sawshark

Japanese Sawshark (Pristiophorus japonicus)

…a species of sawshark (Pristiophoridae) which occurs in the northwest Pacific Ocean around Japan, Korea, and northern China, where it inhabits the sandy or muddy bottoms of the continental shelves (at depths of 50-800 m). Japanese sawsharks are primarily “benthic” and will feed on a wide range of small bottom dwelling invertebrates and fish. 

Classification

Animalia-Chordata-Chondrichthyes-Elasmobranchii-Pristiophoriformes-Pristiophoridae-Pristiophorus-P. japonicus

Image: Opencago.info

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Sawfish vs Sawshark

Sawfish (Family: Pristidae)

  • larger size (<20 ft.)
  • pectorals attached to side of head
  • blade like teeth same size
  • gill slits are ventral
  • no barbels
  • prefer shallow waters

Sawshark (Family: Pristiophoridae)

  • smaller size (<5 ft.)
  • pectoral fins not attached to side of head
  • blade like teeth alternate in size 
  • gill slits are ventrolateral 
  • barbels present
  • deep-water inhabitants 

Sawfish (Family Pristidae) and Sawsharks (Family Pristiophoridae) are commonly mistaken for each other. It’s pretty easy to do that, since they’re both really unique predators built for a gnarly kill with their intense saws for teeth. They’re both elasmobranchs, making them distantly related. The sawshark is, you guessed it, a shark! The sawfish, on the other hand, is a ray. Sawsharks also have two barbels that stick out in the middle of their saws, resembling whiskers, and happen to work like that of a catfish. They feel along the ocean floor for any potential prey, which is something saw fish can’t do. Also, sawfish have gill slits on their undersides like a typical ray, whereas sawsharks have gill slits on their side like a shark. Makes sense, eh? Saw sharks have alternating teeth sizes, making them look a bit more unkempt, whereas sawfish have a nice polished look with evenly sized teeth all around. This sucks for the tidy sawfish though, since unlike that unorganized sawshark, his teeth don’t grow back. It’s cool though, since they’re bigger than sawsharks. Measuring in from 1.4 m (4.6 ft) to 7 m (23 ft), sawsharks can barely compare at up to 1.7 m (5.6 ft) long. 

SawsharkPristiophoriformes

“There are seven known species of sawsharks (Pristiophoriformes) that have long snouts with teeth, but they are not related to sawfish (although sawsharks are fish). They swim along the floor of the ocean and use their snouts exactly as you would imagine: they smack their prey sideways to disable them. Sawsharks eat squid, crustaceans, and small fish. They look much more dangerous than they are.”   -

(by Leopold Wilson)

The African Dwarf shark (Pristiophorus nancyae) - one of four new shark species found in 2011.

Christine Dell'Amore

National Geographic News

The African dwarf sawshark (Pristiophorus nancyae) was accidentally captured in a 1,600-foot-deep (490-meter-deep) trawl off Mozambique. The animal is only the seventh species of sawshark known to science, according to David Ebert, a research associate at the Academy.

The predator has a long, tooth-studded snout that it uses like a sword, whipping the appendage through schools of fish and then returning to eat any casualties.

Along with the sawshark, a new species of angel shark, Squatina caillieti, was named from a single specimen collected in 1,200-foot-deep (370-meter-deep) water off the Philippine island of Luzon, Ebert said.

Bottom-dwelling angel sharks, whose large pectoral fins resemble wings, lie partially buried in sediment and ambush passing prey.

In addition, two species of lanternshark in the Etmopterus genus were also discovered in Taiwan and South Africa, respectively.

The discoveries are part of a recent boom in new shark and ray finds. Over the past decade, about 200 new species have been described, compared with fewer than 200 in the previous three decades, Ebert said.

Despite these advances in describing new sharks, scientists know very little about the predators’ behaviors or their populations, he added.

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Rules:

  • Reblog this thingy
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          me 

          sawshark

          idiotbrunette

          accldent

          boodicolo

          creppyvampire

          lnalloweentown

          okaydad2013

          spookyselfiepolice

Thats it! We will pick the winners on Wednesday, October 30 to be promo’d! Good luck to everyone!!!!!!

Bahamas Sawshark

The Bahamas sawshark (Pristiophorus schroederi) belongs to the family Pristiophoridae. In contrast to its Asian “congener” (that’s scientist-speak for member of the same genus) that we recently featured - the Pacific-dwelling Japanese sawshark (P. japonicus) - this species lives in the Atlantic Ocean. It is also known as the American Sawshark.

The distinctive snouts of these sharks are long, flat, and tapered. They have the appearance of sporting a thin, cheesy moustache: really, the whisker-looking barbelsare fleshy appendages thought to aid in feeding. Sawsharks have numerous serrated teeth on either side of the snout (hence their common name). Adults grow to be at least 80 cm (31") long.

Bahamas Sawshark Facts

This fish is a poorly known tropical sawshark that prefers deep water. It is endemic to the Bahamas region, and is known from only a limited number of specimens.

It has 13 or 14 teeth on each side of the snout in front of the barbels, and then another 9 to 10 on each side behind the barbels. That means it might have a total of about 48 teeth, giving the snout (“rostrum”) its unmistakable saw-like appearance.

Habitat and Range

The geographic distribution of this species is a narrow range within the Western Central Atlantic, between Cuba, Florida and the Bahamas. This shark prefers to stay on or near the bottom at depths between 400 to 1,000 m (1330 to 3330 ft).

Basically nothing is known about its population(s), which is thought to be isolated by deeper waters that represent unsuitable habitat. The known range is restricted to the continental and insular slopes around the Bahamas: the sawshark has never been recorded on the adjacent North American continental slope, and so it is presumed absent from that area.

Feeding Behavior

Nothing is known about the diet of this species. Based on the feeding ecology of other sawsharks, this creature like eats small fish and invertebrates that live on the ocean bottom. Both the tapered snout and the sensitive barbels are adaptations that could help with finding prey items buried in sand and mud on the sea floor.

Breeding

The Bahamas sawshark is presumed to be ovoviviparous, meaning that the young are sustained inside the mother with an aplacental yolksac. Pups measure 30 cm (11.8") long at birth.

Nothing else is known about the life history parameters of this species.

Humans and Conservation

This is a harmless shark, from the perspective of humans that is (shrimps and tiny fish might beg to differ!).

No fisheries are known to be presently targeting this species.

The IUCN Red List deems the Bahamas sawshark to be “Data Deficient” - that is, a proper assessment is not yet possible because so little is known about its basic biology, and the full distribution is poorly defined.There is a need for population surveys and more information about the activities of any fisheries within the range of this shark. Any future deepwater activities in the area need to be carefully monitored; the narrow range of the species means that it could be particularly vulnerable to disruption of its habitat.One country that seemed to have taken some conservation action regarding this species is Mexico. In response to urging by the United Nations General Assembly, Mexico is one of only a handful of the top 20 shark-catching nations (along with Taiwan, the US and Japan - as of 2007) to have adopted a “National Action Plan for Shark Conservation”. The Mexican plan was approved in 2004; it assessed Pristiophorus schroederi as being endangered or threatened and thus worthy of protection. However, to the best of our knowledge this plan has not been implemented. In other words, the policy has not translated into any formal protection of the species in Mexican waters.