Ontogenetic changes in the chemical composition of biomass were studied in the laboratory during the abbreviated larval and early juvenile development in the caridean shrimp Campylonotus vagans from the subantarctic Beagle Channel, Argentina. At 7 ±0.5 °C, development from hatching to metamorphosis took about 49 days. The larvae started feeding on Artemia sp. nauplii immediately after hatching, although larval resistance to starvation was high (average: 18 d, maximum 29 d). Dry mass (W), carbon (C), nitrogen (N) and hydrogen (H) contents increased about a four-fold from hatching to metamorphosis, while the C:N mass ratio which increased from about 3.7 to 4.3. The dominating fatty acids were 16:0, 16:1(n-7), 18:0, 18:1(n-9), 18:3(n-3), 18:1(n-7), 20:5(n-3). Except for the latter, these resulted mainly from food uptake (Artemia sp. nauplii). Fatty alcohols detected (14:OA, 16:OA, 18:0A) and wax esters played a negligible role as energy sources. The protein and total lipid contents increased gradually from hatching to the first juvenile stage, the former from 190 to 640 µg/individual, the latter from about 37 to 95 µg/individual. The lipid mass fraction was low throughout larval development (3 to 9 % of W), while the protein content was much higher and almost constant (30-40 % of W). The losses of C, H, and N (all larval stages combined) accounted for only 7, 1, and 1 % of the initial values at hatching; by contrast, 37 % of initial W was lost. Partially food-independent (endotrophic) larval development is discussed as an adaptation to scarcity of food in high latitudes, while the abbreviated planktotrophic larval development appears to be synchronised with seasonal peaks in primary production, allowing for an optimal resource exploitation in a food-limited environment.