As the first octocoral’s publication by John Ellis in 1755, my interaction with octocorals started with a collection made in collaboration with fishermen on Faial island, Azores. Back in 2007 I wished to understand the impact of fishing on corals inhabiting the deep sea of the Azores. I soon realized that in order to estimate our impact in such a vast area, we need to know what is there in the first place.
From all the major coral groups, the gorgonians were the ones that caught my attention with their diversity, beauty and architectural sophistication. Have you ever looked at these animals under a microscope? If not, I can assure you, you may be struck with amazement at a single glance. Octocorals are among nature’s foremost engineers! In a union of soft tissue with calcareous structures, they stretch and compress in line with the oceanic currents – much like a musician plays an accordion to the pace of the music. Their polyps are hydrostatic systems, with eight mesenteries in the inner part of a hollow body, which hold the eight tentacles, give support and shape to the body providing control of its movements. Bridges among polyps are called coenenchyma, where a system of channels links the polyps. The coenenchyma represents the main structural part of the octocoral body being more voluminous than all octocoral polyps together, in most of the known species. Utmost sophistication and complexity relies on their skeleton: is it an inner or an outer skeleton? Layers of bricks, the sclerites, can be found inside or outside the coral body according to taxa. These bricks are truly diverse in different parts of the body and from species to species. Sclerites control the order of the movements of the thin-walled body under the internal hydraulic pressure and the contraction of the muscles. Diverse shapes of sclerites are arranged to give structure to the octocoral in a major class of architecture. By decreasing the magnification on a microscope, you see the colonies of octocorals, which can form spirals, fans, finger structures, bush structures, etc. Zoom out once again and you will be looking at corals gardens, underwater cities built by their colonies, where fish and many marine invertebrates live, reproduce, hide and eat.
All this amazement and knowledge was inexplicably caught only by a few people. The 20th century began with the main revisions on octocorals made in the NW Atlantic by Dr. Elizabeth Deichmann and in the NE Atlantic Ocean by Prof. John Arthur Thomson. A gap in taxonomic studies followed until the 1950’s when Dr. Frederick Bayer fell in love with these animals in the NW Atlantic Ocean. He became the leading authority of Octocorals and introduced the first published description of an octocoral species using scanning electron micrographs of their sclerites. Dr. Stephen Cairns followed his steps by studying the gorgonians of the family Primnoidae. At the same time, in Europe, Dr. Manfred Grasshoff revised the most common families of gorgonians of the NE Atlantic until the beginning of the 21st Century, becoming the leading expert of this side of the basin. Despite some sporadic publications on specific genus or species, no one followed in his footsteps and a void was left for the upcoming deep-sea exploration era.
It is incomprehensible to me that such diverse and beautiful animals are not attracting more scientists into the field of taxonomy. Despite the common taxonomic impediment going on for many taxonomic groups, there is still a good number of experts working on sponges, bryozoans and hydrozoans, to name a few. Yet, the passion and knowledge of octocorals is now in the hands of retired taxonomists. This gap in expertise begs the question: how can we understand and protect what we do not know? We should not be making conservation choices based on incomplete knowledge.
With this in mind, I decided to follow their leads and continue the taxonomic work that has major importance for all the biological sciences that follow. My PhD project investigates the biodiversity of gorgonians of the family Plexauridae in the NE Atlantic Ocean, following on from the work of Dr Manfred Grasshoff, who revised the previously named Paramuriceidae in 1977. For a decade I have read, identified samples and constructed maps based in his papers. Later, I decided to use his collection at Senckenberg Museum as a reference database for my work. But I would not escape reaching him to learn and share our passion for octocoral’s taxonomy. Thanks to a Network Senckenberg grant, the last two weeks were spent in Frankfurt representing a historical moment for my career in taxonomy.
I finally met Dr. Grasshoff and we spoke about the old times of the field, the octocoral species, the construction of animals, the evolution based in morphological characters and the techniques and tricks which enable a better performance in this research topic. Dr. Grasshoff thinks their skeleton is the most complex of the animal Kingdom and he taught me all about polyps’ anatomy and sclerites function. In Frankfurt, I had access to a specimen of the species first described by Dr Grasshoff, and realised that the Azorean species, previously thought to be the same as the one described by Dr Grasshoff, is probably not. Yet, most importantly, I discovered that half a century of age difference between us has no meaning when we look at octocorals in the same way.
Íris Sampaio is a PhD Candidate to Ocean Sciences, Marine Ecology at MARE & DOP, University of the Azores and Senckenberg am Meer, Wilhelmshaven supervised by Dr. Marina Carreiro-Silva, Prof. Dr. André Freiwald and Dr. Gui Menezes. She travelled to Senckenberg Museum funded by Forschungs-Alumni-Netzwerk Senckenberg (FANS) with the support of the Research Alumni Strategies-program of the Alexander von Humboldt Foundation.
Hand-coloured octocoral prints by Johann Esper 1791