Sharks

Ameena · 102241. Wed Oct 11, 2006 5:41 pm

Hrrmm, Swot, he was referring to the quote he just made, wherein the original typo can be found ;).

samivel · 102693. Fri Oct 13, 2006 3:27 am

Old giffers? Pah!

Where's me Werther's?

swot · 103058. Sat Oct 14, 2006 10:07 am

Oh right. Sorry Southpaw. I wasn't paying enough attention.

Southpaw · 103570. Mon Oct 16, 2006 6:34 am

I should think so too. Humph.

By the ancient laws of QI, I now require a doughnut before I will talk to you again.

inca_drum · 108792. Sun Oct 29, 2006 3:48 pm

i got a shark fact for you thats not much well known -
Great Whites', despite the reputation and all the footage, dont even attack seals until they are at least 10 years old. Up until that age they live on fish and whatever they can scavenge. I suppose footage of a shark attack on a sardine isnt that thrilling!

Not a Number · 115954. Mon Nov 13, 2006 12:12 am

Shark vs. Octopus

Who do you think would win? You might find this video surprising (needs Realplayer)

http://www.pbs.org/wnet/nature/octopus/media_players_blue/shark_hi.html

bighairyfarrier · 144832. Fri Feb 09, 2007 2:19 pm

As far as I know the 'Meglodon' or lat, Carcharodon megalodon was the largest predetory fish ever to live, and was of the same family as the great white only much larger.

HasBeany · 151408. Sun Feb 25, 2007 5:56 pm

Shock Horror!
According to this evening's Natural World, the lovely Mr Attenborough stated that the ragged tooth shark [also called sandtiger shark] was the only species which evinces intra-uterine cannibalism. But when I trawled the net [what an appropriate phrase] ... I found this:

Quote from: http://www.elasmo-research.org/education/topics/lh_intrauterine_cannibalism.htm

Two forms of within-the-womb cannibalism are known in sharks. The most extreme form of intrauterine cannibalism - in which the largest and strongest embryo actually consumes its lesser womb-mates - is termed "embryophagy" or, more colorfully, "adelphophagy" - literally "eating one's brother". It was discovered accidentally in 1948, when a researcher probing the uteri of a late-term Sandtiger Shark (Carcharias taurus) was startled by a bite on the hand. To date, adelphophagy is known only in the Sandtiger. The less extreme and by far more common form of intrauterine cannibalism - in which developing embryos feed on a steady supply of tiny, unfertilized eggs - is termed "oophagy" (sometimes called "oviphagy") - meaning "egg-eating". The earliest documented case of oophagy dates back to 1907, in the Porbeagle (Lamna nasus). Both forms of intrauterine cannibalism continue throughout embryonic and fetal development, so that at birth each pups often has aa conspicuously swollen abdomen known as a "yolk stomach".

Until quite recently, intrauterine cannibalism was thought to be restricted to lamnoid sharks. This grisly form of within-the-womb nutrition is now known from two carcharhinoids and even one orectoloboid. Following is a list of all sharks in which intrauterine cannibalism has been documented, or for which exists strong circumstantial evidence:

Order Orectolobiformes

Family Ginglymostomatidae

Tawny Nurse Shark (Nebrius ferrigineus)

Order Lamniformes

Family Carchariidae

Sandtiger Shark (Carcharias taurus)

Family Pseudocarchariidae

Crocodile Shark (Pseudocarcharias kamoharai)

Family Alopiidae

Pelagic Thresher Shark (Alopias pelagicus)
Bigeye Thresher Shark (Alopias suprciliosus)
Common Thresher Shark (Alopias vulpinus)

Family Cetorhinidae

Basking Shark (Cetorhinus maximus)

Family Lamnidae

Salmon Shark (Lamna ditropis)
Porbeagle (Lamna nasus)
White Shark (Carcharodon carcharias)
Shortfin Mako (Isurus oxyrinchus)
Longfin Mako (Isurus paucus)

Order Carcharhiniformes

Family Pseudotriakidae

Slender Smoothhound Shark (Gollum attenuatus)
False Catshark (Pseudotriakis microdon)

Well I never!!!!

Mulvil · 151553. Mon Feb 26, 2007 8:39 am

The Bull Shark is the only shark that can tolerate both freshwater and seawater and bull sharks have been found as far upstream as baghdad in iraq.

They stay in shallow coastal waters as well as being found in rivers and lakes.

It is thought that many of the attacks on humans that are attributed to great whites are in fact the work of bull sharks which are, as previously stated, fond of shallow coastal waters, river mouths, bays, rivers and lakes, where humans may be found swimming.

They are also often called the Zambezi shark, the Ganges sharks and the Nicaragua shark.

Mulvil · 203419. Thu Aug 23, 2007 5:30 pm

And then there is the parthenogenesis that has recently been observed in Hammerhead sharks.

That is to say there has been a virgin birth. A shark in a zoo gave birth in 2001 with no apparent contact with a male. And just to prove there was no accidental contact the pup was DNA tested and ONLY maternal DNA was found.

I'm sure a lot of you already knew this and I've been meaning to post it for a while.

http://news.bbc.co.uk/2/hi/science/nature/6681793.stm

Also recently watching a documentary I saw the host standing in a shallow pool of water with a behavioural expert, surrounded by Bull sharks. I was thinking "well thats stupid, bull sharks are extremely unpredictable".

Anyway the expert said something along the lines of "if we just stand here they'll recognise we're not a threat and the won't attack us" (or something to that affect). One large female then proceded to remove the calf of his leg.

Anyone else enjoying shark week on discovery?

k.bygrave · 224051. Fri Oct 26, 2007 9:42 am

[quote="Mulvil"]They are also often called the Zambezi shark, the Ganges sharks and the Nicaragua shark.

Bull sharks are notorious in the Ganges, as people traditionally float thier dead relatives down the Ganges, with obvious benefits to the sharks

k.bygrave · 224060. Fri Oct 26, 2007 9:51 am

[quote="Hans Mof"]Only four species of shark are known to fatally attack humans: great white, bull shark, tiger, oceanic whitetip.

Interesting fact about oceanic white tips - they are usually the first species present when boats are sinking or planes have crashed over water and this is why they are considered dangerous to humans.

longwing · 778465. Fri Jan 21, 2011 12:14 pm

I learnt today during my self-teach course that shark skin used to be sold to use as sandpaper. I felt a piece - certainly when dried it would make good sandpaper and it has different grades depending on wherabouts on the shark you get it from. The scales are very hard, bony and sharp. They come in a range of sizes from minute to rather large.

Jenny · 778471. Fri Jan 21, 2011 12:48 pm

Shark skin is also used to make a kind of leather called shagreen, though they grind down the rougher bits for that.

Welcome longwing :-)