Dolphin Tales: Dolphin vs. shark
A group of researchers from Florida Atlantic University have been studying sharks and dolphins off the coast of Bimini in the Bahamas. Bimini is just 55 miles off the coast of Miami. It’s part of the 700 islands that make up the Bahamas and is the closest point to mainland U.S.
The researchers, Dr. Mike Heithaus and Dr. Valerie Paz, have discovered that nearly one third of the dolphins found in this area show signs of shark attacks. The team is studying the Atlantic spotted dolphin and the Atlantic bottlenose dolphin.
The researchers use a non-toxic gel bite pad and a life-sized dolphin decoy to collect bite impressions from bull sharks, tiger sharks and the great hammerhead. The bite impressions are compared to scars photographed on the Bimini dolphins.
While foraging for food, some dolphins break away from the pod to crater feed. This is a dangerous time for shark attacks as the dolphin goes solo. Swimming in pods protects them from the shark predator. Dolphins are fast, intelligent and their brain to body mass is second only to humans. Echolocation is their super power. But when they are alone, they are most vulnerable.
When a dolphin breaks away to crater feed, the dolphin will execute a rapid 90-180 degree turn and then dive, thrusting its rostrum into the sand to obtain its prey by echolocation. The dolphin dives headfirst into the sand and remains upright while it forages. This is when the shark takes its aim.
There are at least a dozen species of sharks off of the east and west coast of Florida including 10 types of hammerhead sharks alone. They hang out in the shallows of the Bahama banks. Baby dolphins, when separated from their mothers, are particularly vulnerable to these huge sharks. Tiger sharks and bull sharks are ambush predators that sneak up on their prey.
The peduncle of the dolphin is the bullseye for the shark. It is just above the tail fluke and is the power source for the dolphin and also where the base of the spinal cord is. Coming from below and behind is the best way for a shark to attack a dolphin because if the dolphin can see the shark, the dolphin has the advantage. The dolphins’ ability to communicate and send out a distress signal is paramount.
Bull sharks and dolphins hunt in the same area along the Bimini coast. Given the chance, the sharks will attack a dolphin which has wandered from the pod. The dolphin offers a really rich meal with lots of meat and blubber.
When it comes to humans, the tiger shark is second only to the great white shark with attacks. Weighing nearly a ton, they will eat just about anything from tires, to turtles, to dolphins and humans. Once they get a hold of their prey, they shake and with their curved teeth with striations, they can cut right through.
Captain Cathy Eagle has spent over 40 years boating on our local waters. As a professional charter captain, she specializes in dolphin and nature tours. Visit CaptainCathy.com or call/text 239-994-2572. Welcome aboard!