Skip to main content Accessibility help
×
Home

Physiological adaptations of the living agnathans

  • M. W. Hardisty (a1), I. C. Potter (a2) and R. W. Hilliard (a2)

Abstract

The modes of life and environments of the extant agnathans (cyclostomes) are discussed in relation to their adaptations to temperature, light, oxygen and salinity. As their antitropical distribution indicates, both hagfishes and lampreys are cold water groups. Since hagfishes live in deeper waters than lampreys, they are not exposed to the marked seasonal changes in temperature and light which influence major events in the lamprey life cycle. Both groups tend to be nocturnally active, either burrowing during daylight as in the case of larval lampreys (ammocoetes) and most hagfishes, or showing cryptic behaviour as in the case of adult lampreys. Olfaction plays a major part in the location of prey, presumably aided in adult lampreys by their eyes and sensitive electrosensory system. Rates of standard oxygen consumption, ventilatory frequency and heart rate of adult lampreys increase at night. Standard oxygen consumption is relatively low in ammocoetes (as it also is in hagfishes) but increases markedly during metamorphosis into the adult lamprey. Ammocoetes and hagfishes, and to a lesser extent adult lampreys, are resistant to reduced environmental oxygen tensions. Differences in the oxygen dissociation curves of ammocoetes, adult lampreys and hagfishes can be related to differences in the characteristics of their monomeric haemoglobins and their environments and modes of life. The extraordinary tolerance of the hagfish heart to hypoxia is a reflection of a robust capacity for glycolysis, an LDH isozyme geared towards anaerobic functioning and a low work output. The hagfishes, which are restricted to marine waters, are osmoconformers. The osmolality of their blood, which is almost wholly attributable to inorganic ions, is virtually identical to that of full strength sea water (c. 1000 mOsmkg−1). By contrast, the osmolality of the blood of larval and adult lampreys when in fresh water is only 205-260 mOsm kg−1, i.e. about one quarter to one fifth of those of hagfish, and these rise only to 240-270 mOsm kg−1 in the adults of anadromous lampreys in sea water. The regulation of ions by adult lampreys is achieved by mechanisms similar to those adopted by teleosts. The implications of the contrasting ionic and osmotic physiology of the two living groups of agnathans are discussed in relation to their possible environmental history and against the background of their Carboniferous fossil representatives.

Copyright

References

Hide All
Aldridge, R. J., Briggs, D. E. G., Clarkson, E. N. K. & Smith, P. 1986. The affinities of condonts—new evidence from the Carboniferous of Edinburgh, Scotland. LETHAIA 19, 279–91.
Alt, J. M., Stolte, H., Eisenbach, G. M. & Walvig, F. 1980. Renal electrolyte and fluid excretion in the Atlantic hagfish Myxine glutinosa. J EXP BIOL 91, 323–30.
Bardack, D. 1985. Les premiers fossiles de hagfish (Myxiniformes) et Enteropneusta (Hemichordata) depots de la faune (Pennsylvanienne) de Mazon Creek dans l'IIIinois, USA. BULL SOC HIST NAT AUTUN (FRANCE) 116, 97.
Bardack, D. & Richardson, E. S. 1977. New agnathous fishes from the Pennsylvanian of Illinois. FIELDIANA GEOL 33, 489510.
Bardack, D. & Zangerl, R. 1971. Lampreys in the fossil record. In Hardisty, M. W. & Potter, I. C. (eds) The Biology of Lampreys 1, 6784. London: Academic Press.
Bartels, H. & Welsch, U. 1986. Mitochondria-rich cells in the gill epithelium of cyclostomes: a thin section and freeze fracture study. In Uyeno, T., Arai, R., Taniuchi, T. & Matsuura, K. (eds) Indo-Pacific Fish Biology: Proceedings of the Second International Conference on Indo-Pacific fishes, 5872. Tokyo: Ichthyological Society of Japan.
Beamish, F. W. H. 1973. Oxygen consumption of adult Petromyzon marinus in relation to body weight and temperature. J FISH RES BD CAN 30, 1367–70.
Beamish, F. W. H. 1974. Swimming performance of adult sea lampreys in relation to weight and temperature. TRANS AM FISH SOC 103, 355–58.
Beamish, F. W. H. 1980. Osmoregulation in juvenile and adult lampreys. CAN J FISH AQUAT SCI 37, 1739–50.
Beamish, F. W. H., Strachan, P. D. & Thomas, E. 1978. Osmotic and ionic performance of the anadromous sea lamprey, Petromyzon marinus. COMP BIOCHEM PHYSIOL 60A, 435–43.
Beamish, F. W. H. & Mookherjii, P. S. 1964. Respiration of fishes with special emphasis on standard oxygen consumption. CAN J ZOOL 42, 161–75.
Bird, D. J., Lutz, P. L. & Potter, I. C. 1976. Oxygen dissociation curves of the blood of larval and adult lampreys (Lampetra fluviatilis). J EXP BIOL 65, 449–58.
Bird, D. J. & Potter, I. C. 1983. Changes in the fatty acid composition of triacylglycerols and phospholipids during the life cycle of the lamprey Geotria australis Gray. COMP BIOCHEM PHYSIOL 75B, 3141.
Bloom, G., Östlund, E. & Fänge, R. 1963. Functional aspects of the cyclostome heart in relation to recent structural findings. In Brodal, A. & Fänge, R. (eds) The Biology of Myxine, 317–39. Oslo: Universitetsforlaget.
Bodznick, D. & Preston, D. G. 1983. Physiological characterization of electroreceptors in the lamprey Ichthyomyzon unicuspis and Petromyzon marinus. J COMP PHYSIOL 152A, 209–18.
Brittain, T. & Wells, R. M. G. 1986. Characterization of the changes in the state of aggregation induced by ligand binding in the hemoglobin system of a primitive vertebrate, the hagfish Eptatretus cirrhatus. COMP BIOCHEM PHYSIOL 85A, 785–90.
Bull, J. M. & Morris, R. 1967. Studies on freshwater osmoregulation in the ammocoete larva of Lampetra planeri (Bloch). 1. Ionic constituents, fluid compartments, ionic compartments and water balance. J EXP BIOL 47, 485–94.
Bullock, T. H. 1986. Significance of findings on electroreception for general neurobiology. In Bullock, T. H. & Heiligenberg, W. (eds) Electroreception, 651–74. New York: Wiley Interscience.
Burggren, W., Johansen, K. & McMahon, B. 1985. Respiration in phyletically ancient fishes. In Foreman, R. E., Gorbman, A., Dodd, J. M. & Olsson, R. (eds) Evolutionary Biology of Primitive Fishes, 217–52. New York: Plenum Press.
Cholette, C., Gagnon, A. & Germain, P. 1970. Isosmotic adaptations in Myxine glutinosa L. I. Variations of some parameters and the role of the amino acid pool of the muscle cells. COMP BIOCHEM PHYSIOL 33A, 333–46.
Claridge, P. N., Potter, I. C. & Hughes, G. M. 1973. Circadian rhythms of activity, ventilatory frequency and heart rate in the adult river lamprey, Lampetra fluviatilis. J ZOOL LONDON 171, 239–50.
Claridge, P. N. & Potter, I. C. 1975. Oxygen consumption, ventilatory frequency and heart rate of lampreys (Lampetra fluviatilis) during their spawning run. J EXP BIOL 63, 193206.
Cole, W. C. & Youson, J. H. 1981. The effect of pinealectomy, continuous light, and continuous darkness on metamorphosis of anadromous Sea Lamprey, Petromyzon marinus L. J EXP ZOOL 218, 387404.
Cossins, A. R. & Bowler, K. 1987. Temperature biology of animals. London: Chapman and Hall.
Dawson, J. A. 1963. The oral cavity, the ‘jaws’ and the horny teeth of Myxine glutinosa. In Brodal, A. & Fänge, R. (eds) The Biology of Myxine, 231235. Oslo: Universitetsforlaget.
Eddy, J. M. P. 1972. The pineal complex. In Hardisty, M. W. & Potter, I. C. (eds) The Biology of Lampreys 2, 91103. London: Academic Press.
Enequist, P. 1937. Das Bachneunauge als ökologische Modification des Flüssneunauges. Über die Flüss- und Bachneunaugen Schwedens. ARK ZOOL 29, 122.
Evans, D. H. 1984. Gill Na+/H+ and exchange systems evolved before the vertebrates entered freshwater. J EXP BIOL 113, 465–69.
Fänge, R. 1985. Regulation of blood and body fluids in primitive fish groups. In Foreman, R. E., Gorbman, A., Dodd, J. M. & Olsson, R. (eds) Evolutionary Biology of Primitive Fishes, 253–73. New York: Plenum Press.
Farmer, G. J., Beamish, F. W. H. & Robinson, G. A. 1975. Food consumption of the adult landlocked sea lamprey, Petromyzon marinus L. COMP BIOCHEM PHYSIOL 50A, 753–7.
Febry, R. & Lutz, P. 1987. Energy Partitioning in fish: the activity-related cost of osmoregulation in a euryhaline cichlid. J EXP BIOL 128, 6385.
Fernholm, B. 1974. Diurnal variations in the behaviour of the hagfish, Eptatretus burgeri. MAR BIOL 27, 351–66.
Fernholm, B. & Holmberg, K. 1974. The eyes in three genera of hagfish, Eptatretus, Paramyxine and Myxine—a case of degenerative evolution. VISION RES 15, 253–59.
Forey, P. L. 1984. Yet more reflections on Agnathan-gnathostome relationships. J VERT PALAEONTOL 4, 330–43.
Franz, V. 1932. Auge und Akkommodation von Petromyzon (Lampetra) fluviatilis L. ZOOL JB 52, 118–78.
Galloway, R., Potter, I. C.Macey, D. J., & Hilliard, R. W. 1987. Oxygen consumption and responses to hypoxia in the ammocoetes of the Southern Hemisphere lamprey, Geotria australis. FISH PHYSIOL BIOCHEM 3, 6372.
Gladner, J. A., Lewis, M. S. & Chung, S. I. 1981. Molecular properties of lamprey fibrinogen. J BIOL CHEM 256, 1772–81.
Goodman, M., Miyamoto, M. M. & Czelusniak, J. 1987. Pattern and process in vertebrate phylogeny revealed by coevolution of molecules and morphologies. In Patterson, C. (ed.) Molecules and Morphology in Evolution: Conflict or Compromise, 141–76. Cambridge: Cambridge University Press.
Griffith, R. W. 1985. Habitat, phylogeny and the evolution of osmoregulatory strategies in primitive fishes. In Foreman, R. E., Gorbman, A., Dodd, J. M., & Olsson, R. (eds) Evolutionary Biology of Primitive Fishes, 6980. New York: Plenum Press.
Griffith, R. W. 1987. Freshwater or marine origin of the vertebrates? COMP BIOCHEM PHYSIOL 87A, 523–31.
Gustafson, A. 1935. On the biology of Myxine glutinosa. ARK ZOOL 28, 128.
Hansen, C. A. & Sidell, B. D. 1983. Atlantic hagfish muscle, metabolic basis of tolerance to anoxia. AM J PHYSIOL 244, 356–62.
Hardisty, M. W. 1956. Some aspects of osmotic regulation in lampreys. J EXP BIOL 33, 431–47.
Hardisty, M. W. 1957. Osmotic conditions during the embryonic and early larval life of the brook lamprey (Lampetra planeri). J EXP BIOL 34, 2325.
Hardisty, M. W. 1961. Studies on an isolated spawning population of the brook lamprey (Lampetra planeri). J ANIM ECOL 30, 339–55.
Hardisty, M. W. 1979. Biology of Cyclostomes. London: Chapman & Hall.
Hardisty, M. W. 1982. Lampreys and hagfishes: an analysis of cyclostome relationships. In Hardisty, M. W. & Potter, I. C. (eds) The Biology of Lampreys 4B, 165259. London: Academic Press.
Hardisty, M. W., Zelnik, P. R. & Wright, V. C. 1976. The effects of hypoxia on blood sugar levels and on the endocrine pancreas, interrenal and chromaffin tissues of the lamprey, Lampetra fluviatilis L. GEN COMP ENDOCRINOL 28, 184204.
Hardisty, M. W. & Potter, I. C. 1971a. The general biology of adult lampreys. In Hardisty, M. W. & Potter, I. C. (eds) The Biology of Lampreys 1, 127206. London: Academic Press.
Hardisty, M. W. & Potter, I. C. 1971b. The behaviour, ecology and growth of larval lampreys. In Hardisty, M. W. & Potter, I. C. (eds) The Biology of Lampreys 1, 85125. London: Academic Press.
Hill, B. J. & Potter, I. C. 1970. Oxygen consumption in ammocoetes of the lamprey Ichthyomyzon hubbsi Raney. J EXP BIOL 53, 4757.
Hilliard, R. W., Potter, I. C. & Macey, D. J. 1985. The dentition and feeding mechanism in adults of the Southern Hemisphere lamprey Geotria australis Gray. ACTA ZOOL STOCKH 66, 159170.
Hubbs, C. L. & Potter, I. C. 1971. Distribution, phylogeny and taxonomy. In Hardisty, M. W. & Potter, I. C. (eds) The Biology of Lampreys 1, 165. London: Academic Press.
Janvier, P. 1981. The phylogeny of the Craniata, with particular reference to the significance of fossil “Agnathans”. J VERT PALEONTOL 1, 121–59.
Janvier, P. 1986. Les nouvelles conceptions de la phylogenie et de la classification des “Agnathes” et des Sarcopterygians. OCEANIS 12, 123–36.
Janvier, P. & Blieck, A. 1979. New data on the internal anatomy of the Heterostraci (Agnatha), with general remarks on the phylogeny of the Craniata. ZOOL SCR 8, 287–96.
Janvier, P. & Lund, R. 1983. Hardistiella montanensis N. Gen. et Sp. (Petromyzontida) from the Lower Carboniferous of Montana, with remarks on the affinities of the lampreys. J VERT PALEONTOL 2, 407–13.
Johansen, K., Lenfant, C. & Hanson, D. 1973. Gas exchange in the lamprey, Entosphenus tridentatus. COMP BIOCHEM PHYSIOL 44A, 107–19.
Joss, J. M. P. 1977. Hydroxyindole-O-methyltransferase (HIOMT) activity and the uptake of 3H-melatonin in the lamprey, Geotria australis Gray. GEN COMP ENDOCR 31, 270–75.
Joss, J. M. P. & Potter, I. C. 1982. Circadian rhythms. In Hardisty, M. W. & Potter, I. C. (eds) The Biology of Lampreys 4B, 117–35. London: Academic Press.
Korolewa, N. W. 1964. [Water respiration of lamprey and survival in a moist atmosphere]. ISV VSES NAUCHNO-ISSLED INST OZERN RECHN RYB KHOZ 58, 186–90 [in Russian].
Krejsa, R. J. & Slavkin, H. C. 1987. The hagfish-conodont connection. J DENTAL RES 66, 144.
Lemons, D. E. & Crayshaw, L. I. 1978. Temperature regulation in Pacific lamprey. FED PROC 37, 929.
Lewis, S. V. 1980. Respiration in lampreys. CAN J FISH AQUAT SCI 37, 1711–22.
Lewis, S. V. & Potter, I. C. 1977. Oxygen consumption during the metamorphosis of the parasitic lamprey, Lampetra fluviatilis (L.) and its non-parasitic derivative, Lampetra planeri (Bloch). J EXP BIOL 69, 187–98.
Logan, A. G., Moriarty, R. J. & Rankin, J. C. 1980. A micropuncture study of kidney function in the river lamprey adapted to freshwater. J EXP BIOL 85, 137–47.
Løvtrup, S. 1977. The phytogeny of Vertebrata. New York: Wiley & Sons.
Lund, R. & Janvier, P. 1986. A second lamprey from the Lower Carboniferous of Bear Gulch, Montana (USA). GEOBIOS 19, 647652.
Lutz, P. 1975. Adaptive and evolutionary aspects of the ionic content of fishes. COPEIA 1975, 369–73.
Macallum, A. H. 1910. The inorganic composition of the blood in vertebrates and its origin. PROC R SOC LONDON B83, 602–04.
Macey, D. J. & Potter, I. C. 1978. Lethal temperatures of ammocoetes of the Southern Hemisphere lamprey, Geotria australis Gray. ENVIRON BIOL FISHES 3, 241–43.
Macey, D. J. & Potter, I. C. 1982. The effect of temperature on the oxygen dissociation curves of whole blood of larval and adult lampreys (Geotria australis). J EXP BIOL 97, 253–61.
Maisey, J. G. 1986. Heads and tails: a chordate phylogeny. CLADISTICS 2, 201–56.
Mallatt, J. 1984. Early vertebrate evolution: pharyngeal structure and the origin of gnathostomes. J ZOOL LONDON 204, 169–83.
Mallatt, J., Conley, D. M. & Ridgway, R. L. 1987. Why do hagfish have gill ‘chloride cells’ when they need not regulate plasma NaCl concentration?. CAN J ZOOL 65, 1956–65.
Manion, P. J. & Smith, B. R. 1978. Biology of larval and metamorphosing sea lampreys, Petromyzon marinus, of the 1960 year class in the Big Garlic river, Michigan. Part II, 1966–72. GT LAKES FISH COMM TECH REP 30, 135.
Manwell, C. 1963. The blood proteins of cyclostomes. In Brodal, A. & Fänge, R. (eds) The Biology of Myxine, 372455. Oslo: Universitetsforlaget.
Mathers, J. S. & Beamish, F. W. H. 1974. Changes in serum osmotic and ionic concentration in land-locked Petromyzon marinus. COMP BIOCHEM PHYSIOL 49A, 677–88.
McCauley, R. W., Reynolds, W. W. & Huggins, N. H. 1977. Photokinesis and behavioural thermoregulation in adult sea lampreys (Petromyzon marinus). J EXP ZOOL 202, 431437.
McFarland, W. N. & Munz, F. W. 1965. Regulation of body weight and serum composition of hagfish in various media. COMP BIOCHEM PHYSIOL 14A, 383–98.
McInerney, J. E. 1974. Renal sodium reabsorption in hagfish, Eptatretus stoutii. COMP BIOCHEM PHYSIOL 49A, 273–80.
McInerney, J. E. & Evans, D. C. 1970. Habitat characteristics of the Pacific hagfish, Polistotrema stoutii. J FISH RES BD CAN 27, 966–68.
Morris, R. 1958. The mechanism of marine osmoregulation in the lampern (Lampetra fluviatilis) and the causes of its breakdown during the spawning migration. J EXP BIOL 35, 649–65.
Morris, R. 1980. Blood composition and osmoregulation in ammocoete larva. CAN J FISH AQUAT SCI 37, 1665–79.
Munz, F. W. & Morris, R. 1965. Metabolic rate of the hagfish Eptatretus stouti (Lockington) 1878. COMP BIOCHEM PHYSIOL 16, 15.
Newth, D. R. & Ross, D. M. 1955. On the reaction to light of Myxine glutinosa L. J EXP BIOL 32, 421.
Nikinmaa, M. & Weber, R. E. 1984. Hypoxic acclimation in the lamprey, Lampetra fluviatilis; organismic and erythrocytic responses. J EXP BIOL 109, 109–20.
Piavis, G. W. 1971. Embryology. In Hardisty, M. W. & Potter, I. C. (eds) The Biology of Lampreys 1, 361400. London: Academic Press.
Pickering, A. D. & Morris, R. 1970. Osmoregulation of Lampetra fluviatilis and Petromyzon marinus (Cyclostomata) in hypertonic solutions. J EXP BIOL 53, 231–43.
Potter, I. C. 1980a. The ecology of larval and metamorphosing lampreys. CAN J FISH AQUAT SCI 37, 16411657.
Potter, I. C. 1980b. The Petromyzoniformes with particular reference to paired species. CAN J FISH AQUAT SCI 37, 15951615.
Potter, I. C., Hill, B. J. & Gentleman, S. 1970. Survival and behaviour of ammocoetes at low oxygen levels. J EXP BIOL 53, 5973.
Potter, I. C., Lord, Percy R., Barber, D. L. & Macey, D. J. 1982. The morphology, development and physiology of blood cells. In Hardisty, M. W. & Potter, I. C. (eds) The Biology of Lampreys 4A, 233–92. London: Academic Press.
Potter, I. C. & Hilliard, R. W. 1987. A proposal for the functional and phylogenetic significance of differences in the dentition of lampreys. J ZOOL LONDON 212, 513–37.
Potter, I. C. & Huggins, R. J. 1973. Observations on the morphology, behaviour and salinity tolerance of downstream migrating river lampreys (Lampetra fluviatilis). J ZOOL LONDON 169, 365–79.
Potter, I. C. & Rogers, M. J. 1972. Oxygen consumption in burrowed and unburrowed ammocoetes of Lampetra planeri (Bloch). COMP BIOCHEM PHYSIOL 41A, 427–32.
Prosser, C. L., Ayers, J., Green, E. & Nelson, D. 1985. Evolution of temperature regulation and of constancy of function (homeokinesis) at different temperatures. In Foreman, R. E., Gorbman, A., Dodd, J. M. & Olsson, R. (eds) Evolutionary Biology of Primitive Fishes, 203–15. New York: Plenum Press.
Raven, J. A. 1985. Comparative physiology of plant and arthropod land adaptation. PHILOS TRANS R SOC LONDON B309, 273–88.
Reynolds, W. W. & Casterlin, M. E. 1978. Behavioural thermoregulation by ammocoete larvae of the sea lamprey (Petromyzon marinus) in an electronic shuttlebox. HYDROBIOLOGIA 61, 145–47.
Riegel, J. A. 1986. Hydrostatic pressures in the glomeruli and renal vasculature of the hagfish, Eptatretus stouti. J EXP BIOL 123, 359–71.
Riggs, A. 1972. The haemoglobins. In Hardisty, M. W. & Potter, I. C. (eds) The Biology of Lampreys 2, 261–86. London: Academic Press.
Robertson, J. D. 1954. The chemical composition of the blood of some aquatic chordates, including members of the Tunicata, Cyclostomata and Osteichthyes. J EXP BIOL 31, 424–42.
Robertson, J. D. 1957. The habitat of the earliest vertebrates. BIOL REV 32, 156–87.
Robertson, J. D. 1974. Osmotic and ionic regulation in cyclostomes. In Florkin, M. & Scheer, B. T. (eds) Chemical Zoology 8, 149–93. New York: Academic Press.
Robertson, J. D. 1976. Chemical composition of the body fluids and muscle of the hagfish, Myxine glutinosa, and the rabbit fish Chimaera monstrata. J ZOOL LONDON 178, 261–77.
Robertson, J. D. 1984. The composition of blood plasma and parietal muscle of Oslo Fjord eels [Anguilla anguilla (L.)] and the river lamprey [Lampetra fluviatilis (L.)]. COMP BIOCHEM PHYSIOL 77A, 431–39.
Ross, D. M. 1963. The sense organs of Myxine glutinosa. In Brodal, A. & Fänge, R. (eds) The Biology of Myxine, 150–60. Oslo: Universitetsforlaget.
Rovainen, C. M. 1982. Neurophysiology. In Hardisty, M. W. & Potter, I. C. (eds) The Biology of Lampreys 4A, 1136. London: Academic Press.
Ruben, J. A. & Bennett, A. F. 1980. Antiquity of the vertebrate patterns of activity metabolism and its possible vertebrate origins. NATURE 286, 886–88.
Rubinson, K., Ripps, H., Witkovsky, P. & Kennedy, M. C. 1977. Retinal development in the lamprey, Petromyzon marinus. SOC NEUROSCI ABSTR 3, 575.
Rudy, P. P. & Wagner, R. C. 1970. Water permeability in the Pacific hagfish, Polistotrema stouti and the staghorn sculpin, Leptococcus armatus. COMP BIOCHEM PHYSIOL 34, 339403.
Runnegar, B. 1982. The Cambrian explosion: animals or fossils? J GEOL SOC AUST 29, 395411.
Rutten, M. G. 1970. The history of atmospheric oxygen. SPACE LIFE SCI 2, 517.
Schaeffer, B. & Thomson, K. S. 1980. Reflections on agnathan-gnathostome relationships. In Jacobs, L. L. (ed.) Aspects of Vertebrate History: Essays in Honor of Edwin Harris Colbert, 1933. Flagstaff: University of Northern Arizona Press.
Schmidt-Nielsen, K. 1983. Animal Physiology. Cambridge: Cambridge University Press.
Shelton, R. G. J. 1978. On the feeding of the hagfish, Myxine glutinosa, in the North Sea. J MAR BIOL ASSOC UK 58, 8186.
Sheren, S. B., Eikenberry, E. F., Broek, D. L., van, der Rest M., Doering, T., Kelly, J., Hardt, T. & Brodsky, B. 1986. Type II collagen of lamprey. COMP BIOCHEM PHYSIOL 85B, 514.
Sidell, B. D. 1983. Cardiac metabolism in the Myxinidae; physiological and phylogenetic considerations. COMP BIOCHEM PHYSIOL 76A, 495505.
Sidell, B. D. & Beland, K. F. 1980. Lactate dehydrogenase of Atlantic hagfish. Physiological and evolutionary implications of a primitive heart isozyme. SCIENCE 207, 769–70.
Smith, H. W. 1932. Water regulation and its evolution in the fishes. Q REV BIOL 7, 126.
Smith, K. L. & Hessler, R. R. 1974. Respiration of benthopelagic fishes: in situ measurements at 1230 metres. SCIENCE 184, 72–3.
Steffensen, J. F., Johansen, K., Sindberg, C. D., Sorensen, J. H. & Moller, J. L. 1984. Ventilation and oxygen consumption in the hagfish, Myxine glutinosa L. MAR BIOL ECOL 84, 173–78.
Steven, D. M. 1955. Experiments on the light sense of the hag, Myxine glutinosa L. J EXP BIOL 32, 2238.
Strahan, R. 1963. The behaviour of myxinoids. ACTA ZOOL STOCKH 24, 130.
Wells, R. M. G., Forster, M. E., Davison, W., Taylor, H. H., Davie, P. S. & Satchell, G. H. 1986. Blood oxygen transport in the free-swimming hagfish, Eptatretus cirrhatus. J EXP BIOL 123, 4353.
Yalden, D. W. 1985. Feeding mechanisms as evidence for cyclostome monophyly. ZOOL J LINN SOC 84, 291300.

Keywords

Physiological adaptations of the living agnathans

  • M. W. Hardisty (a1), I. C. Potter (a2) and R. W. Hilliard (a2)

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed