The Uptake of Inorganic Electrolytes by the Crayfish

Abstract

1. Reasons are given for believing that the uptake of Na+, Cl-, and NaCl by the crayfish occurs through the gills. 2. A crayfish in fresh water, with a Cl concentration of about 0.2 mEq./l., can) by active Cl absorption, compensate entirely for Cl lost in the urine. 3. The carbonic anhydrase activity of the gills is markedly higher than that of other tissues of the crayfish, but the equivalent CO2 output of the crayfish is far in excess of the equivalent Cl absorption per unit time and weight and thus fails to warrant the supposition that Cl absorption is of respiratory importance. 4. The carbonic anhydrase activity of the soft integument of the lobster, before and after molting, and of the hypodermis of the hard-cuticled animal is almost identical and of the same order as that of other tissues of the lobster. 5. The concentration of the electrolytes was about 7.5 mEq./l.; i.e., considerably lower than in the blood of the crayfish. Cl- can be taken up independently of the complementary cation. Na+ can be taken up independently of the complementary anion. K+ and SO4= are not taken up at all. In pure NaCl, the Na+ and Cl- are absorbed evidently largely together. Ca++ is absorbed only in newly molted animals and in animals preparing to molt but is not absorbed by hard-cuticled animals not preparing to molt. Ca++ is taken up independently of Cl- in pure CaCl2. 6. Newly molted animals absorb Ca++ at a rate exceeding that of the absorption of other absorbable ions (Na+ and Cl-) in the same equivalent concentration. 7. A crayfish utilizes the Ca++ in fresh water in the calcification of its cuticle. Since the animal does not swallow water, the Ca++ must enter through the exterior. Reasons are given for believing that, unlike Na+ and Cl-, Ca++ is absorbed directly from the exterior by the integument and does not enter the body through the gills. 8. During molting, only about 4 per cent of the raw ash and 2.3 per cent of the organic material of the old cuticle is resorbed.

Distribution and Characterization of Ion Transporting and Respiratory Filaments in the Gills of Procambarus clarkii

“…Crayfish, like the euryhaline brachyurans in dilute media, exist in a hypoosmotic medium, and must maintain their ion balance by actively transporting electrolytes across the gills (Maluf, 1940;Bryan, 1959;Shaw, 1960a. b;Ehrenfeld, 1974).…”

“…This investigation was therefore directed at determining within a single filament, within a single gill, and among gills the distribution and frequency of the two types of epithelia of the freshwater crayfish Procambarus chirkii. The methods employed in this study were silver staining (Maluf, 1940), an indicator of ion transporting tissue; transmission electron microscopy (TEM), which reveals the striking difference between the morphology of the two types of epithelia; analysis for Na, K-ATPase, an effector of ion movement; and measurement of transepithelial potentials in individual filaments, which reflects possible differences in transport or permeability of the combined epithelial and cuticular layers.…”

Ionic permeabilities of the gill lamina cuticle of the crayfish, Astacus leptodactylus (E).

“…Fresh-water decapods such as the crayfish have to cope with high ionic concentration gradients. Krogh (1939), Maluf (1940) and Schmidt-Nielsen (1941) have shown that these animals are able to selectively take up ions from very dilute media. The silver-staining technique supports the idea that the gills are the main site of ionic exchanges (Lockwood, Bolt & Dawson, 1982).…”

Four Functional Filaments of the Freshwater Crayfish Cherax Tenuimanus (Decapoda: Parastacidae)

“…The functional differences in the Price et al (1995) study were determined by Ag staining, which indicates areas of ion-transporting epithelia (Koch, 1934;Maluf, 1940), with some limited support from transmission electron microscope studies of ultrastructural cell detail. However, Price et al (1995) indicated that not all filaments stained with Ag with an all-or-none response, as previously indicated by Dickson et al (1991) in their studies on Procambarus clarkii (Girard, 1852).…”