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Engulfing mechanics of fin whales
90-l
Abstracts
SESSION 12. GETTING
ALONG
IN THE WATER
SEAWEEDS IN DIFFERENT EXPOSURE REGIMES SHOW DIFFERING STIPE SHAPES AND MATERIAL PROPERTIES N. Dean Pentcheff Department of Zoology, University of California, Berkeley CA 94720 Stipes from seaweed populations in different wave regimes were examined for differences in mechanical and morphological properties expected to influence their chance of breakage due to wave forces. TWO species of seaweeds, Gracilaria foliifera (Rhodophyta: Gigartinales) and Saroassum filipendula (Phaeophyta: Fucales), both found in high and low wave exposure areas, were studied. Mechanical tests of the tissue combined with information on the stipe shape showed that the two species both demonstrate differences in the different exposure zones. These differences, however, are not the same for each species. In s. foliifera, the elastic modulus (E) is greater at the high exposure site; the reverse is true for 3. filipendula. Although the work to fracture (W) is significantly greater for 3. filipendula than for s* foliifera, there is little intraspecific difference. 9. foliifera flattens at high exposure; S. filipendula has a greater cross sectional area. Despite the numerous drfferences, bending properties and W are similar across exposure zones.
EFFECTS OF CALCIUM IONOPHOREAND PROTON IONOPHORESON THE VISCOSITY OF THE HOLOTHURIAN CATCH CONNECTIVE TISSUE Tatsuo Motokawa Department of Zoology, Duke University, Durham, NC 27706, USA. Catch connective tissues are characterized by the ability to change their Current hypothesis for the mechanical properties rapid1 under nervous control. cells in the tissue mechanism of the change is t K at a secretion from neurosecretory alters the ionic environment of the extracellular matrix to change the viscous interactions of matrix macromolecules. Because calcium and hydrogen ions are most possible candidates for the concentration change, the effects of calcium ionophore (A23 187) and proton ionophores (tetrachlorosalicylanilide (TCS) and monensin) were studied on the viscosity of the catch connective tissue in the body wall of a sea cucumber Holotnuria/eucospi/ofa Brandt. The normal viscosity was measured b a cre $.JI test while the dermis sample was immersed in artificial sea water (ASIv 1. IO- M TCS and monensm in ASW increased the viscosity by 5 times whereas 10m5M When Ca2+ was removed from ASW, these A23 187 did not affect the viscosity. ionophores caused no viscosity changes. Because lowering the H of the bathin media Increased the viscosity both in the presence and absence of Ca!I+, the effect o B proton ionophorqs 1s probably not through changing the extracellular pH but through affecting concencells through than ing the intracellular the sctivitie+s of vi+scosity-controllin tration of H or Na . The present resu 9 ts do not support t !?e idea that the cells contain large amount of Ca2+ or H in membrane-bound structures as a solution.
EHGULFLNG tlECHAHlCS OF FIN WHALES
Lisa Schichtel Orton Departmentof Zoology.DukeUniversity. Durham, N. C. 27707 Paul F. Brcdie Marine EcologyLaboratory, BedfordInstitute, Dartmouth, NovaScotia B2Y 4A2 The grooved throat wall of fin whales Pa/aeno,olefa ~h,vsa/us extends tremendously during feeding causing the whale to expand its profile from a cigar shape to the shape of an elongated, bloated tadpole. In this study we show that the ventral groove blubber associated with the engulfing feeding mechanism can be extended reversibly as much as four times its resting length in the circumferential direction, and one and one half times its resting length along the long axis of the body. The muscle in the throat wall can be extended reversibly up to three times its resting length. Both these tissues contain large amounts of microfibrillar elastin that may function in retracting the expanded buccal cavity. Calculations of forces contributing to the expansion of the buccal cavity show that the engulfing process in feeding can be powered solely by the speed of swimming.
Abstracts
SESSION 12. GETTING
ALONG
IN THE WATER
SEAWEEDS IN DIFFERENT EXPOSURE REGIMES SHOW DIFFERING STIPE SHAPES AND MATERIAL PROPERTIES N. Dean Pentcheff Department of Zoology, University of California, Berkeley CA 94720 Stipes from seaweed populations in different wave regimes were examined for differences in mechanical and morphological properties expected to influence their chance of breakage due to wave forces. TWO species of seaweeds, Gracilaria foliifera (Rhodophyta: Gigartinales) and Saroassum filipendula (Phaeophyta: Fucales), both found in high and low wave exposure areas, were studied. Mechanical tests of the tissue combined with information on the stipe shape showed that the two species both demonstrate differences in the different exposure zones. These differences, however, are not the same for each species. In s. foliifera, the elastic modulus (E) is greater at the high exposure site; the reverse is true for 3. filipendula. Although the work to fracture (W) is significantly greater for 3. filipendula than for s* foliifera, there is little intraspecific difference. 9. foliifera flattens at high exposure; S. filipendula has a greater cross sectional area. Despite the numerous drfferences, bending properties and W are similar across exposure zones.
EFFECTS OF CALCIUM IONOPHOREAND PROTON IONOPHORESON THE VISCOSITY OF THE HOLOTHURIAN CATCH CONNECTIVE TISSUE Tatsuo Motokawa Department of Zoology, Duke University, Durham, NC 27706, USA. Catch connective tissues are characterized by the ability to change their Current hypothesis for the mechanical properties rapid1 under nervous control. cells in the tissue mechanism of the change is t K at a secretion from neurosecretory alters the ionic environment of the extracellular matrix to change the viscous interactions of matrix macromolecules. Because calcium and hydrogen ions are most possible candidates for the concentration change, the effects of calcium ionophore (A23 187) and proton ionophores (tetrachlorosalicylanilide (TCS) and monensin) were studied on the viscosity of the catch connective tissue in the body wall of a sea cucumber Holotnuria/eucospi/ofa Brandt. The normal viscosity was measured b a cre $.JI test while the dermis sample was immersed in artificial sea water (ASIv 1. IO- M TCS and monensm in ASW increased the viscosity by 5 times whereas 10m5M When Ca2+ was removed from ASW, these A23 187 did not affect the viscosity. ionophores caused no viscosity changes. Because lowering the H of the bathin media Increased the viscosity both in the presence and absence of Ca!I+, the effect o B proton ionophorqs 1s probably not through changing the extracellular pH but through affecting concencells through than ing the intracellular the sctivitie+s of vi+scosity-controllin tration of H or Na . The present resu 9 ts do not support t !?e idea that the cells contain large amount of Ca2+ or H in membrane-bound structures as a solution.
EHGULFLNG tlECHAHlCS OF FIN WHALES
Lisa Schichtel Orton Departmentof Zoology.DukeUniversity. Durham, N. C. 27707 Paul F. Brcdie Marine EcologyLaboratory, BedfordInstitute, Dartmouth, NovaScotia B2Y 4A2 The grooved throat wall of fin whales Pa/aeno,olefa ~h,vsa/us extends tremendously during feeding causing the whale to expand its profile from a cigar shape to the shape of an elongated, bloated tadpole. In this study we show that the ventral groove blubber associated with the engulfing feeding mechanism can be extended reversibly as much as four times its resting length in the circumferential direction, and one and one half times its resting length along the long axis of the body. The muscle in the throat wall can be extended reversibly up to three times its resting length. Both these tissues contain large amounts of microfibrillar elastin that may function in retracting the expanded buccal cavity. Calculations of forces contributing to the expansion of the buccal cavity show that the engulfing process in feeding can be powered solely by the speed of swimming.