A bottlenose dolphin surfaces with a scrape on the front of his dorsal fin, the third of four wounds this summer. Like the kid who skins her knee repeatedly all summer long, are its scrapes due to outside circumstances, the kid’s own habits, or a little of both?
The autumn seas are a time of transition the way afternoon is the shift from noon to night. On land, the weather changes leisurely; you have to pay attention. At sea, dolphins also transition leisurely. Again, you have to pay attention because some obvious clues are only obvious in retrospect.
A huge gray dolphin ascended from the sea floor. Exhaling heavily as he cleared the surface, he created a small geyser of water and showered in it. A smaller dolphin rose next to him, breathing the silent breath of a new mother. Her teeny six-week-old baby squirted up between them.
Schnoz, Stick and her baby ambled through jade-colored waters between islands. When Stick’s baby blurted to the surface, Schnoz surfaced with it simultaneously.
Experienced adult dolphins do this for newborns. It gives newborns a rhythm to follow and perhaps a wave of water to ride like an invisible magic carpet. The big bull’s dorsal fin was enormous compared to the teeny dorsal fin that surfaced in its shadow.
Swimming with newborns is a rare pastime for bottlenose bulls. But Schnoz is a singular bull in many ways. He confirmed this clearly over the dozen times Capt. John Heidemann and I have seen him this year. What Schnoz did not clearly confirm were the many obvious clues he left. It took us all summer to see them. Finally, though, we discovered another of Schnoz’ idiosyncrasies. Maybe.
Schnoz’ idiosyncrasy pertains to his massive dorsal fin. The dorsal fin is the fin that sticks out of the water when a dolphin surfaces to breathe. What does he do with his fin?
The dolphin dorsal fin is a target for toothraking. Sometimes toothrakes also scrape the narrow front of the dorsal fin. More rarely the front of the fin is scraped but there are no other marks. In a watery world where dolphins avoid docks and other things that could scrape the front of the fin, the front of the fin is difficult to scrape. Thus I note every episode and wonder how they manage it.
One recent September day, Schnoz zinged past like a Ping-Pong ball. I glimpsed the scrape on the front of his fin and wrote: “leading edge wound from this spring is taking a long time to heal. It is as if there is a bulge of blubber pushed out from bottom of wound. Wound is still flesh colored. It will leave a big dent in his dorsal fin.” Remembering that Schnoz had scrapes on the front of his fin last April, I added, “This is an example of how long it can take to heal a dolphin appendage.”
Does it really take six months for a little scrape to heal? When I got home, I looked up that April date. A mystery was at hand. It was soon solved, which is why data are such fun!
The punch line: Schnoz had four consecutive injuries to the front of his fin that looked like one wound that took 6 months to heal!
Wound 1 appeared by April 2013. Squiggly little flesh-colored cuts looked like strands of vermicelli stuck on the fin. Two weeks later, the “vermicelli” had widened into “fettuccine,” forming fleshy cracks through the surrounding gray skin. A month later in May, the fleshy fettuccine had faded (healed) to light gray.
Wound 2 soon appeared. By June 2013, Schnoz was toothraked again with a jagged notch on the front of his fin as well. Was it another spring battle of the bulls? By July, the notch was bigger, deeper and more jagged. Oddly, it also bulged with a bit of blubber the size of wad of chewing gum.
Sixty-five years ago, John Lilly demonstrated that dolphin blubber bulges into and seals any breach of the skin. Lilly did this by punching metal straws of various diameters into captive dolphins (ouch). Blubber bulging prevents bleeding at sea. This is good because bleeding at sea attracts the wrong company.
It is very rare to see blubber bulging into John’s Pass dolphin wounds at sea. I wondered if the blubber we saw bulging out of Schnoz' wound was related to his own machinations. Did he rub the scrape the way I rub a healing bruise?
Like an assembly line, wound 3 appeared by August 2013. Though Schnoz’ scrape was “still bulging” with blubber, careful comparisons of photographic data showed that Schnoz had a new scrape right below the one he got in June. But this scrape was clean, as if from a knife. The June scrape was jagged, perhaps from serrated teeth.
Wound 3 soon bulged with blubber, which lasted a whole month but also changed shape over time. It waxed, waned, and then doubled in size. A curious thread arose from it like a poised Lilliputian rocket. The changes made me wonder if Schnoz has been itching or rubbing his wound, or if his own activities has created the wound.
Each of the scrapes on the front of Schnoz’ fin healed to a little bump of light gray. The line of tiny moguls from Schnoz’ previous wounds grew again in October when wound 4 appeared. This new one was just below the previous wound.
Oh, Schnoz! What happens that the front of your fin keeps taking a hit? Is it in battle, like the guy who keeps getting a black eye? Are you a rare local dolphin who goes under docks but miscalculates and clips the front of your fin every other month?
Your repeated “skinned knee” could be an idiosyncrasy. Or is it an eccentricity?
Dr. Weaver studies wild dolphins under federal permit 16299, National Oceanic and Atmospheric Administration. Send her an email at email@example.com or visit her website www.goodnaturedstatistics.com. NOAA advises anyone who sees a stranded dolphin in the Gulf of Mexico to call 877-942-5343 or 877-433-8299.