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Nudibranchs and the fabulous Spanish Dancer (Hexabranchus sanguineus)



Every good Dive Master/photographer has a problem. They must look after their clients while still taking pictures. They have no time to vary the depth of focus, no time to change camera settings; their dive clients must always come first. Colin Ogden of Amoray Diving at Sodwana Bay solved the problem by shooting nudibranchs, and his study of these amazing creatures has become a passion. I spent a spellbinding evening with him learning about them.

Nudibranchs come in brilliant colours, with fabulous markings, and they can vary in size from 1mm to 600mm. They are primarily carnivores and will eat hydroids and other species of nudibranchs but most of them feed on sponges; all of which are animals. A few will eat algae or seaweed. They feed where food is available so they frequent areas where coral growth is limited; even the cold Northern European waters harbour these colourful sea slugs and nudibranch hunting has become a global passion.

Nudibranch means exposed gills. Hexabranchus, for example, has six sets of exposed gills. All but two nudibranchs are called by their Latin names. The scientific community frowns on them being given common names so the study of these creatures is not for the faint-hearted.

Most of them breath using the exposed bunches of gills on their backs, and their sensual organs are contained in a pair of rhinophores, on the front of their heads. These look like horns. All are hermaphrodite, with both male and female sex organs, which are always on the right hand side, below the neck. These can be expelled to accommodate a large meal, and then re-ingested. All of them are poisonous to fish, and a single nudibranch can kill an entire aquarium full of fish if it becomes stressed and lets off a toxin. This occasionally benefits the palatable flatworm. He sometimes mimics the shape and rhinophores of the poisonous nudibranch, escaping predators and protecting himself.







There is even a species that farms algae in its gills.  It is long and thin and has many sets of gills or cerata which he uses to collect algae. You will sometimes find it spread out along the top of the reef on a sunny day, cerata exposed to catch the sun so the algae will grow faster.

The spectacular Spanish Dancer (Hexabranchus sanguineus) is one of the very few nudibranchs that goes by its common name. They grow up to 600mm long, so are clearly identifiable. “They are nocturnal animals in our waters, so we rarely spot them in Sodwana Bay. However, we found two on the point of mating on Seven Mile in broad daylight. They lined up neck to neck, and then they exchanged sperm, fertilising each other. After five or six days each lays a long egg ribbon in a continuous circle, and you can see these on the reef looking like soft rosettes.







They are normally pink, reddish or orange. These ribbons are preyed upon by other nudibranchs of the Favourinus family and the survivors hatch into tiny nudibranchs that look nothing like their imposing parents.

Other species lay egg ribbons that hatch into tiny veligers, which are a larval stage, and they can float around in the ocean, following currents for months on end. When they sense that there is a food source, they will descend onto the reef and metamorphose into small nudibranchs. The study of these creatures is still in its infancy, although some were described as early as the 1700s, but they are fascinating creatures, and there are still many unnamed and quite rare species in our waters. Once you know what you are looking for, you can find them almost everywhere.

Words: Jill Holloway

Pictures and technical data: Colin Ogden, Amoray Diving

Copyright Ocean Spirit 2017 –

Jill Holloway lives in Mauritius and at Sodwana Bay Isimangaliso Wetland Park in South Africa. A PADI qualified Nitrox diver with over 1,500 dives, she is a passionate observer and preserver of the marine environment, and has a database of over 35,000 fish pics and hundreds of Gopro videos on fish behaviour, which she shares with her readers.


New academic study to confirm rehabilitative benefits of Scuba Diving



A new study into Scuba Diving Rehabilitation Charity Deptherapy’s approach to supporting Armed Forces veterans with psychological injuries such as Post-traumatic Stress Disorder (PTSD) through the medium of scuba diving has been carried out by Petra Walker in conjunction with Hanna Kampman of the Posttraumatic Growth Research Unit at the University of East London.

This study, which used Interpretive Phenomenological Analysis (IPA), demonstrates that scuba diving has rehabilitation benefits beyond those found in other forms of sporting rehabilitation exercise.

IPA is a qualitative methodology that examines the experiences of participants and has been used in previous studies of Posttraumatic Growth (PTG) in para-athletes.

Petra is an experienced diver herself and was exploring the wellbeing aspects of scuba diving as part of her Masters in Applied Positive Psychology and Coaching Psychology when she came across a previous study on Deptherapy. Past studies have mainly focused on the medical aspects of diving, so the opportunity to examine the mental health side of rehabilitative scuba diving was impossible to ignore.

The full study is currently embargoed until it is published at a future date in an academic journal, but it follows similar academic research into the work of Deptherapy by the University of Sheffield Medical School (2018) and the University of Nottingham (2019).

Richard Cullen, Chairman of Deptherapy commented: “This evidence-based study demonstrates yet again the value of scuba diving and, in particular, the support provided by Deptherapy to severely traumatised people within the Armed Forces community. We await the publication of the detailed findings which we anticipate will be of considerable interest to all organisations who seek to assist in the rehabilitation of veterans through sporting activity, as well as the Scuba Diving world.”

Team Deptherapy returned to the UK last week from their first training expedition since the start of the COVID-19 Pandemic. A small group of six veterans travelled with the Deptherapy Instructor Team to the charity’s international base at Roots Red Sea to undertake practical Scuba Diving training in the clear, warm waters of the Red Sea.

Joining Team Deptherapy for the first time was 20 year old paraplegic Corey Goodson who had this to say: “I have been made aware of a new academic study about the benefits of Deptherapy. Last week I learned to scuba dive properly with Deptherapy, a huge achievement for someone with paraplegia. Deptherapy doesn’t judge your injury, whether that be physical or psychological; it looks beyond, and it sees the person inside. That person is who they work with, and the Deptherapy programme encourages you to see your fellow beneficiaries in the same light. More important than the sense of achievement during the training, was the support, care, encouragement and love the team showed me. I have found a new family in Deptherapy. I am home now but the support, friendship and banter continue; it is motivating and empowering, it gives me a deep sense of wellness and worth. I look forward to continuing my rehabilitative journey with Deptherapy.”

For more information about the work of Deptherapy and Deptherapy Education visit

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Dive Training Blogs

Deptherapy returns to its Roots – Part 6



Join Richard Cullen from Deptherapy for part 6 of his Blog about the charity’s recent expedition to Roots Red Sea, El Quseir, Egypt.

Thursday has dawned and it is down to the House Reef with an outgoing tide that is approaching slack so we can get in the water straight away.   Lots of chat about last night’s RAID O2 Provider session with Moudi.  Oatsie is talking about sidemounts and marine biology, Swars is looking forward to his first sidemount session this afternoon.

Moudi is supported by Oatsie this morning and doing some more skill work with Keiron.

Moudi running the guys through the RAID O2 Administrator Course

Corey was asking last night about what it is like at 30 metres, so I have decided that with Michael and Swars we will take him to 30 metres.  We are going to run a narcosis exercise so out comes the slate with the numbers 1 – 25 randomly placed in squares.  Corey’s task, in the dive centre, is as quickly as possible to touch each number in sequence.  He does it pretty quickly and Michael briefs him that he will need to do the same exercise at 30 metres.

Michael briefs the dive and we set off down the beach.  Corey has improved beyond measure and he is becoming a pleasure to dive with.  So we are off to follow the South reef to 30 metres where we will complete the second part of the exercise.

At 30 metres Michael hands Corey the slate; there is a considerable difference in the time to complete the exercise at the surface and at 30 metres.  There are lots of mitigating factors in how quickly you can identify the numbers and explaining a slower time at 30 metres than at the surface does not mean an individual is suffering from narcosis.  Identifying random numbers, if you run the exercise at the surface, several times with an individual over a number of hours can result in wide variations in the time taken to complete the exercise.

We finish the dive with Corey smiling from ear to ear and we have a discussion about depth and air consumption.  The second dive of the morning is a fun dive, then it is lunch in the beach restaurant.  After the burgers I am sure we will need to look at our weighting before the afternoon’s dive.

We will need to look at weighting after this lunch!

Corey and Keiron have got into the habit of recording their dives online using the RAID online log book which is a tremendous facility and as the instructor I can access that data.

Moudi and Keiron are going for a fun dive as are Corey, Oatsie, Michael and myself. Swars is getting kitted up for the first experience of sidemount with Guy Henderson.

Swars getting to grips with his sidemount cylinders

People often look at the relationships that exist between the dive team and our beneficiaries and try to extrapolate a similar relationship to disabled students they might have.  Our relationships are built up over a period of time, in some cases over many years.  We also provide 24/7 support and have chat groups etc on social media; we also meet up socially when we can.  It is somewhat different than a individual coming in to a dive centre and saying ‘I want to dive’. Your relationship is likely to be the same as any other student, you will teach them, they might stay with the dive centre or like many that will go on holiday to do some diving, you might never see them again.

Our main aim is to create a family atmosphere for our programme members, one where they feel secure and they are able to discuss freely with the team and fellow beneficiaries their feelings and needs.

Few dive centres are charities, and owners might want to consider costs of running a course for someone with a disability that might take more than the standard four pool sessions etc.  You may find the number of sessions and the staffing levels have to increase.  Many dive centres, because of their size and turnover are exempt from providing accessibility.  How will this affect someone who is a wheelchair user?  Can they gain access to the dive centre, the classroom, the toilet?  What are the changing facilities, can they get wheelchair access to the pool?

Lots of things to think about.

Roots’ beautiful reef

The reef is beautiful, so much aquatic life and the corals look splendid, especially the pinnacles.

A good day’s diving, Swars has really enjoyed his sidemount.

Lovely way to relax in the evening with the Roots BBQ, a fitting end to a great day.

Last day tomorrow and our final blog!

Find out more about the work of Deptherapy and Deptherapy Education at

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