The life cycle of Teuthowenia megalops has not been extensively observed.
From the recorded depths of captured adult specimens, it is assumed that mating and spawning happens in the deep midwaters, at depths greater than 1,000 m (3,300 ft).
At these depths, the waters are quite dark.
The bioluminescent photophores as well as pheromones released into the water may help the squid find mates.
Once the males find the females, they harpoon them with spermatophores directly on the mantles.
The spermatophores penetrate into the mantle cavity of the female where they discharge sperm.
The females spawn only once before dying.
No eggs of the species have ever been collected from the wild, but examination of collected specimens of gravid females puts the estimated fecundity at 70,000 to 80,000 eggs per individual.

Upon hatching, the paralarvae gradually float or swim towards shallower waters.
The paralarvae differ from adults in having stouter barrel-shaped bodies with a blunt posterior end.
The fins are very small and unfused.
The funnel is broad and large and lack tubercles on the funnel-mantle fusion, unlike in adults.
The eyes are small with developing photophores visible.
They are slightly flattened dorsoventrally and mounted on short thick stalks.
The arms are mere stubs, with lengths of 0.8 to 1.4 mm (0.031 to 0.055 in) when they reach mantle lengths of 8 to 9 mm (0.31 to 0.35 in).
In contrast, the tentacles are very long and thick but without an expanded club.
Four rows of suckers extend from the club to almost the base of the stalks.
The mantle, head, arms, and tentacles are covered with relatively large widely spaced chromatophores.

The paralarvae develop the characteristic tubercle at the funnel-mantle fusion once they reach the mantle lengths between 30 and 60 mm (1.2 and 2.4 in).
They enter the subadult stage once the eyes lose their stalks, becoming sessile, at sizes between 75 and 95 mm (3.0 and 3.7 in).
The arms and arm suckers enlarge rapidly and males begin to develop their arm modifications (with the exception of the modifications of the first arm pair, which occurs near maturity).
At this stage they may already have moved back to depths exceeding 1,000 m (3,300 ft).

The entire lifespan of Teuthowenia megalops is estimated to be two to three years.
The life cycle of Teuthowenia megalops has not been extensively observed. From the recorded depths of captured adult specimens, it is assumed that mating and spawning happens in the deep midwaters, at depths greater than 1,000 m (3,300 ft). At these depths, the waters are quite dark. The bioluminescent photophores as well as pheromones released into the water may help the squid find mates. Once the males find the females, they harpoon them with spermatophores directly on the mantles. The spermatophores penetrate into the mantle cavity of the female where they discharge sperm. The females spawn only once before dying. No eggs of the species have ever been collected from the wild, but examination of collected specimens of gravid females puts the estimated fecundity at 70,000 to 80,000 eggs per individual.
Upon hatching, the paralarvae gradually float or swim towards shallower waters. The paralarvae differ from adults in having stouter barrel-shaped bodies with a blunt posterior end. The fins are very small and unfused. The funnel is broad and large and lack tubercles on the funnel-mantle fusion, unlike in adults. The eyes are small with developing photophores visible. They are slightly flattened dorsoventrally and mounted on short thick stalks. The arms are mere stubs, with lengths of 0.8 to 1.4 mm (0.031 to 0.055 in) when they reach mantle lengths of 8 to 9 mm (0.31 to 0.35 in). In contrast, the tentacles are very long and thick but without an expanded club. Four rows of suckers extend from the club to almost the base of the stalks. The mantle, head, arms, and tentacles are covered with relatively large widely spaced chromatophores.
The paralarvae develop the characteristic tubercle at the funnel-mantle fusion once they reach the mantle lengths between 30 and 60 mm (1.2 and 2.4 in). They enter the subadult stage once the eyes lose their stalks, becoming sessile, at sizes between 75 and 95 mm (3.0 and 3.7 in). The arms and arm suckers enlarge rapidly and males begin to develop their arm modifications (with the exception of the modifications of the first arm pair, which occurs near maturity). At this stage they may already have moved back to depths exceeding 1,000 m (3,300 ft).
The entire lifespan of Teuthowenia megalops is estimated to be two to three years.
Teuthowenia megalops