Impurest's Guide to Animals #26 - Daggernose Shark

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ImpurestCheese

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Edited By ImpurestCheese

Issue 26, ah blessed 26. But why is this issue so special? Well not only is it Shark Week (apparently) but it is also half a year since a rather unassuming blog appeared on the off-topic page, in other words this one. As such I would like to say a big thank-you to everyone and anyone who has ever read and commented on this series.

Many Thanks

Impurest Cheese

_____________________________________________________________________

Issue #26 - Daggernose Shark

[1]
[1]

Kingdom – Animalia

Phylum – Chordata

Class – Chondrichthyes

Order – Carcharhiniformes

Family – Carcharhinidae

Genus – Isogomorphodon

Species – oxyrhyncus

Related Species - Daggernose Sharks are a member of the Requiem Shark Family which includes the Tiger Shark (Galeocerdo cuvier) (1)

Range

[2]
[2]

Murky Waters

The Daggernose Shark is a small shark that grows up to a meter and a half in length and around thirteen kilos in weight. Like other Requiem Sharks, the Daggernose has a streamlined body designed for short bursts of speed rather than prolonged high speed chases. In addition the Daggernose has a more pronounced, almost blade like snout that is packed with additional electro-sensitive receptors to aid in navigation and prey detection in muddy waters. Due to it’s preference for muddy waters the eyes of the Daggernose are smaller than sharks of a similar size found elsewhere in the world (2).

The Daggernose hunts on small fish, often making runs into shoals of fish to injure its targets, before coming back around to finish them off, with an extendable pair of jaws and rows of small needle like teeth. Adult Daggernose Sharks are outside the size range of other coastal predators although the young are prey to both the Bonnethead (Sphyrna tiburo) and the Smalltail Shark (Carcharhinus porosus). Despite being a coastal species the Daggernose is intolerant to large quantities of fresh-water and during the Wet Season, moves away from river mouths and mangrove forests.

[3]
[3]

Despite being harmless to humans, the Daggernose shark is still hunted in some parts of its range. Gillnetting in particular, is dangerous to the Daggernose and it makes up one tenth of the bycatch found in North Brazilian fisheries. Official records show a ninety percent decline in the last decade due to overfishing and a slow reproductive rate with the ICUN classifying the species as Critically Endangered (3).

Conservation Crisis: Five to Save #2 - Cartilaginous Fish

Imagine the scene, the oceans deadliest predator is on the prowl, scanning the surface of the water waiting until, prey in range it strikes before dragging the victim up to a slow and cruel fate. But this creature is no giant predatory shark but rather Mankind and its voracious hunt for more and more resources. Being competition for the sea’s bounty it’s no surprise Sharks and Rays (as well as their close allies the Sawfish and Guitarfish) are some of the most endangered animals on the planet. In fact it’s estimated that 1 in 4 species of Shark and Ray are either listed as Vulnerable or Endangered. As such the list was expansive so I chose five that highlighted different threats faced by these majestic ocean masters. (4)

Angel Shark (Squatina squatina) - Critically Endangered

Threats - Commercial Fishing: Large scale fishing operations of the Angel Shark or Monkfish are nothing new but recently fish stocks have been declining rapidly. Coupled with low reproduction rates the Angel Shark is extinct in some parts of its range although efforts by UK Government to preserve the species, within its waters, have had some limited success

Common Guitarfish (Rhinobatus rhinobatus) - Endangered

Threats - Fin Fishing: Due to it’s placid nature and because it inhabits shallow water the Common Guitarfish is an easy target for shark fin fishing expeditions. During 1994 and 1999 the species was declared extinct in its Northern Part of its range despite an overwhelming abundance just fifty years previously.

[4]
[4]

Ganges River Shark (Glyphis gangeticus) - Critically Endangered

Threats - Pollution: As one of six freshwater sharks, the Ganges Shark faces problems with acute industrial pollution and river dams not found in oceanic species. In addition the species is unjustly persecuted due to misidentification with the Bull Shark (Carcharhinus leucas)

Giant Devil Ray (Mobula mobular) - Endangered

Threats - Bycatch: The only species of Manta Ray found in British Waters suffers from accidental persecution from commercial fisheries. Devil Rays often get caught in nets and lines set for smaller fish and eventually exhaust themselves after fighting to free themselves for hours, maybe even days before dying. Captured specimens are often thrown back since there is no commercial value in the species.

Giant Freshwater Stingray (Himantura polylepis) - Endangered

Threats - Sport Fishing: Adult Giant Stingrays are a prized sport fish, due to their size and tenacity when hooked. Unfortunately the species is often damaged after being hooked and, since there is no commercial value for the species, often returned to die a slow agonising death in the river. The Thai Government is, at current, maintaining a captive bred population but wild release has not yet been scheduled.

Bibliography

1 - www.arkive.org

2 - Fowler, S.L., R.D. Cavanagh, M. Camhi, G.H. Burgess, G.M. Cailliet, S.V. Fordham, C.A. Simpfendorfer, and J.A. Musick (2005). Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes. International Union for Conservation of Nature and Natural Resources. pp. 306–30

3 - Lessa, R., F.M. Santana, V. Batista and Z. Almeida (2000). "Age and growth of the daggernose shark, Isogomphodon oxyrhynchus, from northern Brazil". Marine and Freshwater Research51 (4): 339–347.

4 - http://www.iucnredlist.org/

Picture References

1 - http://38.media.tumblr.com/tumblr_m8tdayXqT41qc6j5yo1_500.jpg

2 - http://upload.wikimedia.org/wikipedia/commons/3/3f/Isogomphodon_oxyrhynchus_distmap.png

3 - http://shark-references.com/images/species/600xNxIsogomphodon_oxyrhynchus,28MUELLER,aHENLE,,1838,29.jpg.pagespeed.ic.ptL484NyS4.jpg

4 - http://upload.wikimedia.org/wikipedia/commons/0/07/Rhinobatos_Rhinobatos.jpg

Thanks for reading guys; I hope you enjoyed the exploration into the daunting future of the Daggernose Shark. For the next few weeks we have requests from @laflux, @scorpion2501 and @darthaznable, but as usual drop off some comments and check out past issues in Impurest’s Bestiary.

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Cream_God

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#2  Edited By Cream_God

Why are there none in the Gulf of Mexico?

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deactivated-5c901e667a76c

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#3  Edited By deactivated-5c901e667a76c  Moderator

It's sad that they're all endangered.

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ImpurestCheese

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@cgoodness: The water in the Gulf is too cold, too deep (in general) and not muddy enough

@xwraith: Very sad indeed

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Straight-Fire

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I'm not receiving notifications at all. -_-

It's here!! I've been waiting for the longest. xD This is very interesting! You always amaze me. Keep up the good work. ^_^

I feel bad for the endangered sharks. D:

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ImpurestCheese

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@dboyrules2011: Notifications are down for everyone. Sorry about the wait but ecological surveying can't be rushed, so everything else has to go on hold. Thanks for the comment nevertheless

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Straight-Fire

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@impurestcheese: I was just playing. :) I apologize if I sounded like a fool. You're welcome.

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Ostyo

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@impurestcheese: Woo! I love all things shark related. Thank you once again, Big Red.

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ImpurestCheese

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@ostyo: Big Red, wow now you're digging me because of my height as well :-D

@dboyrules2011: - Nah it's cool

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Straight-Fire

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#11  Edited By ImpurestCheese
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dngn4774

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wildvine

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@impurestcheese:

I literally just read this. ^_^

Really sad for all those poor things. I hate sport fishing/hunting. If they were being eaten or something it would be different.

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ImpurestCheese

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@dngn4774: Yeah the Common Guitarfish is wondering where everyone north of Senegal has gone

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deactivated-5a162dd41dd64

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From the side it kind of almost looks like a goblin shark...

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ImpurestCheese

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@wildvine: Don't sweat about the late comment, notifications have been down for everyone. As for shark fishing well it wouldn't be fine, regular subsistence fishing is virtually extinct. Commercial fishing takes things too far too fast, or at least that's my opinion.

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dngn4774

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@wildvine: ah humans...the greatest d**ch*b*gs of the animal kingdom.

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ImpurestCheese

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@squares: Good Observation. Both species live in low visibility water and rely on smell and electro receptors on the rostrum to navigate. Hence why the two species look the same

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Uncanny_XFactor

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This is really cool, and I hate to ask this, but (what's the connection to comics?)

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laflux

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@wildvine said:

@impurestcheese:

I literally just read this. ^_^

Also when is my nemesis bird that drove me bonkers is coming up. Or did I not see that because of notifications too?

Sharks are interesting, thanks as always. One question, do Freshwater Estuarine sharks still use TMAO in homoeostasis? Or is that only restricted to Marine sharks?

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ImpurestCheese

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@uncanny_xfactor: Absolutely nothing. I work as an ecologist however, and over six years of surveys and translocations have found and learnt about some amazing creatures. As such I pass on said learning in a weekly segment.

@laflux: It's been pushed back due to requests. Freshwater Rays and Sharks either reduce the production of urea and TMAO or stop it entirely.

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Uncanny_XFactor

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Ah, that's quite cool.

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DarthAznable

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@impurestcheese Yooo. This is one of my favorite sharks. Thanks for doing this one.

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Ostyo

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@impurestcheese: Tall girls are the best. ;D Lol So any clues on the next animal?

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scattered316

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Tis a shame the angel shark and co are currently in danger, I remember seeing them on documentaries when I was little, popping out of the sand....

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Samimista

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@impurestcheese: Ah wow, congrats on the half year, dearie! <3 You dedicate so much effort and time into these blogs. Always look forward to reading them. =)

I never heard of a daggernose shark before but they look really cool! xD

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ImpurestCheese

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@darthaznable You're welcome. As sharks go it's highly illusive (no photos), highly endangered (damm you commercial fishing) and awesome to boot

@uncanny_xfactor Thanks I try

@ostyo: Ask Laflux ;-)

@scattered316: Yep, but unfortunately they (apparently) taste too good to be left alone

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Ostyo

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@laflux: Big Red says you know about next week's animal?

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laflux

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#30  Edited By laflux

@ostyo: Is that what you call Impurestcheese? How sweet :p

Probably the Patas monkey then.

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Ostyo

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#31  Edited By Ostyo

@laflux: Well, she's a sweet woman. :P

Oh snap, dawn of the Apes time!

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deactivated-097092725

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You would think the high levels of mercury in shark meat would make a difference to those who fish them for food purposes. Then again, the market for shark fins is a booming business. Great article and thank you for bringing attention to the plight of these poor animals.

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ImpurestCheese

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@ms-lola: Thanks, you would think the pisons would be a deterrent but apparently not