Purpleback Flying Squid

## About

A purpleback flying squid.

The purpleback flying squid ***(Sthenoteuthis oualaniensis)*** is a species of squid native to the Indo-Pacific. They possess ten tentacles in total, with two being longer than the others and being used for feeding purposes. Due to highly complex population structures, the purpleback flying squid can be separated into five morphological forms, three major ones and two minor ones. The forms include; a giant form, two medium forms possessing a double and single lateral axis on the gladius respectively, a dwarfed form and a small form which matures earlier than the others. Out of these five groups, the medium squid are the most common and widespread. The medium form is also known for its purplish-blue to navy dorsal photophore patches across its head and mantle, giving the species the name and facilitating bioluminescence. Sexual dimorphism is exhibited, with males reaching a mantle length of 120-150mm and females reaching a mantle length of 190-250mm on average. Encyclopedia of Life claims that individuals can reach up to 650mm however, this is likely in references to a very large medium form individual. Some giant individuals have even been said to be "human-sized", measuring 2m (6ft).

## Diet

Purpleback flying squid forage at night, coming to the water's surface in shallower areas in order to feed. Young squid (paralarva) feed on copepods, amphipods and other species of mesozooplankton and will grow to eat euphausiids, chaetognaths and micronekton fish in addition to their paralarval diet. Once a squid grows to its full length, it will begin consuming larger fish species and even other purpleback squid. When foraging, purpleback squid can congregate in schools of up to 800 individuals and may group with similarly sized Humboldt and neon flying squids ***(Dosidicus gigas)*** and ***(Ommastrephes bartramii)***.

## Conservation Status

The IUCN lists that fishing practices may threaten this species. This is evident in Okinawa, Japan and Taiwan where the species is harvested to be used as bait. The squid are also eaten by people, though their meat is said to be poor in quality. The purpleback flying squid is classed as a species of least concern and the IUCN page for the squid likely requires reevaluation.

## Range and Population

A widely spread species, the purpleback flying squid occurs throughout the Indo-Pacific at depths of up to 600m (1,969ft) below the surface. The species is most highly concentrated in November-January in the Arabian sea.

## Behaviour

The purpleback flying squid is an enigmatic species and its behaviours have not been well-researched.

### Relationship with Humans

The purpleback flying squid is caught in fisheries in Okinawa, Japan and Taiwan to be used as bait and meat.

## In Captivity

No purpleback flying squid exist in captivity.

## Sources

* IUCN Red List of Threatened Species - https://www.iucnredlist.org/species/163152/977501
* Sthenoteuthis oualaniensis | Wikipedia - https://en.wikipedia.org/wiki/Sthenoteuthis\_oualaniensis
* Purpleback Flying Squid | Australian Museum - https://australian.museum/learn/animals/molluscs/purpleback-flying-squid-sthenoteuthis-oualaniensis-lesson-1830/
* Giant purpleblack flying squid photobombs crew investigating shipwreck | Live Science - https://www.livescience.com/purpleback-flying-squid-red-sea
* Purpleback Flying Squid | Encyclopedia of Life - https://eol.org/pages/492079