78
J. C. Navarro et al.
bottlenecks remain and are impeding the transition of technology from pilot to fullscale, namely the existing knowledge on cephalopod nutrition. Nutrition is a key
factor for proper growth and survival under captive conditions and mass culture.
This chapter picks up from the last review on this subject, made by Lee (1994).
Firstly, it presents a nutritional approach, which is mostly based on the biochemical
composition of both cephalopods and preys, and finalizes with a metabolic hypothesis, which considers other variables such as enzymes, geographical adaptation and
stress. Due to the low amount of existing information for most cephalopod species,
this chapter mainly focuses on nutritional studies conducted in Sepia officinalis and
Octopus vulgaris, arguably the cephalopod species of greatest commercial interests.
5.2 Proteins
Proteins are the most abundant macronutrient in cephalopods (Zlatanos et al.
2006) and, as stated by Lee (1994), large protein and amino acid contents in the
diet of cephalopods are required for sustaining growth and fulfilling energy demands. According to Lee (1994), cephalopods efficiently absorb, digest and utilize dietary proteins that are further used for locomotion, structural support, energy source, oxygen transport and osmoregulation. Cephalopods display high rates
of protein synthesis and retention, and low rates of protein degradation (Houlihan
et al. 1990; Moltschaniwskyj and Carter 2010). In order to evaluate the dietary
requirements of the common octopus O� vulgaris during the fast-growing stages,
the total and free amino acid (FAA) composition of paralarvae and juveniles was
determined by Villanueva et al. (2004). Similar to the amino acid content found
in the mantle of juveniles of O� vulgaris, S� officinalis and Loligo vulgaris by
Zlatanos et al. (2006), these authors found that glutamate and aspartate were the
most abundant nonessential amino acids (NEAAs) in O� vulgaris paralarvae, with
lysine, leucine and arginine accounting for nearly half of the essential amino acids
(EAAs). Interestingly, arginine was the most abundant FAA in paralarvae, possibly indicating its further use for octopine formation produced during an anaerobic
work (Baldwin et al. 1976; Hochachka et al. 1976, 1983; Storey and Storey 1979;
Storey et al. 1979; Hochachka and Fields 1982) or an active metabolism for energy production and biosynthesis of other amino acids. On the other hand, cephalopods might use proline during oxidative metabolism, either as energy source
or as means for augmenting the Krebs cycle (Hochachka and Fields 1982). Both
arginine and proline are potentially interconvertible through glutamate and ornithine (Mommsen et al. 1982).
In a general way, there is already information on the amino acids of O� vulgaris
prey species, such as for Artemia spp. (Aragão et al. 2004) and crustaceans such as
the spider crab (Andrés et al. 2010), as well as for raw materials used for prepared
diets (Valverde et al. 2013). Cephalopod’s growth is primarily an increase in body
muscle mass by protein synthesis and accretion, and individuals display very high
growth rates (especially at the paralarvae and hatchling stages), which means that
they have a high dietary requirement for amino acids. In addition, these high growth
J. C. Navarro et al.
bottlenecks remain and are impeding the transition of technology from pilot to fullscale, namely the existing knowledge on cephalopod nutrition. Nutrition is a key
factor for proper growth and survival under captive conditions and mass culture.
This chapter picks up from the last review on this subject, made by Lee (1994).
Firstly, it presents a nutritional approach, which is mostly based on the biochemical
composition of both cephalopods and preys, and finalizes with a metabolic hypothesis, which considers other variables such as enzymes, geographical adaptation and
stress. Due to the low amount of existing information for most cephalopod species,
this chapter mainly focuses on nutritional studies conducted in Sepia officinalis and
Octopus vulgaris, arguably the cephalopod species of greatest commercial interests.
5.2 Proteins
Proteins are the most abundant macronutrient in cephalopods (Zlatanos et al.
2006) and, as stated by Lee (1994), large protein and amino acid contents in the
diet of cephalopods are required for sustaining growth and fulfilling energy demands. According to Lee (1994), cephalopods efficiently absorb, digest and utilize dietary proteins that are further used for locomotion, structural support, energy source, oxygen transport and osmoregulation. Cephalopods display high rates
of protein synthesis and retention, and low rates of protein degradation (Houlihan
et al. 1990; Moltschaniwskyj and Carter 2010). In order to evaluate the dietary
requirements of the common octopus O� vulgaris during the fast-growing stages,
the total and free amino acid (FAA) composition of paralarvae and juveniles was
determined by Villanueva et al. (2004). Similar to the amino acid content found
in the mantle of juveniles of O� vulgaris, S� officinalis and Loligo vulgaris by
Zlatanos et al. (2006), these authors found that glutamate and aspartate were the
most abundant nonessential amino acids (NEAAs) in O� vulgaris paralarvae, with
lysine, leucine and arginine accounting for nearly half of the essential amino acids
(EAAs). Interestingly, arginine was the most abundant FAA in paralarvae, possibly indicating its further use for octopine formation produced during an anaerobic
work (Baldwin et al. 1976; Hochachka et al. 1976, 1983; Storey and Storey 1979;
Storey et al. 1979; Hochachka and Fields 1982) or an active metabolism for energy production and biosynthesis of other amino acids. On the other hand, cephalopods might use proline during oxidative metabolism, either as energy source
or as means for augmenting the Krebs cycle (Hochachka and Fields 1982). Both
arginine and proline are potentially interconvertible through glutamate and ornithine (Mommsen et al. 1982).
In a general way, there is already information on the amino acids of O� vulgaris
prey species, such as for Artemia spp. (Aragão et al. 2004) and crustaceans such as
the spider crab (Andrés et al. 2010), as well as for raw materials used for prepared
diets (Valverde et al. 2013). Cephalopod’s growth is primarily an increase in body
muscle mass by protein synthesis and accretion, and individuals display very high
growth rates (especially at the paralarvae and hatchling stages), which means that
they have a high dietary requirement for amino acids. In addition, these high growth