Some of the great illustrations to come out of the HMS Challenger Expedition.

Seminal moments in marine science - the HMS Challenger Expedition

The HMS Challenger expedition between 1872 and 1876 is one of the key moments in marine science. An old navy ship modified for scientific research, HMS Challenger travelled all over the world completing experiments and collecting data.

360 stations on the ship collected all kinds of different measurements such as depth, temperature, weather and wind conditions as well as animal, sediment and water samples.

One of the most famous findings was the discovery of the Challenger Deep, measured to be around 8200 meters by the vessel, but now known to be in excess of 10000 meters deep.

After having spent 750 days at sea, the ship arrived back in Hampshire on the 24th of may 1876. The research collected would be published in 50 volumes over 19 years, and can all be read for free here!

Ernst Haeckel’s Kunstformen der Natur

Amongst 100 other prints, Ernst Haeckels Cnidaria drawings are some of my favourites. Shown above is discomedusae and anthomedusae cnidarians. 

Well, that’s shark week!

Regularly scheduled programming will continue tomorrow. 

Anybody have any requests?

The Great White

Alright, last post of shark week. I’ve gone all week without mentioning probably the most famous shark in the world, so here we go; the great white. 

One of the longest and heaviest cartilaginous fish out there (6 meters and over 1000 kg), it’s thought to live up to 70 years, swim 50 km/h and migrate all over the world. Evolution has rarely been so good to an animal. 

The only natural predator other than humans is the orca. Two incidents have been recorded where orca killing and eating great whites - both off the coast of California, once in 1997 and once in 2000. Interestingly, after these two killings local great white populations disappeared, as if they were fleeing. Researchers think that the smell of the great white carcass might be responsible for this.

Sadly a 2010 study estimated the total world population of great whites to only be 3500. 

Two of the lesser known species of hammerhead shark; the winghead shark (Eusphyra blochii) and the bonnethead shark (Sphyrna tiburo)

The hammerheads

Shark week may be over on Discovery channel but i’ve still got a couple of posts to go on here. 

Let’s talk about hammerhead sharks. There are actually 10 different species of hammerheads, all within the family Sphyrnidae, 1 species in the genus Eusphyra and the other 9 within Sphyrna. The largest of the 10 is the great hammerhead shark, which can grow up to 6 m and 600 kg.

Hammerhead sharks are really interesting for several reasons. Most obviously, the oddly shaped head is thought to enhance vision and increase electrosensory processes by distributing the pores over a large area.

Secondly, unlike many other sharks they tend to form schools during the day of up to several hundred individuals, and then go on to become solitary again during the nighttime. 

Lastly, one hammerhead shark species (Sphyrna tiburo) was responsible for the first observed example of asexual reproduction in sharks in 2007. You can read more about that here!

Absolutely incredible animals.

10 things more likely to kill you than sharks, part 3 -falling out of bed
450 people are killed annually in the US falling out of bed. At least in the ocean you float.

10 things more likely to kill you than sharks, part 3 -falling out of bed

450 people are killed annually in the US falling out of bed. At least in the ocean you float.

Not all sharks like deep, open waters. Some like to stay on the ocean floors too like the tasseled wobbegong and the wobbegong! Not too surprisingly, wobbegong is aboriginal in origin and means “shaggy beard”

Shark week goes on, so lets talk about some pre-historic sharks and a discovery channel favourite - Megalodon.

These sharks all lived a very long time ago - the megalodon (top and bottom) between 28 and 1.5 million years ago, stetacanthus (middle left) around 360 million years ago and finally helicoprion around 280 million years ago. 

Despite what certain documentaries might imply, megalodon is most definetly extinct, but at its time it was the apex predator of the ocean,  up to 25 meters in length, weighing in at 100 tonnes and with teeth up to 200 mm. It was probably found all over the world and fed on large whales.

Less is known about the other two sharks pictured, quite a few fossils of the distinctHelicoprion tooth whirl have been found but if it had any functionality beyond what our jaws have now is unclear. It’s thought that the odd anvil shaped dorsal of stetacanthus may have been used for scaring of predators or even attaching itself to larger animals. 

Freaky stuff, but most definitely all very extinct.

Shark fact: Great whites can jump 2.5m out of the water and reach over 20 mph doing so. Incredibly powerful animals.

Shark fact: Great whites can jump 2.5m out of the water and reach over 20 mph doing so. Incredibly powerful animals.

Shark eggs are by far the coolest eggs on earth. Most sharks actually give birth to live young, but a few, mostly smaller sharks lay these incredible eggs. From top to bottom, left to right we’ve got a Port Jackson Shark egg (being fed upon by a crested bullhead shark), Japanese swellshark, Crested bullhead shark and finally an Australian swellshark. 

The eggs mature for between 9-12 months depending on the species, and hatch tiny little shark babies. 

Most lay quite a few eggs as up 90% can be lost to tides, fishing and predation.