The year of the Blue Ringed Octopus

What has nine brains and some of the most potent venom in the world? The incredible Blue Ringed Octopus.

A favourite dive of many of our students, interns and instructors is when we head of into the unexplored soft-sediment areas around our island in search of new and exciting marine life. Whilst most divers are spending their time exploring the reef, we head off into deeper waters on the hunt for some of Koh Tao’s most elusive and unique marine life.

Off the reef in the soft sediment is where we begin our search. This environment affectionately known as the “muck” habitat is home to a myriad of species and creatures that most divers don’t get the opportunity to see. Hidden amongst sea pens, soft corals, algae and tube anemones is a world of biodiversity waiting to be discovered.

Our ventures into the muck in 2017 brought with it the rarely observed seahorses, nudibranchs previously unobserved on Koh Tao of the Gulf, synaptid sea cucumbers, prickly porcupine puffers, the most venomous snake on the planet – the banded sea kraits, elusive porcelain crabs, and so much more.

A few of the interesting animals from our muck dives: Nudibranchs, Cowries, and Porcelin Crabs

But one of the most exciting creatures that kept appearing, which quickly became the highlight of many of our muck dives, was the incredibly small but deadly, Blue Ringed Octopus.

Blue ringed octopus

This species is very rare in the Gulf of Thailand, as can be attested by long-term divers and local researchers. In previous years, the NHRCP had only recorded 2 sightings of this elusive creature, but in 2017 a new record was reached with more than 20 individual observations during our muck dives. In one instance we were also fortunate enough to find a female carrying her eggs!

The Blue Ringed Octopus is a small species, with a head about the size of a golf ball and a body reaching up to 20cm in length. However, these interesting cephalopods pack a potent venom - placing them amongst the most venomous animals on the planet. The venom, which is administered through their small beaks, contains tetrodotoxin, a potent neurotoxin in the same order of toxins that can be found in pufferfish and moon snails.

Their name comes from the blue rings that are visible when the animal becomes provoked or wishes to warn anything that comes too close. It’s a common misconception that these blue rings come from the octopuses chromatophores, but these pigmented cells generally only come in browns, blacks, oranges, reds and yellows. The vibrant blue rings actually come from specialized cells underneath these layered chromatophores, known as iridophores. These specialized cells are made of chitinous and protienatious platelets that reflect light, producing the vibrant blues that these beautiful octopods derive their name from. Much like chromatophores, these blue rings are thought to be another avenue for communication amongst these mysterious, intelligent invertebrates.

These amazing animals, along with other species of octopus have been found hiding in and amongst discarded bottles and holes that had been vacated by previous tenants, as well as underneath old bivalve shells.

We can’t wait to see what new and incredible species these muck dives will yield in 2018!