88
J. C. Navarro et al.
lism that maximizes ATP yield per unit of consumed oxygen due to the lack of an
intracellular myoglobin analogue and the exclusive localization of mitochondria in
interfibrillar zones (Hochachka 1994; Ballantyne 2004). CH are catabolized rapidly
following ingestion, and are not used during fasting, but mobilized for locomotor activity (O’Dor et al. 1984). According to Hochachka and Fields (1982) and Storey and
Storey (1978), glucose metabolism may be coupled to that of proline through glucose
conversion to pyruvate, which is oxidized in the Krebs cycle, and proline simultaneously augments the cycle intermediates. These first authors still add that glutamate,
proline and most probably arginine can be used directly as gluconeogenic precursors.
5.9 Conclusions
Proteins are the most abundant macronutrient in cephalopods, and large protein and
amino acid contents in the diet are required for sustaining growth and eventually
fulfilling energy demands. Although low in quantitative terms, lipids are essential in
cephalopod nutrition, with long-chain PUFA playing a pivotal role, since the enzymatic machinery unveiled through molecular research points at their inability in the
synthesis of these important nutrients. Therefore, the effect of dietary protein/lipid
ratios on amino acid absorption efficiency and metabolism needs to be researched.
Cephalopods also require an adequate provision of antioxidants like pro-vitamin
A and carotenoids, since the importance of vitamins in photoreception, growth and
development must not be neglected. It is generally accepted that cephalopods do not
have a specific requirements for dietary CH, but it has been reported that they are
able to rapidly catabolize dietary CH to account for energy demands in explosive
activities such as prey capture and fleeing from predators, and the existence of a
CH metabolism has been established. However, the CH theory presented in this
chapter needs to be proven. Finally, it is accepted that octopuses and cuttlefish, as
carnivorous species, meet the majority of their elemental requirements from the
diet, although direct uptake from the seawater has also been shown to occur through
an ion balance mechanism regulated by the digestive gland appendages.
Methods for the determination of possible metabolic pathways have been developed for fish larvae (Conceição et al. 2003; Morais et al. 2004) and these may
be adapted for the study of metabolism in cephalopods. Additionally, the use of
systems biology modelling to cephalopod nutrition, similar to that published by
Hormiga et al. (2010), might help on a faster progress towards our understanding of
cephalopods’ physiology and nutrition.
References
Almansa E, Domingues P, Sykes A et al (2006) The effects of feeding with shrimp or fish fry on
growth and mantle lipid composition of juvenile and adult cuttlefish ( Sepia officinalis). Aquaculture 256:403–413
J. C. Navarro et al.
lism that maximizes ATP yield per unit of consumed oxygen due to the lack of an
intracellular myoglobin analogue and the exclusive localization of mitochondria in
interfibrillar zones (Hochachka 1994; Ballantyne 2004). CH are catabolized rapidly
following ingestion, and are not used during fasting, but mobilized for locomotor activity (O’Dor et al. 1984). According to Hochachka and Fields (1982) and Storey and
Storey (1978), glucose metabolism may be coupled to that of proline through glucose
conversion to pyruvate, which is oxidized in the Krebs cycle, and proline simultaneously augments the cycle intermediates. These first authors still add that glutamate,
proline and most probably arginine can be used directly as gluconeogenic precursors.
5.9 Conclusions
Proteins are the most abundant macronutrient in cephalopods, and large protein and
amino acid contents in the diet are required for sustaining growth and eventually
fulfilling energy demands. Although low in quantitative terms, lipids are essential in
cephalopod nutrition, with long-chain PUFA playing a pivotal role, since the enzymatic machinery unveiled through molecular research points at their inability in the
synthesis of these important nutrients. Therefore, the effect of dietary protein/lipid
ratios on amino acid absorption efficiency and metabolism needs to be researched.
Cephalopods also require an adequate provision of antioxidants like pro-vitamin
A and carotenoids, since the importance of vitamins in photoreception, growth and
development must not be neglected. It is generally accepted that cephalopods do not
have a specific requirements for dietary CH, but it has been reported that they are
able to rapidly catabolize dietary CH to account for energy demands in explosive
activities such as prey capture and fleeing from predators, and the existence of a
CH metabolism has been established. However, the CH theory presented in this
chapter needs to be proven. Finally, it is accepted that octopuses and cuttlefish, as
carnivorous species, meet the majority of their elemental requirements from the
diet, although direct uptake from the seawater has also been shown to occur through
an ion balance mechanism regulated by the digestive gland appendages.
Methods for the determination of possible metabolic pathways have been developed for fish larvae (Conceição et al. 2003; Morais et al. 2004) and these may
be adapted for the study of metabolism in cephalopods. Additionally, the use of
systems biology modelling to cephalopod nutrition, similar to that published by
Hormiga et al. (2010), might help on a faster progress towards our understanding of
cephalopods’ physiology and nutrition.
References
Almansa E, Domingues P, Sykes A et al (2006) The effects of feeding with shrimp or fish fry on
growth and mantle lipid composition of juvenile and adult cuttlefish ( Sepia officinalis). Aquaculture 256:403–413