The spindle-shaped body of the firefly squid is covered in bioluminescent organs called photophores that emit a blue-green light. In the case of these shimmering cephalopods, they utilise the adaptation to attract prey such as small fish down in the gloomy mesopelagic zone.
But they also demonstrate another evolutionary phenomenon. Counter-illumination, a form of camouflage in which they light up in varying intensities to match the ambient light around them. For example, they glow brighter as they ascend to shallower waters at night. The colour they emit matches the faint glow of moonlight from the surface, meaning they can blend in with their surroundings whether it is dark or light, and hide themselves from predators. In much of the open ocean there is no concealment, so animals must adapt to be able to hide in the wide open. This unique skill is helped by the fact that firefly squid are the only cephalopods to see in colour, so they are able to distinguish between the ambient light and their own bioluminescence.
Firefly squid gather at the surface in large numbers from March until May during their spawning season. Here at Toyama Bay in Japan, they bathe the beaches in an eerie blue glow, lighting up particularly bright in order to attract a mate.
However, not all bioluminescent creatures are able to produce their own light themselves.
00:00 – Introduction
00:41 – What is Bioluminescence?
02:01 – Bioluminescent Creatures
02:42 – Bioluminescence in the Firefly Squid
03:07 – How Counter-illumination Works
03:54 – Firefly Squid Spawning
04:13 – Symbiotic Bioluminescent Bacteria
04:25 – Bioluminescence in Anglerfish
05:22 – How Bioluminescence Works
05:58 – Bioluminescence in the Green Bomber Worm
06:12 – Why is Bioluminescence Blue?
06:49 – Bioluminescence in the Bloody-Belly Comb Jelly
07:01 – Why do Deep Sea Creatures have Large Eyes?
07:36 – Conclusion
08:02 – The Deep Sea Hub
DEEP SEA HUB: https://naturalworldfacts.com/deep-sea-hub/
#deepsea #wildlife #ocean #vampiresquid #deepseawonders #bioluminescence #marinebiology
Resources:
https://www.nationalgeographic.org/encyclopedia/bioluminescence/
https://pubs.acs.org/doi/10.1021/jacs.6b09119
https://biolum.eemb.ucsb.edu/organism/erenna.html
http://www.seasky.org/deep-sea/firefly-squid.html
Video sources:
– MBARI
– OceanX
– David Attenborough’s Light on Earth
– EVNautilus