Smaller squid make up for their diminutive size, and reduced sexual status, by producing bigger sperm.
They produce the outsized sperm in a bid to thwart the chances of larger male squid rivals impregnating females.
While the smaller males are unable to compete with the larger males, their sperm can.
Scientists based in Japan made the discovery studying spear squid, otherwise known as Bleeker's squid (Loligo bleekeri).
Details are published in the journal BMC Evolutionary Biology.
Male spear squid employ one of two tactics when seeking to pair with a mate.
Larger males, known as "consorts", court females by flashing bright displays of colour across their bodies.
They compete with other large males and the winner mates with the female, depositing sperm in a package inside her oviduct.
He then guards her until she spawns her eggs.
Smaller males however, employ a different tactic.
These so-called "sneaker" males don't advertise themselves and show few of the behaviours of their larger rivals.
Instead, they wait until a larger male is guarding a female, then rush in head first to copulate with her.
A sneaker male mates in a head-to-head position and deposits his sperm in a different place to the larger males, putting his sperm package on the outside of the female's body just below her mouth.
The timing of this intervention is crucial.
The smaller male dashes in just as the female begins laying her eggs, in the hope that they will pass over his sperm and be fertilised by him rather than the female's original suitor.
The species is unusual in another way however.
These smaller males produce different sperm to the larger males.