Techniques for Estimating the Age and Growth of Molluscs: Cephalopoda

Global abundances and commercial fisheries of cephalopods have increased over recent decades, creating a need for effective fishery management. This management is often focused on the ability to ascertain the age structure of key populations. There are several main techniques for age and growth rate determination in cephalopods. Because of biological differences between species groups, not all techniques are applicable for every species. This review outlines the use of five main ageregistering structures (statoliths, gladii, beaks, stylets, and eye lenses) along with one chemical aging technique (lipofuscin) and their application to cephalopod species groups.En prensa1,04

Egg size and fecundity in females of the subfamilies Todaropsinae and Todarodinae (Cephalopoda: Ommastrephidae)

Size of ripe eggs and potential fecundity are described in the squid of the subfamilies Todaropsinae and Todarodinae (Oegopsida: Ommastrephidae)— Todaropsis eblanae from West Africa, Todarodes angolensis from Namibia, Todarodes sagittatus from north-west Africa and the Mediterranean Sea, Todarodes sp. from the south-east Pacific, Nototodarus hawaiiensis from the south-east Pacific and West Indian Ocean and Martialia hyadesi from the south-west Atlantic. Females of both subfamilies are characterized by a wide range of ripe egg size (0.7–2.4 mm) and low and medium values of potential fecundity (20,000–2,500,000)

The biflagellate speratozoa of the squid genus Illex (Cephalopoda, Ommastrephidae): morphology, activity and concentraton in spermatophores

The typical biflagellate spermatozoa were found in all three species of the squid genus Illex, the most primitive genus in the family Ommastrphidae. This is the first finding of that phenomenon in Mollusca. Spermatozoa possess a slightly curved nucleus about 5.5 μm with tiny spheric acrosome, spur-like middle part and two flagella about 50 μm long. Keeping of spermatozoa in open air until destruction, in both sea and fresh water, and in pure alcohol showed a surprising stability of the nucleus shape. Spermatozoa with spheric nucleus habe been found in some preserved samples. This was probably an artifact of preservation, caused by the occasional presence of some unknown admixture in formalin solution which provoked a loss of osmotic stability. The spermatozoon velocity was 130-140 μm/sec which is similar to the maximum value registered in animals. The concentration of spermatozoa in spermatophores was 10.8-17.5 mln/mm³. The effective production of gametes packed in spermatophores was 50-100 billion (100-200 mln/g) in l. argentinus with mantle length (ML) 250-270mm

Cephalopods of the Benguela Current off Namibia: new additions and considerations on the genus Lycoteuthis

The present study contributes new information on the cephalopods off Namibia, contains the first record of Ornithoteuthis volatilis (Sasaki, 1915) in the Atlantic, and adds records of six species in the Benguela Current and three species in Namibian waters. The presence of certain species seldom encountered in the Benguela Current has been confirmed. A compilation of the cephalopod fauna off Namibia had also been included, listing 65 species. Additional morphological data on Stoloteuthis leucoptera, Lycoteuthis lorigera, Architeuthis sp., Pholidoteuthis boschmai, Ornithoteuthis volatilis, Eledone nigra, and Graneledone sp. have been provided. The status of the genus Lycoteuthis has been reviewed in the light of the first collection of Lycoteuthis lorigera (Steenstrup, 1875) males in the Atlantic, and Lycoteuthis diadema (Chun, 1900) has been considered to be a synonym for Lycoteuthis loriger