Born With Bristles: New Insights on the Kölliker’s Organs of Octopus Skin

The entire skin surface of octopus embryos, hatchlings and juveniles bears scattered tufts tiny chitinous setae within small pockets, from which they can be everted retracted. Known as Kölliker’s organs (KO), disappear before the subadult stage. function these structures during early life is unknown, despite having been first described nearly two centuries ago. To investigate further, general trends in size KO distribution density were analyzed 17 octopod species all oceans, representing holobenthic, holopelagic meropelagic modes life. fairly constant across species, unrelated to mode or hatchling size. similar on ventral dorsal body surfaces, but smaller tend have a higher aboral arms. Analysis series post-hatching Octopus vulgaris shows throughout ontogeny; it therefore consistent structure planktonic benthic juvenile. New are generated arm tips period initial lives juveniles. Their density, both mantle arms, gradually decreases grows. In older juveniles, degrades, losing its base follicle becomes exposed circular stump muscle. It estimated that fully increase area by around two-thirds compared when This modular mechanism extension roughness probably influences flow-related forces such drag propulsion moving young while with relatively large area. addition, arms their birefringent properties suggest role camouflage. Further research needed test hypotheses live animals.