A Certain Type of Thrill
There is a certain type of thrill in waiting for a bull sperm whale to approach underwater. This male was around 17 metres long. The ocean shelves precipitously around the volcanic pinnacles of the Azores and the deep water is impossibly blue. Like a mirage, the whales emerge from the gloom. Sometimes they dive and and avoid you. Sometimes you get lucky and they glide right by.
This bull was curious and passed so close I could have reached out and touched him. Dappled sunlight imprints a mosaic pattern on his head. Rake marks are clearly visible. Maybe these are scars of battle with other males however we have observed whales gently mouthing each other during marguerite formations.
From the Surface
The surface view of the same encounter. The whale rolls onto to its side so it can clearly see 'the creature' ahead in the water. Their eyes at at the back of the head and the head may be nearly a third of the body length. Sometimes sperm whales will arch their head to see forward. Once I had past his head, this whale rolled back to the horizontal and graciously lifted his flukes and I passed underneath.
Sperm Whale Vocalisations
Sperm whales are capable of an generating an impressive amount of noise. Their vocalisations have been recorded at 223 decibels, the loudest biologically generated noise known. These vocalisations are used to hunt and detect prey and also for long distance communication and social interaction.
The top image shows a hydrophone audio recording of an encounter with a 17 metre bull of the south coast of Pico Island on July 2 2008. Sperm whales emit 'echo location' clicks through the oil-filled spermateci organ, the bulbous part of the head.
The recording (courtesy Wade Hughes) shows a low level of repeating clicks as the whale aproaches me. As he closes, he interrogates me with two high powered bursts that I could feel in my chest and rattled my facemask. Fortunately this is not a sign of aggression, the whale is merely using biologically available tools to check what lies ahead - much as the same as we use an echo sounder. This has occurred on a number of occasions when I have been in the path of an approaching male.
Mind you, this is the last sound that prey such as giant squid may feel or hear.
The lower image shows 'slow' or 'usual' clicks heard as whales go about their business. This must be reassuring to calves as they track their mother's movements from the surface whilst the mothers are on long foraging dives (40-50 minutes) to depths of 1000 metres or more.
Special Moments in Time
it's an incredible privilege to share moments in time with these intelligent mammals. The above three images are of a young curious female about 7-8 metres and maybe 2-3 years old. She was very curious and quickly swam in, circled me twice and did a barrel role before heading back to her pod.