Growth and Nutrition ofAplysia PunctataFeeding on a Variety of Marine Algae

Abstract

The growth rates ofAplysia punctataCuvier feeding on eight species of marine algae were found to decrease in the order:Plocamium > Enteromorpha > Ulva > Heterosiphonia > Cryptopleura > Delesseria > Laminaria.The brown alga,Desmarestia aculeata, was not eaten. Except forEnteromorphaandDesmarestia, this was also the order found for the feeding preference of sublittoralAplysia. Enteromorphawas eaten byAplysiain preference to all the other algae studied.No clearly defined trends in the concentrations of ash, protein, fat and carbohydrate in the seaweeds were found to account for these differences in growth rates. Absorption of total dry food matter was lowest from the algae giving the poorest growth (45 and 53%, respectively, of the total dry weight consumed forDelesseriaandLaminariadiets) and highest from the seaweeds giving moderate growth (71–75% forUlva, HeterosiphoniaandCryptopleuradiets). ForPlocamiumandEnteromorphadiets the values were 59 and 65%, respectively. Carbohydrate materials were found to constitute 42–75% of the total dry weight of food material absorbed byAplysiaon all the algal diets, and represented the major portion of each. The efficiency of conversion of absorbed food matter into tissues was highest on the algae giving the poorest over-all growth (73% forDelesseriaand 40% forLaminaria). For the other seaweed diets the efficiencies decreased in direct relation to the decrease in the value of each for growth ofAplysia(from 35% forPlocamiumto 15 % forCryptopleura).The same amino acids were found in each food.