Bioluminescence makes comeback

The Daily Herald writes about the Sea&Learn presentation by Sönke Johnsen as follows. Bioluminescence, marine-life optic illusions and camouflage abilities made a comeback this year after their big visual splash in last year’s Sea and Learn Saba season. Saba discovered its night-time marine bioluminescent “string of pearls” phenomenon last year, observed at night as part of a marine species mating dance. That experience secured an already-seduced audience for Sönke Johnsen talk about the peculiar life of jellyfish held at Scout’s Place in Windwardside on October 21. His lecture, titled “Hide and Seek in the Open Sea,” brought captivating imagery of marine life optical illusions.

That same evening, Wageningen University agriculture student Giuseppe “Peppe” Alessandrello also held a presentation on attempts to implement a mushroom cultivation programme on Saba. Titled “More fungus among us?” it raised interest with some participants looking forward to Saba’s experimental mushroom crops within two months. Peppe helped Sea and Learn organisers this year taking their local youth group, “YELP,” on a tour of the Organoponics garden at The Level and discussing with them the benefits of sustainable organic farming and mushrooms in particular.

The evening’s feature presentation belonged to Johnsen, an expert in marine vision and camouflage with experience extending to nocturnal illumination and signalling in terrestrial species. A trained mathematician with an artist’s soul, Johnsen’s work bridges the worlds of artists, theoretical and experimental scientists implementing morphological and behavioural studies of animals’ optical tricks while using deep-sea submersibles.

He talked about marine-life transparency, cryptic coloration, mirrors and counter illumination techniques. The size of some the transparent species presented ranged from some of the tiny, most abundant animals on the planet to some eight-meter-long samples that successfully evade human observation in the absence of special lighting. With regard to coloration and pigmentation techniques, he showed how environmental illumination and light wavelength manipulate perception of colour. Fish skin scales act as shinny vertical mirrors for stealth purposes. In squid, octopus and other animals, these mirrors are animated under neural control, changing what colour is sent back through skin structural changes that allow them to mimic backgrounds. The big challenge with such camouflage is rapid adaptation to background changes. Among the more intriguing marine-life adaptations, some deep-sea fish species developed the counter illumination technique with complex forms of light distribution illusions. Some predator species even developed chemical flashlights to surprise and identify prey. The mesmerising photo-filled presentation led to a battery of questions about how to capture such photography and the techniques used by Johnsen in research.