Hope you had a great November! Here's some new content I posted this month, in case you missed it:
- Whitefin Hammerhead Shark Profile
- Smalleye Hammerhead Shark Profile
- Carolina Hammerhead Profile
- Commerson's Dolphin Profile
- Rough-Toothed Dolphin Profile
- What Is Cetacean Morbillivirus?
It's hard to believe December is just about here. It sneaks up on me every year, it seems. If there's content you'd like to read about here on this site, send me an email at marinelife(at)aboutguide.com or comment below! Hope you have a wonderful holiday season!
For readers in the U.S., I hope you have safe travels this week and a wonderful Thanksgiving (and hopefully long weekend) with friends and family. Thank you for reading my blog and exploring the marine life site! If there's content you'd like to see in the coming year, please feel free to comment here or e-mail me at marinelife(at)aboutguide.com.
Cetacean morbillivirus...Now there's something to ponder on your Thanksgiving travels this week!
As you may have heard, since July 2013, a large number (889 as of November 24) of bottlenose dolphins have stranded along the eastern coastline of the U.S. from New York to Florida. This number is well over the normal numbers of stranded dolphins - the average for this time period over the last five years has been 112 animals per year.
What is causing these strandings? All of the stranded animals haven't been examined so far, but based on preliminary investigations, the National Oceanic and Atmospheric Administration (NOAA) has tentatively labeled the cause as cetacean morbillivirus. This is a virus that is in the same family of viruses that causes measles in humans and canine distemper in dogs, coyotes, wolves and seals. The virus most commonly seems to affect the animal's lungs and brain. Affected animals may be thin, have respiratory difficulty, have skin lesions, and behave abnormally. In addition, morbillivirus weakens the immune system, leaving infected animals susceptible to other diseases and infections.
Cetaceans can contract the virus through airborne particles, or contact with infected cetaceans. As far as humans are concerned, it cannot be contracted by humans, but it is possible that a stranded animal has an additional illness that can be transmitted to people or their pets, so you should always observe a stranded animal from a distance (100 yards or more) and alert your local stranding response team if you find an animal on the beach. For a list of stranding response numbers by state, click here. There is also an app (Android, Apple) that allows you to report a stranded animal in the Southeastern U.S..
- What Is Cetacean Morbillivirus?
- Bottlenose Dolphin Profile
- Southeast Marine Mammal Smartphone Apps (NOAA Fisheries)
Image: Bottlenose Dolphins, courtesy NOAA
Earlier this month, the discovery of a "new" species of shark was reported. This shark, christened the Carolina hammerhead, was reported in the journal Zootaxa by Dr. Joe Quattro, a professor at the University of South Carolina, and colleagues.
Quattro was researching the genetic makeup of fish in South Carolina rivers, when he discovered a new genetic signature in what he thought were samples of scalloped hammerheads. It turns out this animal was genetically distinct and also had 10 fewer vertebrae than the scalloped hammerhead. Quattro's team then looked at the scientific literature and found a discovery by icthyologist Carter Gilbert in 1967 of an anomalous shark that looked the same as a scalloped hammerhead, but had 10 fewer vertebrae. The "new" shark (which had really been there all along, it just hadn't been officially described yet) was scientifically named Sphyrna gilberti in recognition of Gilbert's initial discovery.
The Carolina hammerhead is known as a cryptic species - it looks the same as another species, but its distinctiveness is "hidden" until you look at its genetic makeup. As scientists look at the DNA of more and more species, the discovery of these cryptic species is becoming more common, which raises interesting discussions around conservation. If scalloped hammerheads are endangered, is the Carolina hammerhead even more endangered? What is the true range of these cryptic species and how can they be protected? Are existing protections adequate? It will be interesting to learn more about the Carolina hammerhead as scientists uncover new information.
These dolphins live in the Southern Hemisphere. There are two subspecies of Commerson's dolphins - one known as the Commerson's dolphin, which lives off the southern part of South America and around the Falkland Islands, and the Kerguelen Islands Commerson's dolphins, which live off the Kerguelen Islands in the Indian Ocean.
These dolphins, as you can see from the photo here, have a striking black and white coloration. Another feature is on their flippers - adults often have a serrated edge on one or both of their flippers. Interestingly, this serrated edge is most often on the left flipper, especially in males. The function of the serration is unknown, although one theory is that it allows for more tactile simulation if a dolphin rubs another dolphin with its flipper.
Have you ever seen a Commerson's dolphin in the wild, or in an aquarium?
With its sloping head and long beak, the rough-toothed dolphin looks a little primitive in appearance.
This species is found in warm temperate and tropical waters around the world, and is considered relatively abundant. However, since it spends much of its time offshore, the biology and life history of the rough-toothed dolphin is not well understood.
These dolphins get their name from the ridges and wrinkles on their tooth enamel. They have 20-27 teeth in each side of their upper and lower jaw.
Learn more about the rough-toothed dolphin here.
Image courtesy Sophie Webb, Southwest Fisheries Science Center, NOAA Fisheries Service
Now, do you know the largest sea turtle species? Click here for the answer!
Kemp's Ridley turtles were named for fisherman Richard M. Kemp, who first described them in Florida. These turtles may be found in the Gulf of Mexico, and the Atlantic coast from Florida to New England. They have also been seen near the Azores, Morocco and in the Mediterranean Sea.
Image: Kemp's Ridley Sea Turtle Hatchling, Courtesy USFWS