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| Rough-toothed Dolphins Quickly Swimming; Gulf of Mexico: Geco Snapper 04.2008 |
After whales continually greeted me on my adventures offshore, I was rather used to seeing these magnificent creatures randomly pop up everywhere- “My Favorite Bostonian Cetaceans; Dive into a World Different from Our Own” and “The Pursuit for the Sperm Whale; the Great Legend of Moby Dick.” Not to mention on the fabulous projects the Texas Horizon and the Viking Vision, I kept spotting numerously large pods of whales. I had seen several sightings of dolphins, but the whales seemed to outnumber them. At this time, I was ready for a change – maybe a large pod of dolphins will excitedly approach my boat? I wanted a few whales to drop by at the Geco Snapper, but strangely during the full 8 weeks offshore I had none! I grew rather fond of the Sperm whales and kind of scratched my head in confusion where the whales were headed, definitely not in my general direction! Instead I sighted a few sightings of dolphins, which comprised of two specimens: 1) Bottlenose dolphins; and 2) Rough-toothed dolphins.
You have seen Flipper, right? This delightful creature that had captured our hearts was actually a Bottlenose dolphin. I learned recently that in front of the Dolphin Research Center (DRC) in Grassy Key, Florida (which is just south of Miami) stands a 30-foot concrete statue of a mother and baby dolphin. This was the final location where Mitzi aka Flipper spent her last few days. What did she die from you may ask? A heart attack – I had no idea how similar dolphins really are to humans; they are such incredible beings. Unfortunately, on this project I was not able to photograph any close-ups of Bottlenose dolphins, but lucky for you I have some great shots of these adorable subjects for a later post.
On the other hand, I had several close encounters with Rough-toothed dolphins. My favorite memory of sighting this particular specimen was when I standing on the bow of the boat (the front half of the boat) and was in the mist of examining some Portuguese man of wars drifting with the current. Suddenly, I heard a rather large splash behind me, as I glanced over my shoulder I saw what appeared to be a dolphin breaching out of the water! I quickly sighted 6 more individuals staying in close proximity of the larger adult that had just breached. As I carefully watched this pod of dolphins I was perplexed about what this specimen was. I grabbed my trusty marine mammal book and started skimming through the pages to identify this specimen with the provided pictures. Instantaneously, I noticed the lack of long beak or at least a poorly defined beak, which when I glanced at the book it highlighted that these were Rough-toothed dolphins. I have never laid eyes on Rough-tooth dolphins, not even on Discovery Channel! Excitedly I yelled up to the bridge wings and caught Dustin’s attention. He ran down to where I was standing and helped me document their behavior as they breached a few more times, and then quickly swum towards the horizon. I was happy that they dropped by! The final outcome was that I learned of a new species of dolphin that I have never seen before and I enthusiastically welcome the next encounter!
Educational Background on Dolphins:
Dolphins are carnivorous small, toothed whales. Dolphins are found in many parts of the world and within various oceans and even in freshwater rivers of Asia, Africa, and South America. Did you know that an Orca or Killer whale is actually a dolphin? Dolphins also belong to the order Cetacea, which means that they are mammals fully adapted to aquatic life. Dolphins are part of the Delphinidae family, which in this particular family consists of highly intelligent aquatic mammals. A common assumption is that dolphins are fish – dolphins are not fish; they are, in fact, mammals. The dolphin refers to the species that have a slender beak-like snout and streamlined body, which have in return developed during the Miocene, nearly 10 million years ago through evolution to enable their ability to swim extremely fast at great speeds.
How many different kinds of dolphins are there you may ask? Surprisingly, there are over 33 different species of dolphins, over 5 distinct species of river dolphins, and over 6 separate species of porpoise. One intriguing fact that I learned in high school while researching information on dolphins were that they can reach speeds of 35mph.
As we discussed the theories of echolocation – “The Pursuit for the Sperm Whale; the Great Legend of Moby Dick;” we learned a greater understanding of how dolphins actively communicate. To summarize this past segment, echolocations or sonar is the method that a dolphin exercises to locate and distinguish between objects underwater. Cleverly, the dolphin emits a sound and listens to the echo – in response, the powerful clicking noises comes from the melon which subsequently travels through the water, and then bounces off the objects and returns back to the dolphin. What is the importance of the melon you may ask? The melon along with the lower jaw is filled with a jelly-like substance used to amplify sound waves. As a dolphin swims, it moves its head back and forth to scan its surroundings – the echoes it sends out bounce off objects and hit the lower jawbone, which conducts the returning sound waves to the inner ear. By the pitch of the returning echo and the time it takes to get there, the dolphin can determine the shape, size, speed, texture, and density of the object. Shockingly, a dolphin can even view the inside of an object, almost like an x-ray, except it substitutes vision by sound. In addition, echolocation helps the dolphin navigate through the water avoiding predators and other dangerous situations.
Another form of communication that is utilized by dolphins is recognized as vocalizations. What are vocalizations you may ask? Just like a human has the ability to communicate with noises that are formed into words, dolphins have the same benefits. For instance, vocalizations are representations of various noises that come from their blowholes. On the other hand, signature whistles or squeals that are also practiced by dolphins for communication purposes are a great indication of them expressing their emotional status.
Shocking Facts: Like the whales, the most dangerous predators for dolphins are humans. In fact, all river dolphins are in serious danger of extinction due to pollution and man-made dams. The Whitefin or Baiji dolphin is the world’s rarest cetacean. The current estimation of the population is a staggering 100. With this being said, there is no definite time on how long these creatures will thrive. I have read several articles about the Lipotes vexillier’s survival and sadly enough it does not look promising.
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| Rough-toothed Dolphin Breaching; Gulf of Mexico: Geco Snapper 04.2008 |
A Detailed Description of a Rough-toothed Dolphin:
The Rough-toothed dolphin (Steno bredanensis) is commonly mistaken for the Bottlenose, Spinner, and Spotted species, but upon closer inspection observers note unique physical characteristics specific to this animal. When I originally had sighted the pod of dolphins my automatic assumption was that these were Bottlenose dolphins.
Throughout my sightings of the Rough-toothed dolphins I noticed a number of unique characteristics which defined this marine mammal. Rough-toothed dolphins appear to wear a mask, hood, and cape which range from dark grey to black in color. The markings begin at the tip of the nose and extend back past the dorsal fin. The lips, throat and underbelly are in stark contrast with hues of white to pink. The belly surface is further marked with irregular grey or black splotches. The nose or beak is long, round and gently curves to form a small head. The body is stocky in appearance having dorsal and pectoral fins located further back on the body compared to other dolphins. Additionally, the fins are much larger in size. This playful sea mammal was aptly named for the wrinkled ridges on the crowns of the 22 to 27 large teeth within its mouth.
Rough-toothed dolphins prefer deep tropical waters around the world. They are very social creatures not only amongst their own kind, but with other dolphin species, some whales and fish. In fact, the Rough-toothed dolphins have been known to produce hybrid offspring with other dolphin species while in captivity. The Rough-toothed dolphin is known to travel in groups as small as 8 and in communities numbering in the hundreds. Researchers estimate the total worldwide population to be over 150,000 and this dolphin species is not currently considered endangered.
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| Rough-toothed Dolphins Slowly Swimming; Gulf of Mexico: Geco Snapper 05.2008 |
5 Fun Facts about Rough-toothed Dolphins:
Did you know?
Do they stay within their own species or do they travel with other pods as well? Rough-toothed dolphins have been known to associate with the Bottlenose, Spinner, and Spotted species. A matter of fact, on the Geco Snapper, I observed 2 Rough-toothed dolphins swimming with a pod of Bottlenose dolphins.
Do they attack each other? Like other marine species, Rough-toothed dolphins may show scars resulting from encounters with other marine life such as sharks, squid, and other Rough-toothed dolphins.
Do they sleep? Traveling as much as they do, Rough-toothed dolphins must rest some time. They do not sleep, though. They merely take cat naps at the ocean’s surface for two or three minutes at a time. At night, those naps increase to seven or eight minutes.
Do they bow ride? Frequently Rough-toothed dolphins will accompany boats, riding the bow waves. They are also famous for their willingness to occasionally approach humans and interact with them in the water. In return, in some cultures like in Ancient Greece they were treated with welcome; a ship spotting dolphins riding in their wake was considered a good omen for a smooth voyage.
What do they eat? The Rough-toothed dolphin feeds on fish and squid as well as mollusks and cephalopods.
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Conservation Status:
Rough-toothed dolphins are world widely affected. For instance, Rough-toothed dolphins are hunted for food in some regions. They are harpooned in Japan and West Africa. Entanglement in fishing gear poses a threat, and Rough-toothed dolphins have been reported caught in purse seines in the eastern tropical Pacific. Others have been reported caught in gillnet and driftnet fisheries in Sri Lanka and Brazil. Pollutants have been detected in blubber analysis of Rough-toothed dolphins in Hawaii.