide tagma manoeverability

  5. Orthopteran Cyphoderris illustrates a segmented abdomen adapted for ventilation • When acoustic insects stridulate the abdomen telescopes in and out like a little bellows, ventilating the tracheal system. Just as we breathe more heavily under exertion, so the katydid shows more rapid abdominal movements when singing. The retention of segmentation in the abdomen of many insects relates to this ventilating function.

  6. Spiders evolved from serially segmented ancestors; they have two tagmata: cephalothorax/soma, opisthosoma/abdomen; intervening pedicel creates mobility of abdomen tip for creating silk structures. Maydianne Andrade

  7. Phylum Annelida: concentrates organic food* filtering it from silt and inorganic particles using mucus and a seawater current. Chaetopterus Lives in U-shaped secreted parchment tubes constructed in tidal flats; notopodia on 12th segment are wing-like, aliform, produced; epithelium of these wings is ciliated and richly supplied with glands that secrete mucus. Notopodia of segments 14, 15 and 16 are modified into circular fans that just fit against the tube walls. paired aliform notopodia suckerr parapodia fan notopodium

  8. The 3 fans are a tagma that functions as a pump: it creates a current of water within the U-shaped tube. Why 3 fans? Why not 2 or 4? Why not 1?

  9. Amphioxus is characterized by a serial repetition of muscle blocks used in its locomotion by body waves; it recalls fish which are similarly characterized by blocks of muscle ranged along their body. Fish (teleosts): streamlined body, bone-supported flexible fins, notochord early in development replaced by a series of bones, interlocking vertebrae, the vertebral column; axial musculature of zig-zag blocks of muscle, myotomes separated by myocommas: the phasing of their contraction creates locomotion by retrograde waves. krisweb

  10. Assigned reading • Webb, Paul W. 1984. Form and function in fish swimming. Scientific American 251: 58-68. • “As is true of any solid body that is being propelled, the forward motion of the fish is the net result of the forces that tend to advance it and the forces that tend to retard it. In the case of the fish the impelling force is the thrust generated by the swimming movements. The retarding forces come from inertial resistance or from the drag of the water.” • This paper makes important points about adaptive differences in fish shape, undulatory vs oscillatory motion, development of thrust etc.

  11. dorsal acceleration PIKE caudal Threemain swimming functions anal pectoral pelvic manoevering cruising narrow necking peduncle TUNA

  12. Oscillatory vs undulatory motion • Undulatory: “a wave passes along the propulsive structure”; body, fin. • Two types of structure in fish can undulate: 1) body and caudal fin acting as a single unit; 2) deeply attached fins. Salmon uses 1); knifefish is propelled by a long –based undulatory RIBBON FIN on its ventral surface.

  13. Undulation stylesHow much of body oscillates, How much stays stable (more or less)Some classifications 1. anguilliform: eels, sea snakes undulate entire body, largest head displacement (same as snake ‘serpentine movement’ 2. subcarangiform: cod, salmonids: undulation involves more body than just peduncle and tail 3. carangiform: oscillating only tail fin and peduncle 4. Tunniform: tunas etc. Mackerell

  14. Retrograde body wave pushes back against the water; creating a reaction force (see normal force in drawing) resolvable into two vectors: one directed lateral to the direction of progress and the other thrust, directed straight forward, propelling the animal. Lateral forces of the right and left sides of the body wave tend to cancel out, but some lateral force effect may be seen in the side to side swinging of the head. ‘Propulsive element’: imagine a small segment of body and consider its behaviour. 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. “Rear elements travel faster than forward ones and the caudal inclination of the elements toward the rear is greater than the inclination of the elements toward the head.”

  15. From fish swimming in water to snakes in water, to snakes on land Boundary Waters BWCA Equisearch Matthieu Billaud

  16. Serpentine undulatory movement requires contact points where thrust can be obtained; animal uses prominences in irregular substrate to push against: only some parts of its body make contact , whereas underwater all its body makes contact. Albertawow.com

  17. Sidewinders Only certain portions of the body wave are placed in contact with the substratum

  18. Crotaline or ‘side-winding’ movement in snakes Challenging old test question: Could a snake employ sidewinding underwater?

More Related