1 NOVEMBER 1998
CEPHALOPOD CULTURE: PHYSIOLOGICAL, BEHAVIORAL AND ENVIRONMENTAL REQUIREMENTS
P.G. Lee, P.E. Turk, J.W. Forsythe, F.P. DiMarco
Cephaopods are remarkable among poikilotherms for their rapid growth rates (> 10% body weight/d and protein-dependent metabolism. Cephalopods grow at rates equal to homeothermic vertebrates, surpassing by far their main competitors, the pokilothermic vertebrate fishes. Their rapid growth rate (from 10-20 mg to > 2 kg in 159 d) is dependent on their carnivorous lifestyle with daily feeding rates averaging 20-40% body weight/d through most of their life cycle. Dietary lipid is utilized poorly and dietary protein supplies their highly aerobic metabolism. As a result, cephalopods produce ammonia rapidly and yet they are extremely sensitive to the nitrogen waste products. Currently, a computer automated control system monitors and controls all system functions (i e. flow rates, salinity, level pH and photoperiod). In addition, an automated denitrifying bioreactor is used to reduce nitrate and eliminate water exchanges. The culture of cephalopods in such low ammonia (< 0.01 ppm) and low nitrate (< 20 ppm) sea water has resulted in multiple laboratory generations. Implementation of artificial diets is also a current area of research; a surimi-like diet supplemented with purified proteins has been used to grow cephalopods at 33% of their normal growth rate. Behaviorally, cephalopods are visually stimulated predators but their chemical senses do play a role in food selection and ingestion. Nucleotides (e.g ATP, ADP) and the amino acid, proline are the most effective chemicals that elicit chemotaxis in octopuses and squids and they are incorporated into artificial diets. These advances in cephalopod culture are establishing reliable sources for these important biomedical research models and point to the possibility of commercial culture for food.
(National Resource Center for Cephalopods, Marine Biomedical Institute, University of Texas Medical Branch Galveston, Texas 77555-1163, USA)