September has seen the wildest sea conditions of the year here on North Island, with swells reaching close to four metres and winds of up to twenty knots. Beneath the waves however the water has remained clear with visibility consistently 15 metres or more and sea temperatures warm 27 degrees Celsius, making for fantastic diving.
In a month that has seen sharks in Seychelles hitting the headlines worldwide, it has been business as usual on North with daily shark encounters at our local diving sites. Ever friendly and calm, the white-tip reef and Indian Ocean nurse sharks have been frequently spotted and our occasionally evasive grey reef sharks have been seen several times this month. Divers have been able to drift through the water side by side these beautiful animals on several separate occasions.
Without doubt the most exceptional sighting of September has been what divers refer to as a Spanish Dancer, or Hexabranchus sanguineus, in the shallow waters surrounding our neighbouring Silhouette Island. This beautiful nudibranch has its common name thanks to its incredible ability to swim with graceful undulations of its mantle margins. Since it can grow larger than 40cm in length, it was believed that there were several different species of 'Spanish Dancer' until the 1970s when they were combined into one single species.
In recent years another giant species of nudibranch has been discovered and named the 'Djibouti Giant' - recorded at 52cm long. Unlike Hexabranchus sanguineus, which literally translated means 'six gills', this rare giant, found solely near to the entrance of the Red Sea off the coast of Djibouti, possesses only four.
As is true with all nudibranch species, the Spanish Dancer is characterised by its bright colours, duel rhinophores (club-like protrusions on the head) used to detect odour, and celaphic tentacles sensitive to touch, taste and smell. Always a treat for divers, most nudibranchs require a well-trained eye to be detected, a discretion these giants do not possess!
Furthermore, divers and snorkellers have been treated to pods of bottlenose dolphins circling our boats whilst heading out on dives in September. Always reluctant to approach too closely, these incredibly intelligent animals have a famously playful and inquisitive character as one particular snorkeller found whilst in the water at Sprat City. From out of the blue came the dolphin, staying close to the observer for a minute or so before heading back on his way. Bottlenose dolphins hunt in groups, driving shoaling fish into tight balls just beneath the surface using bubbles, swimming manoeuvres and warning cries. Growing up to four metres in the length and weighing up to 600kg, bottlenose dolphins are not normally spotted on their own as this one was and are more commonly found in pods ranging from three to fifteen individuals. In open seas however, groups of up to 600 can occur.