Photographing bullhead sharks
How to take the perfect Photo-ID shot
Galapagos bullhead sharks are nocturnal and benthic creatures, living on or close to the ocean floor. Thus they can often be found hanging out on sandy bottoms underneath rocky outcrops or in crevices during the day.
During the warm season, December through May, the bullheads are usually found in deeper and cooler water and can be spotted while scuba diving. When the water temperature drops in the cool season, June through December, these sharks may also be seen during snorkeling.
They can be easily approached and thus make a nice photographic subject. Besides having two dorsal spines just in front of the first and second dorsal fin, which they use for protection from larger predators, they are of no danger to humans. Nevertheless, keep in mind that we are trying to protect this species, so respect their space and avoid scaring them or coming too close.
Whenever you, your dive buddy, or the dive guide spot a bullhead shark during scuba, avoid stressing the animal approaching one at a time.
The best shots for photo-identification are taken when being on the same level as the shark, hovering closely above the ocean floor. This will also make it easier to sex the animal by the presence or absence of the male reproductive organs, the claspers (see image 1). Their docile behavior makes it easy to photograph the sharks, but please keep in mind to avoid damaging the flora and fauna around you.
Photos should be taken at a 90º angle to the body axis of the shark (see image 2), if possible always of the left side of the shark, which we use in our matching algorithm. If you can provide shots of both sides of the individual, it is even better. The photos don’t have to be award winning. Most important is that they are not blurry, at an angle of approximately 90º and that the region used for the identification process is in the shot (see frame in image 2).
Sharks lay eggs
Bullhead sharks are an egg laying (oviparous) shark species. Since we know very little about where they reproduce and deposit their eggs, observations of the egg cases can help us to identify important habitats. The olive brown spiral shaped egg cases are thought to be found in relatively shallow water (10-15m deep), where females secure the approximately 10cm long cases between rocks and in crevices (see image 2). Please upload your photograph or video of an egg case just as you would report any other encounter
Preparing the images
Some photos are perfect right away, but some need cropping or improvement of the contrast. The preparation of your pictures is simple, yet critical to the identification process. If they are not prepared correctly it may result in a false positive or misidentification.
Ideally when editing photos, you may want to alter several things:
Cropping the photo so that the bullhead shark is full frame will make viewing the natural spot pattern easier.- When cropping, you may also have to simultaneously rotate the photo so that the body is centered within the frame.
- Using photo editing programs like Photoshop or Picasa, you can also alter the contrast and color saturation to make patterns stand out.
Once you have edited your photos, or frame grabs from video, you are ready do directly upload your photos to the bullheads.org website. Every contribution is extremely important, so even if you only have a single photo to upload, you're helping to enhance our knowledge about these mysterious animals.
By supplying us with your email address in your encounter report, the bullhead shark database will automatically notify you if your individual shark is reported or sighted again.
Thank you for contributing to this global effort to protect Galapagos bullhead sharks!