Bizarre, Prehistoric Ratfish Chomped Prey with Buzzsaw Jaws
by Brian Switek 
Helicoprion had saws for jaws. That’s really all there was to the 270 million year old ratfish’s dental cutlery. No upper teeth or anything else to slice against – just an ever-growing whorl of spiky teeth anchored to the lower jaw.
This new, definitive image of Helicoprion debuted last year thanks to the efforts of artist Ray Troll and a team of researchers led by Idaho State University paleontologist Leif Tapanila. A very special fossil – IMNH 37899 – preserved both the upper and lower jaws in a closed position, finally solving the mystery of what the ratfish’s head actually looked like. But determining the exact placement of that vexing spiral was just an initial step.
Paleontologists and artists had often supposed that Helicoprion had upper teeth to pierce slippery cephalopods and squirming fish, but the fossils Tapanila and colleagues examined showed that Helicoprion only had a buzzsaw embedded in the lower jaw. How did this long-lived and prolific genus of Permian fish eat with a saw for a jaw? …
(read more: Laelaps blog - National Geographic)
photograph by Brian Switek

Bizarre, Prehistoric Ratfish Chomped Prey with Buzzsaw Jaws

by Brian Switek 

Helicoprion had saws for jaws. That’s really all there was to the 270 million year old ratfish’s dental cutlery. No upper teeth or anything else to slice against – just an ever-growing whorl of spiky teeth anchored to the lower jaw.

This new, definitive image of Helicoprion debuted last year thanks to the efforts of artist Ray Troll and a team of researchers led by Idaho State University paleontologist Leif Tapanila. A very special fossil – IMNH 37899 – preserved both the upper and lower jaws in a closed position, finally solving the mystery of what the ratfish’s head actually looked like. But determining the exact placement of that vexing spiral was just an initial step.

Paleontologists and artists had often supposed that Helicoprion had upper teeth to pierce slippery cephalopods and squirming fish, but the fossils Tapanila and colleagues examined showed that Helicoprion only had a buzzsaw embedded in the lower jaw. How did this long-lived and prolific genus of Permian fish eat with a saw for a jaw? …

(read more: Laelaps blog - National Geographic)

photograph by Brian Switek

Sawfish Science in Florida
This just in — NOAA Fisheries Biologists Dr. John Carlson, Dana Bethea, Grace Casselbury and intern Ryan Jones are on their monthly expedition examining the distribution and abundance of smalltooth sawfish (Pristis pectinata), an ESA endangered species, in Everglades National Park. 
The scientists have recorded some extremely low salinity measurements this expedition and are measuring how the distribution of sawfish changes in response to low salinity. Today they tagged a 3 ft female near Chokoloskee Island. All of this research is designed to help implement recovery objectives in the ESA. 
Photo credit: Ryan Jones 
Check out our video on how we protect them: 
Protecting an Endangered Species:  Smalltooth Sawfish
(via: NOAA Fisheries)

Sawfish Science in Florida

This just in — NOAA Fisheries Biologists Dr. John Carlson, Dana Bethea, Grace Casselbury and intern Ryan Jones are on their monthly expedition examining the distribution and abundance of smalltooth sawfish (Pristis pectinata), an ESA endangered species, in Everglades National Park.

The scientists have recorded some extremely low salinity measurements this expedition and are measuring how the distribution of sawfish changes in response to low salinity. Today they tagged a 3 ft female near Chokoloskee Island. All of this research is designed to help implement recovery objectives in the ESA.

Photo credit: Ryan Jones

Check out our video on how we protect them:

Protecting an Endangered Species:  Smalltooth Sawfish

(via: NOAA Fisheries)

dendroica

seascienceweekly:   Plankton Eating Sharks

Lets start off with the not-so-much meat eating sharks.

Well, kinda, the Whale Shark (middle) still eats krill, and we don’t really know much about the Megamouth Shark (bottom), but it probably eats Jellyfish and other sorts of plankton. Either way, with the Basking Shark (top), these three sharks make up the filter feeding, planktivorous sharks.

They swim with their massive mouths open through the water and filter out all the tiny particles for food. Even though they have similar methods of feeding they’re actually quite different!

Whale sharks fall under the taxanomic classification of Orectolobiformes (or carpet sharks), similar to Nurse Sharks, while Megamouths and Basking Sharks fall under Lamniformes (Mackerel Sharks) like great whites.

Both Whale Sharks and Basking Sharks are classified as vulnerable by the IUCN, where as the Megamouth Shark is so rare  that we can’t really say - only 3 Megamouths have ever been recorded on film!

Whale Sharks are absolutely incredible animals, they can grow to 10 meters, weigh 10 tonnes and live to 70 years, while Basking Sharks are slightly smaller at 8 meters and 5 tonnes.

They might all look a bit scary, but are completely and absolutely harmless to humans, the only thing they’d hurt is krill!

The Whale Shark (Rhincodon typus) 
… is the largest living species of fish, with individuals reaching lengths of 41 feet (12.5 m) or more. Though fearsome in size, Whale Sharks are gentle giants. They feed on plankton and small fish, and are generally quite tame and docile around divers. 
Unlike dolphins and whales, which give birth to a single large baby, Whale Sharks are ovoviviparous - they produce up to a few hundred eggs, which the mother incubates within her body. They are fertilized slowly using stored sperm, and babies are birthed with regularity rather than in one large event. When born, young Whale Sharks are dwarfed by their mother, measuring only 16 to 24 inches (40 to 60 cm) long. Individuals take a long time to reach sexual maturity, first starting to breed around 30 years old, but may live to ages of 70 or more years. 
They inhabit tropical and sub-tropical oceans worldwide; on North America’s coasts, they are primarily found off California in the Pacific, and sometimes as far north as New York in the Atlantic.
photo by Zac Wolf, borrowed from Wikimedia
(via: Peterson Field Guides)

The Whale Shark (Rhincodon typus)

… is the largest living species of fish, with individuals reaching lengths of 41 feet (12.5 m) or more. Though fearsome in size, Whale Sharks are gentle giants. They feed on plankton and small fish, and are generally quite tame and docile around divers.

Unlike dolphins and whales, which give birth to a single large baby, Whale Sharks are ovoviviparous - they produce up to a few hundred eggs, which the mother incubates within her body. They are fertilized slowly using stored sperm, and babies are birthed with regularity rather than in one large event. When born, young Whale Sharks are dwarfed by their mother, measuring only 16 to 24 inches (40 to 60 cm) long. Individuals take a long time to reach sexual maturity, first starting to breed around 30 years old, but may live to ages of 70 or more years.

They inhabit tropical and sub-tropical oceans worldwide; on North America’s coasts, they are primarily found off California in the Pacific, and sometimes as far north as New York in the Atlantic.

photo by Zac Wolf, borrowed from Wikimedia

(via: Peterson Field Guides)

Bizarre Blue Shark Nursery Found in the North Atlantic

Rather than emerging in protected coves, baby blue sharks spend their first years in a big patch of open ocean

by Rachel Nuwer

The scientists trapped 37 blue sharks ranging in age from young juveniles to adults and outfitted them with satellite transmitters. They released the sharks and then waited for the data to arrive. As months rolled into years, an interesting pattern emerged.
Within the first two years of life, the researchers report in the journal PLOS ONE, the sharks spent most of their time in a patch of the North Atlantic.
Most shark species establish nurseries in protected bays or other sheltering areas. The notion that blue sharks grow up completely out in the open suggests that protection from predators is not a motivating factor. But figuring out what advantages, if any, that particular spot provides will require further study…
images: Photos by Nuno Sa/Nature Picture Library/Corbis and Mark Conlin/NMFS, graphic from Vandeperre et al., PLOS ONE
lostbeasts

strangebiology:

Paleontologists found this sweet whorl of teeth called a Helicoprion, but really didn’t know how it might have been situated in a fish’s mouth. 

There were many theories postulated about how the teeth fit in the animal’s mouth (fourth image). When another specimen was found, it was determined that the owner of this strange jaw (not a shark, but a ratfish) had no upper teeth at all.

Ladies and gentlemen, the most metal fish.

(via Laelaps/National Geographic) Art by Ray Troll.

cool-critters

cool-critters:

Bowmouth guitarfish (Rhina ancylostoma)

The bowmouth guitarfish is a species of ray. This rare species occurs widely in the tropical coastal waters of the western Indo-Pacific.

This large species can reach a length of 2.7 m (8.9 ft). The jaws are heavily ridged with crushing teeth arranged in wave-like rows. Usually found near the sea floor, the bowmouth guitarfish prefers sandy or muddy areas near underwater structures.

It is a strong-swimming predator of bony fishes, crustaceans, and molluscs. This species gives live birth to litters of two to eleven pups, which are nourished during gestation by yolk. The International Union for Conservation of Nature (IUCN) has assessed the bowmouth guitarfish as Vulnerable because it is widely caught by artisanal and commercial fisheries for its valuable fins and meat.

The bowmouth guitarfish, often described as prehistoric in appearance, is considered by some scientists to be the ‘missing link’ between sharks and rays based on the ray-like placement of the mouth and gill openings, and disc shape of the front part of the body and the shark-like streamlined appearance of the rest of the body and the powerful tail.

photo credits:Brian Gratwicke, Jason Isley, planetearth, link

How Tiger Sharks Affect Shark Bay’s Eco-System

For the last two decades, Michael Heithaus has been studying how tiger sharks affect one particular ecosystem – Shark Bay, Australia, one of the world’s most pristine seagrass ecosystems. The Florida International University biologist explains how his team studies these top predators and their prey, and why tiger sharks are so important to the health of Shark Bay.

(via: National Science Foundation)

scientificillustration
alexa-rossi:

Helicoprion
I like prehistoric sharks a lot; they come in all kinds of weird shapes so you can re-imagine them as you like, practically. This one I like because the unusual whorl of teeth that even to this day hasn’t been properly placed within this shark’s anatomy.
This is my reconstruction of Helicoprion bessonovi.

alexa-rossi:

Helicoprion

I like prehistoric sharks a lot; they come in all kinds of weird shapes so you can re-imagine them as you like, practically. This one I like because the unusual whorl of teeth that even to this day hasn’t been properly placed within this shark’s anatomy.

This is my reconstruction of Helicoprion bessonovi.