. The biology of marine animals. Marine animals; Physiology, Comparative. RESPIRATION 185 serves as a high-tension oxygen transport system only when the sand is covered by the sea, and the oxygen tension of water in its burrow is high (91). In Caudina and Anadara (Area), with corpuscular haemoglobin, 02 becomes available only at low tensions (8-10 mm). In two closely related holothurians, one, Cucumaria ebngata, possesses Hb, while another, C. saxicola, lacks it. The former is a mud-dweller, the latter lives among rocks, and the presence or absence of Hb appears to be correlated with availabil
. The biology of marine animals. Marine animals; Physiology, Comparative. RESPIRATION 185 serves as a high-tension oxygen transport system only when the sand is covered by the sea, and the oxygen tension of water in its burrow is high (91). In Caudina and Anadara (Area), with corpuscular haemoglobin, 02 becomes available only at low tensions (8-10 mm). In two closely related holothurians, one, Cucumaria ebngata, possesses Hb, while another, C. saxicola, lacks it. The former is a mud-dweller, the latter lives among rocks, and the presence or absence of Hb appears to be correlated with availability of oxygen. The possession of haemoglobin is exceptional in arthropods. Among entomostracans it is sometimes limited to parasitic species (parasitic 100 .0 80 ? 60 Arenicola. Hb PH7-5,19°C Nephthys Vascular Hb pH7 4, 15°C. £40 c: 10 15 20 Oxygen Tension (mm Hg) Fig. Comparison of Oxygen Dissociation Curves of Polychaete Haemoglobins, namely Vascular and Coelomic Haemoglobin of Nephthys hombergi and Vascular Haemoglobin of Arenicola marina The vertical dotted lines above the abscissa show the levels of oxygen tension in the interstitial water from the sand in which Nephthys lives, and in the residual water of exposed Arenicola burrows (from Jones (91).) copepods, cirripedes). In the brine shrimp Artemia salina, haemoglobin functions in oxygen transport when the animals are living in concentrated brines (such media have low oxygen content, about one-third that of sea water when saturated with air). Treatment with CO, leading to formation of carboxyhaemoglobin, significantly reduces oxygen consumption (external medium, salinity 195%0, 02 2 ). Artemia is an example of a species that gains or loses haemoglobin in response to low or high oxygen concentrations of the surrounding medium. The haemoglobins of Chirono- mus (tidal-pool and freshwater insects) have remarkably high oxygen affinities (tu<\ mm Hg), and function in oxygen-deficient environments (57, 66, 104
Size: 2049px × 1220px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, booksubjectmarineanimals, booksubjectphysiology
