Australian Ghost Shark (Callorhinchus milii)
Also known as the Elephant Shark, Makrepe and the plownose chimaera, the Australian ghost shark is a species of chimaera ( a type of cartilaginous fish) found off of Southern Australia and parts of New Zealand. As its common name suggests the elephant shark has a long snout which resembles a trunk or a plow, this snout is used as a probe to aid the chimaera in finding small invertebrates and fish that are hidden in the sediment. Recently, the elephant shark genome has been proposed to be sequenced as a model species for the cartilaginous fish, as it has a small genome size and could help understand the evolution of early vertebrates.
Phylogeny
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Showing posts tagged elasmobranch
Spiny Butterfly Ray (Gymnura altavela)
Also known as the giant butterfly ray, the spiny butterfly ray is a species of butterfly ray native to shallow waters in the Atlantic. Like other rays the spiny butterfly ray feeds mostly on fishes, crustaceans, squid, and other molluscs. The spiny butterfly ray will rapidly strike its prey with the edges of its pectoral fins to stun the prey before it captures it. To withstand this the spiny butterfly ray has a high mass of muscle in the edges of its fins to deliver a harder blow. Currently the spiny butterfly ray is listed as vulnerable as fishing and trawling have caused their populations to decline.
Animalia-Chordata-Chondrichthyes-Myliobatiformes-Gymnuridae-Gymnura-altavela
Why Shark embryos Gobble Each Other Up In Utero
by Tia Ghose
Shark embryos cannibalize their littermates in the womb, with the largest embryo eating all but one of its siblings.
Now, researchers know why: It’s part of a struggle for paternity in utero, where babies of different fathers compete to be born.
The researchers, who detailed their findings today (April 30) in the journal Biology Letters, analyzed shark embryos found in sand tiger sharks (Carcharias taurus) at various stages of gestation and found that the later in pregnancy, the more likely the remaining shark embryos had just one father…
(read more: Live Science) (photo: mp CZ - Shutterstock)
Bullseye Electric Ray (Diplobatis Ommata)
Also known as crampfish or numbfish, electric rays can emit anywhere from 9 to 220v of electricity from their bodies. The electric ray can emit electric shocks from its two bioelectric organs on each side of its head. Electric rays are the most electro-sensitive animal. They also have an organ in their brain that allows them to control their electricity as well as shutting it of in situations like birthing or mating.
They have poor eyesight thus relying almost entirely on their electricity to find prey, kill and defend. Salt water conducts electricity better, so they typically have a much higher voltage output.
The bullseye electric ray is a saltwater fish that only grows up to about 10 inches long. It mostly lives in sandy areas and uses its fins to skip along the sand. It is nocturnal and spends the day buried in the sand. Like many rays, it is in danger of fisherman over trawling their habitiats.
Steve White: “Not strictly speaking sharks, Echinochimaera (left) and Belantsea were both very strange Chondrichthyans from the famous Bear Gulch formation (a limestone layer laid down in the Mississippian epoch of the Carboniferous period, about 318 mya) in Montana. Would love to do a book of all those weirdos.”
A Ray of Light Thrown on 60 Year Mystery
The unexpected capture of a rare ray found only in a small region off South Australia could help marine scientists validate the existence of the elusive Magpie fiddler ray (Trygonorrhina melaleuca).
The species is listed by the International Union for Conservation of Nature (IUCN) as Endangered, but until now its very existence has rested on a single specimen found nearly 60 years ago off Kangaroo Island. That specimen is stored at the South Australian Museum and was used to describe the magpie fiddler ray species in 1954.
“This ray, caught by fisher John Marsh from the Adelaide Game Fishing’ Club, is pretty much considered the ‘Holy Grail’ specimen,” says Paul Rogers, a researcher with SARDI Aquatic Sciences Threatened, Endangered and Protected Species program. “This is because the species has been described based on one specimen only and up until now, scientists have not been able to study another specimen of the magpie fiddler ray.”…
(read more: Sardi)
(photos: Brett Williamson, ABC Adelaide; Brad Smith)
Mercurial Grey Sharks Dive Deep Under a Full Moon
by Megan Gannon
Over the course of nearly three years, researchers from Australia observed 39 mostly female gray reef sharks (Carcharhinus amblyrhynchos) living near coral reefs in Palau, Micronesia, east of the Philippines.
In the winter, the sharks stayed closer to the surface, at an average depth of 115 ft (35 m), where water was consistently warmer, the team found. Meanwhile, the sharks plunged deeper when seasonal temperatures started rising in the spring, averaging depths of 200 ft (60 m).
The sharks also changed their behavior in sync with the lunar cycle, diving deeper during the full moon but sticking to the shallows with the new moon. Previous tagging studies showed that other open-water predators — including swordfish, yellowfin and big eye tuna — also go to greater depths as the lunar cycle progresses. This suggests the moon’s brightness might sway the movements of many big fish…
(read more: Live Science) (photo: P. Ayotte)
World’s Best Marine Sanctuary - Cabo Pulmo: Fish Increses
The effects of the reserve were not immediately apparent. In 1999, a survey showed mean fish biomass in the area was not statistically different from that in open-access fishing waters elsewhere in the Gulf of California. Ten years later, the situation in much of the gulf remained the same. In Cabo Pulmo, however, it had all changed; there had been a huge increase in fishes. As detailed in a paper due out in the online journal PLoS One on August 12, the increases were across all trophic levels, and led to a fourfold increase in biomass across the board.
Indeed, at 4.2 tonnes per hectare, fish biomass in Cabo Pulmo may constitute the highest recovery of any marine reserve in the world. The density of some species, such as these Devil Rays, is now sometimes so great that even from the air their density is overwhelming. “You can’t even really see from this photograph, but these rays are four or five deep in places,” says Grant Galland of Scripps Institution of Oceanography, who is a co-author of the PLoS One paper. “You couldn’t possibly get any kind of accurate count from underwater.”…
(read more: http://news.discovery.com/animals/endangered-species/most-successful-marine-reserve-cabo-pulmo-110812.htm)
photos by Octavio Aburto
Help Save the World’s Best Marine Reserve: Cabo Pulmo
Established in 1995, Mexico’s Cabo Pulmo Marine National Park is slightly more than 7,000 hectares of coastal waters in the Gulf of California, offshore from the small village of Cabo Pulmo. The park’s establishment followed a period of determined lobbying by the village’s 100 or so residents, who had become alarmed at overfishing and declines in the area’s marine life. The reserve is no more than 5 kilometers (3 miles) wide and measures just 14 kilometers (almost 9 miles) north to south. And yet its impact on the marine life within it, such as these Devil Rays, has been profound – so much so that researchers have dubbed it “the most successful marine reserve in the world.”…
(read more: http://news.discovery.com/animals/endangered-species/most-successful-marine-reserve-cabo-pulmo-110812.htm)
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What Can You Do to Help?
You can help save one of the oldest living coral reefs in the world with a click of your mouse: http://bit.ly/178KBhG
For 20,000 years, the reef of Cabo Pulmo has provided sanctuary for whale sharks, Pacific manta rays, humpback whales, dolphins and sea turtles, but today this marine reserve and the thriving sea that surrounds it is still under threat from overdevelopment.
Urge North America’s environmental authorities to support strong enforcement and protect the coral reef. Send your message!
http://bit.ly/178KBhG
(Photo courtesy of of Octavio Aburto / iLCP)
Close Encounter: Swimming With Sharks
By Matt Jenkins, Nature Conservancy magazine Senior Editor
Twenty four hours after touching down on Palmyra Atoll — a profoundly remote spot 1,000 miles south of Hawaii, where the skies are rarely marred by even the contrail of a passing airliner — photographer Tim Calver and I were aboard the research boat Zenobia. That morning, a team of researchers had been catching Gray Reef Sharks and implanting tracking tags in them; now it was time for lunch. As Kydd Pollock steered the boat back to the research station, something in the distance caught his eye — a frothy eruption on the ocean’s surface, with a scrum of seabirds wheeling overhead…
(read more: The Nature Conservancy)
This two-headed bull shark fetus was recently found by a fisherman and described in a science journal.
Read more: National Geo
(Photo: C. M. Wagner et al)
This two-headed blue shark fetus was removed from its mother by fisherman Christopher Johnston in 2008, off the coast of Australia.
read more: National Geo
(Photograph by Christopher Johnston)
Angular Roughshark (Oxynotus centrina)
…is a species of rough shark found throughout the eastern Atlantic, from Norway all the way down to South Africa. Unlike other rough sharks this species has ridges over its eyes, these ridges extend to knobs which are covered with scales. Angular roughsharks are usually found on muddy or algal bottoms of continental shelves where they feed on invertebrates like molluscs and arthropods.
Phylogeny
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OMG LOOK AT THIS MOTHERFUCKER… I love him so ;_;
Great White Sharks Gorge Together on Dead Whale Blubber
by Becky Oskin
Great white sharks feast together on dead whales, which are important food resources for the normally solitary predators, a new study finds.
Drawn by wind-blown slicks of chemicals from decomposing flesh, great white sharks measuring up to 16 feet (5 meters) long gathered at floating carcasses near South Africa’s Seal Island, gorging on blubber, researchers found during observing trips in 2000-2010. These giant sharks rarely appear near the coast but may cruise nearby, waiting to pounce on dead or dying whales, the researchers said.
“These massive sharks come in pretty quickly — within less than 24 hours,” of a dead whale’s arrival, said study co-author Neil Hammerschlag, a marine ecologist at the University of Miami. “We hypothesize these animals are cruising the coastline to take advantage of these types of situations.”…
(read more: Live Science)
Mobula Ray (Mobula sp.)
Photograph by Ralph Lee Hopkins, National Geographic
This photo was originally labelled as a “Manta Ray”, but these leaping rays are in fact closely related Mobula rays. They are most famous for their habit of leaping far out of the water off the Pacific coast of Mexico.
(via: National Geo)
