Variations in urinary output of the lobster

✍ Scribed by Cheng, Jin-Hua ;Chang, Ernest S.

• Publisher: John Wiley and Sons
• Year: 1991
• Tongue: English
• Weight: 702 KB
• Volume: 260
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/jez.1402600303

✦ Synopsis

Abstract

Urinary rates were studied in cannulated juvenile lobsters. If animals were in intermolt and unfed, urinary rates were constant at daily rates of 2% and 20% of body weight in 100% and 75% seawater (SW), respectively. More than 4% of the body weight could be rapidly excreted as urine upon either feeding, forced drinking, or low salinity acclimation. These results indicate that the urinary bladders are usually filled with urine and that they are part of the body volume‐regulating system.

At ecdysis, however, urinary flow ceased when drinking rate increased, suggesting that the intermolt mechanism regulating body volume may have been altered. In 100% SW, drinking was necessary for lobsters to gain sufficient water to withdraw their claws at ecdysis. While in 75% SW, osmotic entry of water across the body surface alone was sufficient to permit a successful molt. These results indicate that water influx across the body surface may contribute to much of the water intake at ecdysis if the osmotic gradient is substantial and that the cessation of urinary flow contributes to the overall water balance at ecdysis.