Abstract

Tissue distribution of ascorbic acid has been determined in phocid and otariid seals and in three species of odontocetes. In all species adrenals and liver contain high concentrations of the vitamin; cetaceans, uniquely, have considerable amounts in the epidermis.

The vitamin is synthesized in the liver of pinnipeds, and to a lesser extent in cetaceans. Vitamin deprivation studies on phocid seals and cetaceans show that daily supplements of vitamin C influence blood levels, but that long term total deprivation has no obvious adverse effects. Fish normally fed to captive marine mammals contain approximately 2 mg of ascorbate per 100 mg of flesh, even after relatively long periods of storage (>6 mo.); viscera contains approximately twice the concentration.

Notes

Vitamin C is a sugar derivative and a reducing agent. It is involved in proline and tyrosine synthesis and thus is an important factor influencing the formation of collagen.

The epidermis of cetaceans contains vitamin C but the pinniped epidermis does not. Levels of vitamin C are high only in metabolically active organs which require an antioxidant.

Higher vertebrates synthesize vitamin C in the liver whereas lower vertebrates synthesize the vitamin in the kidney.

Differing levels of vitamin C were fed in the diet and excretion of the vitamin monitored. With 15 mg ascorbate or less per day in the diet, the vitamin was not wasted. Any more vitamin C than this in the diet was excreted and thus wasted.

Pinnipeds do not need a vitamin C supplement. They receive it in their diet and also synthesize the vitamin. Larger animals such as killer whales have lower metabolic rates so they don't need that many more vitamins than do smaller animals such as the seal.

The results of this study show that pinnipeds synthesize vitamin C and that cetaceans may possibly do so as well.