Bat rays (Myliobatis californica) by Amanda Cotton
Bat rays are euryhaline - they can survive in a range of salinities, which is no mean evolutionary feat ‘cos osmoregulation is complicat-ed.
Check out more of Amanda’s elasmobranch adventures here.
Mating Nudibranches (Roboastra luteolineata) SMURF PENIS
On a recent dive, we stumbled upon a rather private moment between a couple of simultaneous hermaphrodites, Roboastra luteolineata, doing the mutual penis dance. They were poking around for a while, and had yet to manage mutual fertilization when we (reluctantly) moved on.
Some of you might have found, that after a hundred dives or more, that although you still enjoy reefs, or fish, or the ‘prettiness’ of being underwater, that other aspects of the marine world take your fancy. I have zoomed in on macro life, and relish the challenge of finding tiny critters on a sandy bottom. And for the things that are a bit bigger, behaviour starts to catch your eye…
…who am I kidding? It’s all about the smurf penis.
This megamouth shark was fished in the Philippines on April 21, 2013. The megamouth shark (Megachasma pelagios) is an extremely rare species of deepwater shark, so rare that only over 50 sightings have been recorded since its discovery in 1976.
Of the now 56 megamouth sharks recorded worldwide, 11 specimens (20%, most numerous next to Japan) come from the Philippines.
The megamouth is the smallest of only three filter-feeding sharks (the others being whale sharks and basking sharks).
Photo from CJ Fives for Butuan Bay Divers.
How Animals Eat Their Food (by MisterEpicMann)
“Various processes are known to enhance the ocean’s ability to store carbon. Sperm whales increase the levels of primary production and carbon export to the deep ocean by depositing iron rich faeces into surface waters of the Southern Ocean. The iron rich faeces causes phytoplankton to grow and take up more carbon from the atmosphere. When the phytoplankton dies, it sinks to the deep ocean and takes the atmospheric carbon with it. By reducing the abundance of sperm whales in the Southern Ocean, whaling has resulted in an extra 2 million tonnes of carbon remaining in the atmosphere each year. “
As if sperm whales weren’t cool enough already.
Travels of Pregnant Great White Sharks Revealed
by Douglas Main
For the first time, migrating great white sharks have been tagged and their movements around the oceans tracked for years, as opposed to the few months they have previously been tracked, according to a researcher.
Scientists used special satellite tags that tracked several sharks from a specific great white population for up to three years off the coast of Mexico. The study found that adult female sharks complete a two-year breeding cycle and avoid male sharks whenever possible, said study author Michael Domeier, a researcher and the president of the Marine Conservation Science Institute.
Published recently in the journal Animal Biotelemetry, the study followed four female great white sharks from their mating grounds off Mexico’s Guadalupe Island until they returned 24 months later, Domeier said. During the first 18 months, the females followed an ambling path through the open ocean, he said.
They then arrived in off Baja California to give birth to shark pups, putting themselves at risk of running into shipping traffic on their voyage along the shore, the study found.
“During the time the females are giving birth along the Baja Peninsula they are exposed to an array of commercial fishing activities that put them at risk,” Domeier told OurAmazingPlanet in an email. “Of course, the baby white sharks are at even more risk since they spend the first years of their life in coastal waters and their small size makes them even more susceptible to capture.”
Once the young sharks are born, the females return to Guadalupe Island to mate again.
The study found a high prevalence of bite marks on the sharks. Male sharks “bite the head, flank or pectoral fin of females during the mating ritual, but certainly these sharks are biting each other out of aggression as well,” Domeier added. “Males may be battling it out for access to females or preferred hunting grounds.”
While the females return to mate every two years, the males only return every other year. When they’re not mating, both males and females may range as far afield as the waters off Hawaii, Domeier said.
The researchers tag the great white sharks by affixing the device to the tip of the animal’s dorsal fin, during which time they are very close to the predators.
“It’s surreal and humbling,” Domeier said. “It is also stressful since the shark’s life is in our hands during the short time it takes us to capture and tag each individual.”
Source: Live Science
Photo Credit: Neil Hammerschlag
100 years of unprovoked shark attacks (1912-2013)
Andrew Barr and Richard Johnson | National Post
Surfer numbers have increased dramatically since the 1950s and advances in wetsuit technology mean people are going into the water all year round and staying out in the surf for longer periods, all of which increases the odds of someone being attacked by a shark. With this in mind, the National Post’s graphics team takes a look at the century in unprovoked shark attacks.
Blue = Male survivor
Pink = Female survivor
Black = Fatality
Looks pretty colourful to me.
Read more here including a break down of activities during the attacks and a close up of injury location (if any).
This is a great visual back up for this (Attn: NERDS: Free journal article). Remember when I posted about a new paper seeking to reclassify human-shark interactions? No? That’s ok. Here’s a snippet from the abstract:
There are few phrases in the Western world that evoke as much emotion or as powerful an image as the words “shark” and “attack.” However, not all “shark attacks” are created equal. Under current labels, listings of shark attack may even include instances where there is no physical contact between shark and human. The dominant perception of intent-laden shark “attacks” with fatal outcomes is outdated as a generic term and misleading to the public. We propose new descriptive labels based on the different outcomes associated with human–shark interactions, including sightings, encounters, bites, and the rare cases of fatal bites. We argue two central points: first, that a review of the scientific literature shows that humans are “not on the menu” as typical shark prey. Second, we argue that the adoption of a more prescriptive code of reporting by scientists, the media, and policy makers will serve the public interest by clarifying the true risk posed by sharks and informing better policy making.
A fisherman recently caught a bull shark of the Florida keys and found something pretty unusual inside - a fetus with two heads.
Very few examples of two headed sharks have ever been recorded. This is only the sixth known case, and the only time it has been observed in bull sharks. The condition is the same as in human “conjoined twins” - the embryo begins to split, but does not do so completely.
More info: http://bit.ly/11DHfpk
Feeding Indian mackerel (Rastrelliger kanagurta)
With a collective sigh of relief we can celebrate a MAHUSIVE step forward for elasmobranch conservation today!
Oceanic White Tips, Porbeagles, three hammerhead species and Manta Rays have been listed under CITES Appendix II meaning the trade in their parts will undergo international restrictions!
On top of that, Sawfish we’re upgraded to Appendix I which means no trade at all!
This is a historic, unprecedented and long overdue step forward for our oceans. A changing of the tide if you will.
Congrats to everyone whose blood, sweat and tears made this possible!
Read more: CITES4sharks press release