A Highly Stealthy Critter – The Bobtail Squid

Another interesting marine critter that is of great interest not only to divers and underwater photographers but including scientists is this little marine critter that looks like the cartoon character “Dumbo the Flying Elephant”, the Bobtail Squid. But this critter is¬†definitely not dumb as it is able to make use of its symbiotic relationship with a bacteria to break its silhouette and mimic moonlight and varies it brightness to match. This uncanny behaviour of mimicking moonlight to remove its shadows and protect it from bottom dwelling predators waiting to hunt it while the Bobtail is hovering and hunting its prey at night is another amazing development of evolution.

Light emitting characteristic of Bobtail Squid
Bobtail Squid has a symbiotic relationship with a bioluminescent bacteria, Aliivibrio fisheri, which lives in the light emitting organ in the mantle of the squid. Notice the glow around its mantle. Has a halo effect.

The Bobtail Squid belongs to Sepiadariidae family of squid and are closely related to the Cuttlefish. It is also called the “dumpling squid” or “stubby squid”. Generally quite small about 1cm to 4 cm. It can swim by finning using its round fins next to its mantle or by jet propulsion. It is distributed from Indian Ocean to Pacific and Atlantic Ocean. Found in coastal waters in sandy and muddy habitats.

This Bobtail Squid is nocturnal in nature and spend the day buried in the sand. Only to emerge at night to hunt for food using its stealth features to help it hunt and protect it from its predators.

The Bobtail Squid unique symbiotic relationship with a bioluminescent bacteria, Aliivibrio fisheri, that lives in the “light organ” in the mantle of the squid helps the Bobtail squid to mimic the moonlight and vary its intensity to match. This light emitting and varying characteristic protects the squid from casting a dark shadow as it hovers over the ocean bottom and thus prevent it from being detected by predators dwelling below.

This Bobtail Squid was found about 10m depth at Jahir dive point, Lembeh Straits in a night dive. It was scurrying to bury itself in the sand when approached. It became more settled eventually and I was able to take a few more images of this beautiful critter before it decided to move away into the darkness with its mantle glowing.

Using its tentacles to shift the sand to hide in it.
Bobtail Squid scurrying to bury itself in the sand when approached. Notice the beautiful purplish blue glow around its mantle.

Night dive in Lembeh is full of exciting finds and this is one of them. I am in awe when I dive at Lembeh whether in a day or night dive as you often discover new and different critters around you waiting for you discover and learn more about them.

What amazing dive sites at Lembeh and the dive guides are there to show you these amazing critters.

Enjoy your dives as much as I enjoy mine.

Dive safe always !

 

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