Friday, March 27, 2009

Rough-toothed Dolphin Echolocation - I Was Scanned Thoroughly!

For over a decade, I've searched for a good opportunity to shoot the rough-toothed dolphin, Steno bredanensis. The rough-toothed dolphin is not common but one of the four species of dolphins that are regularly found off the chain of Hawaiian Islands.


Particularly in Hawaii, they usually make a tight pod of ten to thirty dolphins. That is very small compared to Hawaiian spinner dolphins, Stenella longirostris longirostris, and pantropical spotted dolphins, Stenella attenuata, which can make up a pod of fifty to a few hundred dolphins easily.


rough-toothed dolphin, Steno bredanensis, Kona Coast, Big Island, Hawaii, USA, Pacific Ocean

They also look somewhat weird if you are used to seeing common dolphins like bottlenose dolphins, Tursiops truncatus, in captivity. Their melon-heads are not protruding as much, and actually have no distinctive ledges or recesses to separate them from the beaks, that give them impression of large elongated beaks. Their genus name, Steno, means "narrow" in Greek and refers to the conical slender nose which characterize this species.

Their dorsal fins are relatively larger and taller and look more like shark fins in the field of the ocean. They also have rather peculiar gray to black coloration and patterns. Adults have more distinctively black & white colorations, many are blotchy around their bellies.  They also develop white lips and usually marked by numerous cookiecutter shark, Isistius brasiliensis, bite wounds and battle scars.


rough-toothed dolphins, Steno bredanensis, mother and calf, Kona Coast, Big Island, Hawaii, USA, Pacific Ocean

They are much harder to find compared to other dolphins in Hawaii. They are small, but highly intelligent. Fishermen don't like them at all because they "steal" their catches off their fishhooks without getting themselves hooked. Usually when rough-toothed dolphins show up, fishing is over. Hawaii's fishermen have many tricks to deal with sharks which also steal their catches, but rough-toothed dolphins usually outsmart fishermen.

I've had fair shares of encounters with them in the past, but never had a decent opportunity to satisfy my appetite for good photography until this day. It was a calm beautiful day, but it seemed like one of those days that dolphins were occupying the fishing ground and most of fishing boats started leaving as they were giving up on fishing.

I didn't want to engage in an intense tag of wars with dolphins, either, so instead, I decided to check out dolphins and fish underwater.


rough-toothed dolphin, Steno bredanensis, analyzing the photographer by using impulse-type (click-type) sonar for precise echolocation and imaging, Kona Coast, Big Island, Hawaii, USA, Pacific Ocean

As soon as I entered in the water, those dolphins came by to investigate me at very close range. I was totally surprised at that because they normally stay away from divers, just far enough not to get their pictures taken. They totally behaved differently on this day. Maybe they were bored and needed to something to do, or full and sleepy.... in any case, they were in a right mood to play with me and  was a golden opportunity to photograph.

As soon as the dolphins discovered me, they got very busy scanning me from the top of my head to the tip of my diving fin. They were using the impulse-type sonar so I can hear the loud clicking sound clearly, and actually I can feel it on my body underwater as they were buzzing me around from 5 to 10 feet away.

I don't know how many times I was scanned, but they must have echolocated and examined every content of my body, and perhaps learned what I ate for lunch on that day.

The encounter lasted about one hour or so until I got tired of swimming. Sometimes I followed them, but  most of the time they followed me around. It was simply amazing, and I'm very pleased with resulting pictures I've got.

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