All types of sharks are cartilaginous fish. That is to say they don't have a bone in their body. Cartilage yes, but real bone no. Along with skates and rays, their skeleton is made of cartilage.
Another shared characteristic with skates and rays is the absence of a swim bladder, which means that if they don't want to sink like a stone they need to keep swimming.
Many types of sharks are under threat of extension, largely due to the world's (and in particular China's) increasing appetite for sharks' fin soup.
The appalling practise by commercial shark fishermen of cutting off the fins and throwing the rest of the fish - still alive - back into the sea is not just unsustainable, it's downright revolting.
Shark are distinctly uncuddly creatures and, being often on the receiving end of bad press internationally, this somehow seems to make such treatment acceptable.
OK, personal rant over, let's take a look at the the most common types of sharks that cruise around in the Atlantic Ocean.
All artwork by Keith Linsell
The Blue Shark is the most plentiful of all types of sharks that frequent the Atlantic waters of Britain and Northern Europe during the summer months.
In warmer seas it is said to grow up to 20 feet, but hereabouts their average weight is around 30lb to 50lb. Even so, the British record is an excellent specimen caught off Looe in Cornwall, which tipped the scales at 218lb.
It's a beautiful fish, long and slender with a dark indigo back, bright blue flanks and a pure white underside.
The Porbeagle Shark is much more tolerant of cold water than the Blue Shark. In fact the British record fish of 507lb was caught off Dunnet Head in the far north of Scotland.
They are known to venture close inshore in some parts, but they're more frequently found tide races, reefs and rocky outcrops - especially if deep water is close by.
Porbeagle Shark will eat almost any fish that swims, but herring and mackerel are probably at the top of its hit list.
For many shark anglers, the Mako is the king of sharks. Hook one of these and you've got a real battle on your hands. A Mako Shark has much more power and stamina than a Blue or Porbeagle of similar size, and will to spectacular heights in its attempt to regain its freedom.
They're a true pelagic fish of the open ocean, where they feed predominantly on mackerel, bonito and herring in the upper levels. Mako Shark grow to a huge size - the world record being over 1,000lb - and are ferocious predators. Distinctly uncuddly and definitely not one to go swimming with!
In appearance they closely resemble a large Porbeagle, but there are some key differences:~
Another very rare visitor to British waters - so much so that no Hammerhead Shark have yet been caught here on rod and line.
So the British record is up for grabs - catch just one Hammerhead and it's yours!
But you'd have to go some to beat the one caught off Florida in 2006 - over 14 feet long and weighing in at 1,262lbs. A huge fish, with a head 3 feet wide.
Hammerhead Sharks are unmistakable of course, with their laterally flattened head and their eyes located in the end-plates.
A relative minnow by shark standards, the six-gilled shark is so named because - in a defiant gesture of oneupmanship - it has six gills along either side of its throat, rather than the standard shark set of five.
This is a bottom feeding shark, and is mostly caught accidentally by anglers fishing for skate and rays.
The British rod-caught record for these types of sharks currently stands at 9lb 8oz for a specimen caught off Penlee Point, Plymouth.
Another easily identified shark, this one incorporating a design modification at the other end in the form of an impressive extension to the upper tail lobe.
It's as long as the rest of the shark's torso, and is used to corral a shoal of mackerel or herring into an even tighter bunch.
Having done so, the Thresher Shark gives the terrified fish a sharp 'thwack' with his tail, then leisurely proceeds to dine on the casualties. Clever.
Another large shark, approaching a maximum weight of 1,000lb or more. The current British rod-caught record Thresher Shark weighing 323lb was caught near the Nab Tower off Portsmouth.
In the USA
In the UK
Downrigger ~ The cranelike device incorporating a line-counter reel often seen on the sterns of sport-fishing boats, which lowers a trolling weight on a wire line to a pre-determined depth. The trolling line is attached just above the weight, which gets the lure down to depths that would otherwise be unachievable.