Doryteuthis (Amerigo) pealeii (Lesueur 1821)

The longfin inshore squid (Doryteuthis pealeii) is a species of squid of the family Loliginidae.

Description

This species of squid is often seen with a reddish hue, but like many types of squid can manipulate its color, varying from a deep red to a soft pink. The dorsal mantle length of some males can reach up to 50 cm, although most squid commercially harvested are smaller than 30 cm long. This species exhibits sexual dimorphism, with most males growing faster and reaching larger sizes than females.

Specimen with tentacles outstretched

The gladius of a longfin inshore squid

Distribution

The longfin inshore squid is found in the North Atlantic, schooling in continental shelf and slope waters from Newfoundland to the Gulf of Venezuela. It is commercially exploited, especially in the range from the Southern Georges Bank to Cape Hatteras. The population makes seasonal migrations that appear to be related to bottom water temperatures; they move offshore during late autumn to overwinter along the edge of the continental shelf and return inshore during the spring and early summer (MAFMC 1998).

Diet

"The diet of the longfin inshore squid changes with size; small immature individuals feed on planktonic organisms while larger individuals feed on crustaceans and small fish. Studies have shown that juveniles feed on euphausiids and arrow worms, while older individuals feed mostly on small crabs, but also on polychaetes and shrimp. Adults feed on fish (clupeids, myctophids) and squid larvae/juveniles, and those larger than 16 cm feed on fish and squid. Fish species preyed on by longfin inshore squid include silver hake, mackerel, herring, menhaden, sand lance, bay anchovy, weakfish, and silversides. Maurer and Bowman (1985) discovered a difference in inshore/offshore diet: in offshore waters in the spring, the diet is composed of crustaceans (mainly euphausiids) and fish; in inshore waters in the fall, the diet is composed almost exclusively of fish; and in offshore waters in the fall, the diet is composed of fish and squid. Cannibalism is observed in individuals larger than 5 cm."^[2]

Predators

Many pelagic and demersal fish species, as well as marine mammals and diving birds, prey upon juvenile and adult longfin inshore squid. Marine mammal predators include longfin pilot whales and common dolphins. Fish predators include striped bass, bluefish, sea bass, mackerel, cod, haddock, pollock, silver hake, red hake, sea raven, spiny dogfish, angel shark, goosefish, dogfish, mako shark, blue marlin and flounder. These squid do have ways of evading predators too. They have a very complex way of swimming called jet propulsion. The fin stroke plus the propulsion creates a very unique way of swimming in the ocean. This can help squid get away from predators more efficiently. ^[3]

Reproduction

The longfin inshore squid spawns year-round and lives for less than one year. "Eggs are demersal. Enclosed in a gelatinous capsule containing up to 200 eggs. Each female lays 20-30 capsules. Fecundity ranges from 950–15,900 eggs per female. Laid in masses made up of hundreds of egg capsules from different females."^[2] Individuals hatched in summer generally grow more rapidly than those hatched in winter due to the warmer temperature of the water. The lifespan of a typical specimen is normally less than one year.

Research

This species is a model organism in neuroscience and it was used by Andrew Huxley and Alan Hodgkin in their studies on axons. Its axon is the largest axon known to science.^[4] They are also used for research on replicating their camouflage abilities due to the chromatophores in their skin, which reflect a different color depending on the angle at which the light is hitting them. A dead longfin can show a colourful display with its chromatophores by connecting its axons to a music player.^[5][6][7]

References

El calamar pálido (Doryteuthis (Amerigo) pealeii) pertenece al orden Myopsida que incluye a calamares neríticos, normalmente de aguas poco profundas. Muchas de las especies son ágiles nadadores, se encuentran en grandes grupos y son pescados para comida y en algunos casos actuales para investigación médica (neurociencia).

Clasificación y descripción

D. pealeii (también Loligo pealeii) pertenece a la clase Cephalopoda de moluscos; al orden de los myopsidos; a la familia de los loliginidos. Esta familia contiene especies de tamaño muy variable, como L. forbesii que tiene una longitud de 90 cm, hasta organismos enanos del género Pickfordiateuthis con masculinos de 14 mm de longitud.^[1]​

El calamar flecha (D. pleii) es de tamaño mediano, alrededor de 50 cm de longitud. Como todos los calamares, posee diez brazos (ocho del mismo tamaño y dos más largos que son utilizados para cazar y sostener la presa). Posee tres corazones, dos de ellos cerca de las branquias (sistema circulatorio cerrado).^[2]​

Distribución

Atlántico oeste, en aguas superiores del talud continental desde Nueva Escocia hasta Venezuela, incluyendo el Golfo de México y el Mar Caribe.

Estado de conservación

Es un recurso pesquero que tiende a ser sobreexplotado y está protegido por periodos de pesca temporales.

La utilización de estos calamares en la medicina radica en la presencia de axones mil veces más grandes que su contraparte humana. Esto ha dado la oportunidad de estudiar las bombas de sodio y potasio con mayor detenimiento, ayudando así entender mejor las enfermedades del corazón, cáncer, enfermedad de Alzheimer y enfermedades del riñón.^[3]​

Referencias

Doryteuthis pealeii

Le calmar totam (Doryteuthis pealeii^[1]) est une espèce de calmar de la famille des ommastrephidés.

Il calamaro atlantico^[1] (Doryteuthis pealeii) è un mollusco cefalopode della famiglia dei Loliginidae^[2].

Organismo modello

Neuroscienze

Questa specie è un organismo modello nelle neuroscienze: è stato utilizzato da Andrew Huxley e Alan Hodgkin nei loro studi sulla conduzione nervosa negli assoni, e viene tuttora utilizzato allo scopo.

Divenne oggetto di ampi studi neurologici a causa del suo "assone gigante" (quasi 1 mm di diametro, circa 1000 volte maggiore di un assone medio di mammifero).

Etologia e citologia

Viene anche utilizzato per studiare la capacità di mimetizzazione causata dai cromatofori presenti nella pelle.

Note

Bibliografia

• (EN) Williams, L. W. 1910. The anatomy of the common squid: Loligo pealii, Lesueur. Leiden, 92 pp.

Doryteuthis pealeii is een inktvissensoort uit de familie van de Loliginidae.^[1] De wetenschappelijke naam van de soort is voor het eerst geldig gepubliceerd in 1821 door Lesueur.